This research was supported by the German Federal Ministery for Education and Research (BMBF) funded &#8220;Virtual Liver Network&#8221;. I&#8217;d like to thank Frank Schubert and Rene Gumpert from the media center of Jena University Hospital for their help in producing the video and creating the animation and Isabel Jank for recording the audio.

Housing and all procedures carried out were in accordance with German Animal Welfare Legislation.
1. Sensors Calibration&#160;(Follow Manufacturer&#39;s Instructions for Sensors Calibration)
1.1) Millar catheter calibration. Pre-soak the tip of the catheter in sterile water or saline for 30 min prior to balance (zeroing) and calibration.
<ol>
	<li>Connect the millar sensor to the millar1 channel of bridge amplifier and insert the millar sensor tip into water column.</li>
	<li>Set the water column value to 0 cmH2O. In data analysis software window, choose bridge amplify and zero it. The baseline value 0 cmH2O can be set.</li>
	<li>Set the water column value to 20 cmH2O. Run data analysis software window progress, and stop. Choose &#8220;units&#8221; in the window of bridge amplify, set the baseline of 0 and 20 cmH2O accordingly. Adjust the &#8220;unit&#8221; to cmH2O.</li>
	<li>Calibrate the millar2 for measuring CAP in the same way (set two base line 90 and 110 cmH2O).</li>
</ol>
1.2) Blood flow probe calibration
<ol>
	<li>Put the probe into deionized water. Connect the probe with transonic flow probe system.</li>
	<li>In data analysis software window, choose Input amplify to zero the flow probe. Adjust the units.</li>
	<li>Press the button to &#8220;test channel&#8221; to collect the signal: if the signal has 3-4 bars, it means the signal is good. In case a good signal is acquired, the procedure can be continued.</li>
	<li>Press the button to &#8220;zero channel&#8221; and scale channel to see whether the value has been calibrated or not.</li>
	<li>Press the button to &#8220;measure channel&#8221; for later measuring.</li>
</ol>
2. Prepare the Mouse for the Surgical Procedure
<ol>
	<li>Place the mouse in an induction chamber and anesthetize the mouse with 2% isoflurane and 0.3 ml/min oxygen. The operation can be performed if the toe-pinch withdrawal&#160;reflex of the mouse is absent.</li>
	<li>Shave the fur of surgical regions, which include the left neck and abdomen.</li>
	<li>Place the mouse on the operation table and fix it using tapes. Use vet ointment on eyes to prevent dryness during the operation period.</li>
	<li>Place a gauze cushion under the neck for optimal exposure of the operation field of neck.</li>
	<li>Disinfect the operation field and place sterilized gauzes to cover the mouse only leaving the surgical field open.</li>
</ol>
3. Vital Parameters Measurement
<ol>
	<li>Insert the ECG needles subcutaneously into the paws of mouse.</li>
	<li>Place the respiratory sensor under the back of the mouse.</li>
	<li>Place the temperature probe into the rectum of the mouse.</li>
	<li>Record temperature, ECG and respiratory rate of the mouse in data analysis software.</li>
</ol>
4. Neck Operation for Systemic Cardiovascular Monitoring
4.1) Vessel dissection
<ol>
	<li>Identify the middle line of the neck, middle point of clavicle, the angle of mandible.</li>
	<li>Make a 2cm longitudinal incision from the angle of mandible to the middle point of clavicle which is 0.5cm to the left side of the middle line.</li>
	<li>Dissect the submandibular gland, turn it over and cover it with saline soaked gauze.</li>
	<li>Identify the jugular vein, dissect it and place three 6-0 silk sutures under the vein for later ligation and fixation.</li>
	<li>Identify the sternocleidomastoid muscle, separate it from the superior belly of omohyoid and posterior belly of digastric muscle, and pull it with a retractor for easy exposure of the carotid artery.</li>
	<li>Dissect the carotid artery and place three 6-0 silk sutures under the artery for later ligation and fixation.</li>
</ol>
4.2) Carotid artery blood flow measurement
<ol>
	<li>Place the transonic probe around the carotid artery, keep it stable, and optimize the contact using ultrasound gel or saline.</li>
	<li>Record blood flow velocity of the carotid artery as indicated on the small screen of the transonic device using data analysis software</li>
	<li>Remove the probe after completing the measurement</li>
</ol>
4.3) Carotid artery pressure measurement (CAP)
<ol>
	<li>Ligate the distal end of the carotid artery and clamp its proximal end.</li>
	<li>Place 2 fixing sutures around the carotid artery. Use 10-0 prolene for the stay suture.</li>
	<li>Make a small incision on the anterior wall of the vessel.</li>
	<li>Insert the millar catheter and fix it with pre-placed sutures.</li>
	<li>Record the CAP in data analysis software.</li>
</ol>
4.4) Jugular vein blood flow measurement
<ol>
	<li>Lift the jugular vein and place the transonic flow probe to measure the flow rate.</li>
	<li>Record the flow rate in data analysis software.</li>
</ol>
4.5) Central venous pressure measurement (CVP)
<ol>
	<li>Clamp the proximal end of the jugular vein and ligate the distal end.</li>
	<li>Cut a small incision using microscissors on the anterior wall of the vessel.</li>
	<li>Insert the fluid-filled catheter and fix it with the pre-placed suture lines.</li>
	<li>Record the CVP in data analysis software.</li>
</ol>
5. Abdominal Operation for Acquisition of Hepatic Hemodynamics
5.1) Vessel identification
<ol>
	<li>Make a transverse incision on the abdomen.</li>
	<li>Eventerate the intestines to the left side and cover with wet gauze.</li>
	<li>Identify the inferior vena cava, the portal vein, the common hepatic artery and the proper hepatic artery.</li>
	<li>Drop some warm saline in the abdomen and on the surface of the intestines every 5 min during the whole monitoring procedure.</li>
</ol>
5.2) Measurement of portal blood flow
<ol>
	<li>Dissect the portal vein.</li>
	<li>Place 6-0 silk under the portal vein to facilitate lifting of the vessel when placing the flow probe.</li>
	<li>Place the transonic flow probe around the portal vein and measure its blood flow rate.</li>
	<li>Record the blood flow rate of the portal vein.</li>
</ol>
5.3) Measurement of Common hepatic artery flow
<ol>
	<li>Dissect the common hepatic artery cautiously.</li>
	<li>Place one 6-0 silk suture around the vessel to facilitate lifting of the vessel.</li>
	<li>Place the flow probe around the artery.</li>
	<li>Measure its blood flow and acquire the data.</li>
</ol>
5.4) Measurement of portal vein pressure (PVP)
<ol>
	<li>Choose one branch of the mesenteric vein with few side branches, which drains straight into the portal vein.</li>
	<li>Ligate the distal end of the selected mesenteric vein. Make sure that ligation is close to the intestinal tube. Ligate its small branches</li>
	<li>Place 2 fixing sutures using 6-0 prolene around the vein. The key point of this procedure is to avoid touching the mesenteric artery when ligating the vein.</li>
	<li>Clamp the proximal end of the portal vein.</li>
	<li>Place 2 stay sutures using 10-0 prolene. Some bleeding will occur since the stay suture should penetrate the vascular wall of the fine mesenteric vein.</li>
	<li>Make a small incision on the vein using a microscissor obliquely at a 45 degrees angle.</li>
	<li>Insert the Millar catheter through the mesenteric vein into the portal vein and fix it</li>
	<li>Record the portal vein pressure. At the end of the procedure, sacrifice the mice by exsanguination under anesthesia.</li>
</ol>

<ol>
	<li>Albuszies, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+increased+cardiac+output+on+hepatic+and+intestinal+microcirculatory+blood+flow,+oxygenation,+and+metabolism+in+hyperdynamic+murine+septic+shock.">Effect of increased cardiac output on hepatic and intestinal microcirculatory blood flow, oxygenation, and metabolism in hyperdynamic murine septic shock.</a> Crit Care Med. 33 (10), 2332-2338 (2005).</li><li>Bernhard, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phosphatidylcholine+molecular+species+in+lung+surfactant:+composition+in+relation+to+respiratory+rate+and+lung+development.">Phosphatidylcholine molecular species in lung surfactant: composition in relation to respiratory rate and lung development.</a> Am. J. Respir. Cell Mol. Biol. 25 (6), 725-731 (2001).</li><li>Cheever, A. W., Warren, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Portal+vein+ligation+in+mice:+portal+hypertension,+collateral+circulation,+and+blood+flow.">Portal vein ligation in mice: portal hypertension, collateral circulation, and blood flow.</a> 18, 405-407 (1963).</li><li>Costa, G., Aguiar, B. G., Coelho, P. M., Cunha-Melo, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+increase+of+portal+pressure+during+the+acute+and+chronic+phases+of+murine+schistosomiasis+mansoni+and+its+reversibility+after+treatment+with+oxamniquine.">On the increase of portal pressure during the acute and chronic phases of murine schistosomiasis mansoni and its reversibility after treatment with oxamniquine.</a> Acta Trop. 89 (1), 13-16 (2003).</li><li>Cui, S., Shibamoto, T., Zhang, W., Takano, H., Kurata, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Venous+resistance+increases+during+rat+anaphylactic+shock.">Venous resistance increases during rat anaphylactic shock.</a> Shock. 29 (6), 733-739 (2008).</li><li>Geerts, A. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+three+research+models+of+portal+hypertension+in+mice:+macroscopic,+histological+and+portal+pressure+evaluation.">Comparison of three research models of portal hypertension in mice: macroscopic, histological and portal pressure evaluation.</a> Int. J. Exp. Pathol. 89 (4), 251-263 (2008).</li><li>Huang, H., Deng, M., Jin, H., Dirsch, O., Dahmen, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intraoperative+vital+and+haemodynamic+monitoring+using+an+integrated+multiple-channel+monitor+in+rats.">Intraoperative vital and haemodynamic monitoring using an integrated multiple-channel monitor in rats.</a> Lab Anim. 44 (3), 254-263 (2010).</li><li>Krege, J. H., Hodgin, J. B., Hagaman, J. R., Smithies, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+noninvasive+computerized+tail-cuff+system+for+measuring+blood+pressure+in+mice.">A noninvasive computerized tail-cuff system for measuring blood pressure in mice.</a> Hypertension. 25 (5), 1111-1115 (1995).</li><li>Kuga, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+and+local+autoregulation+of+cerebrovascular+blood+flow:+a+deep-brain+imaging+study+in+the+mouse.">Rapid and local autoregulation of cerebrovascular blood flow: a deep-brain imaging study in the mouse.</a> J. Physiol.. 587 (Pt 4), 745-752 (2009).</li><li>Muraki, T., Strain Kato, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=difference+in+the+effects+of+morphine+on+the+rectal+temperature+and+respiratory+rate+in+male+mice.">difference in the effects of morphine on the rectal temperature and respiratory rate in male mice.</a> Psychopharmacology (Berl). 89 (1), 60-64 (1986).</li><li>Nielsen, J. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Left+ventricular+volume+measurement+in+mice+by+conductance+catheter:+evaluation+and+optimization+of+calibration.">Left ventricular volume measurement in mice by conductance catheter: evaluation and optimization of calibration.</a> Am. J. Physiol Heart Circ. Physiol. 293 (1), H534-H540 (2007).</li><li>Sakamoto, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improvement+of+portal+hypertension+and+hepatic+blood+flow+in+cirrhotic+rats+by+oestrogen.">Improvement of portal hypertension and hepatic blood flow in cirrhotic rats by oestrogen.</a> Eur. J. Clin. Invest. 35 (3), 220-225 (2005).</li><li>Reverter, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+deep+sedation+on+the+accuracy+of+hepatic+and+portal+venous+pressure+measurements+in+patients+with+cirrhosis.">Impact of deep sedation on the accuracy of hepatic and portal venous pressure measurements in patients with cirrhosis.</a> Liver Int. 34 (1), 16-25 (2014).</li></ol>

The authors declare that they have no competing financial interests.

Monitoring of hepatic hemodynamics is an important research tool in hepatology and hepatobiliary surgery. Acquisition of hepatic hemodynamic data helps to characterize the effect of hepatobiliary procedures on the circulatory system. Acquisition of hepatic hemodynamic data is also needed to study the effect of drugs affecting portal pressure and portal flow, e.g., as needed in studies evaluating vasoactive drugs.
Despite the small size, the vital parameters, systemic and hepatic hemodynamics can be monitored in mice. The critical steps within the protocol were as follows: First, it is important to place the animal on a warming pad during the whole procedure to avoid hypothermia which may lead to circulatory dysfunction. Second, it is crucial to be very cautious when dissecting the vessels of a mouse, since the vessel wall of mouse is very fragile and thin. It seems best to fix the vessel wall by grabbing some fat tissue on the surface instead of grabbing the vessel wall itself. Third, it is vital to avoid accidental ligation of mesenteric artery for not impairing the arterial supply when placing the fixing sutures around the mesenteric vein.
However, the invasive mentoring technique has some limitations. The first one is its invasiveness by itself. This monitoring technique is an invasive method, which requires a surgical intervention. Therefore the monitoring procedure itself may cause side effects for the animals. Hence, we only used this procedure to acquire hemodynamic parameters in normal animals and in acute experiments, but not in survival experiments. In a next step, we want to evaluate this technique in survival experiments. The second limitation of this procedure is that it requires substantial microsurgical experience. Hemodynamic monitoring in mice should only be performed by specifically trained microsurgeons. The most difficult part of this monitoring procedure is the insertion of the Millar catheter in the small mesenteric vein, since this vein is extremely fragile. In our hands, about 10 training operations were needed for an experienced microsurgeon prior to technically mastering this procedure. Experience was defined of having successfully performed more than 50 vascular anastomosis (carotid artery, jugular vein) in rats or mice. The third limitation is that the portal pressure obtained with this method may be below the physiological range for a normal animal. Mesenteric vein ligation and catheter insertion may reduce the total volume of blood draining into the portal vein by an estimated 10%. However, this physiological range cannot be acquired using the currently available devices. Similarly, the effect of anesthesia itself on PVP cannot be excluded13. However, since all animals are subjected to the same intervention, the potential error would be a systematic error. Therefore, data interpretation should be done with caution focusing on relative changes within an animal and not necessarily on absolute differences between animals.
However, there are little alternatives to the invasive hemodynamic monitoring in rodents. Non-invasive monitoring is limited to the acquisition of the systemic blood pressure. Portal pressure or portal flow cannot be determined non-invasively in mice. Telemetric monitoring is also limited to the acquisition of the systemic blood pressure. No reports were found regarding the telemetric acquisition of other hemodynamic parameters.
This full intraoperative monitoring procedure is needed to understand hepatic physiological processes such as regulation of liver perfusion, liver regeneration and hepatobiliary surgery comprehensively. The ability to monitor and collect data of laboratory animals intraoperatively in real-time thus represents a significant advance in the study of liver disease and portal hypertension.

The overall goal of this video was to demonstrate a real-time monitoring procedure for acquiring systemic and hepatic hemodynamic parameters. The rationale for developing this procedure is its great value for experimental interventions in mice&#160;that require&#160;obtaining systemic and hepatic hemodynamic parameters. The procedure can be applied to na&#239;ve animals and during or after a given hepato-biliary experimental surgical intervention, such as partial hepatectomy, portal vein ligation and liver transplantation.
Acquisition of hepatic hemodynamic data in rodents requires the proposed invasive procedure. Hepatic perfusion cannot be obtained non-invasively. However, there are alternatives for the acquisition of the systemic blood pressure. Monitoring techniques such as the tail cuff technique8 have been utilized for acquiring the blood pressure in both rats and mice. The tail cuff technique can be applied in conscious animals. When measuring the blood pressure, the animal needs to be placed and fixed in a specific uncomfortable position. In the manual of the tail-cuff device, the manufacturer states that mice may become nervous and stressed which may diminish the circulation in the tail. Under that circumstance, the peripheral blood pressure acquired in the tail may be much lower than the central blood pressure.
The full monitoring procedure was performed with an integrated multiple-channel monitor using a series of sensors for data acquisition. The blood pressure was obtained by inserting a catheter into the respective vessel after careful microsurgical dissection and exposure under the microscope. The flow rate was measured by placing a transonic flow probe around each vessel.
We already reported a similar intraoperative monitoring procedure for rats resulting in a comprehensive series of physiological hemodynamic data comparable to single data reported from other groups7. Therefore we considered this procedure to represent a good basis for adapting it to the mouse, a species 10-fold smaller than the rat. The key difference to the rat procedure is the use of Millar catheters for acquiring blood pressure data instead of a fluid-based catheter system. Flow data were also acquired with transonic flow probes, just much smaller ones than for the corresponding rat vessels.
Due to the small size of the animal, instrumentation of mice is technically challenging, but feasible. Once instrumentation is completed, data acquisition and primary life data analysis is simple, since a predefined setting file can be used. The setting file has to be defined once at the beginning of a series of experiments and can be stored and used for all subsequent experiments.
Up to now we applied this procedure to assess hepatic hemodynamic effects in acute experiments. We measured CAP and PVP before and immediately after 70% partial hepatectomy (PH) and in clamping/de-clamping experiments. We clamped the hepato-duodenal ligament of the right lobe representing 20% of the liver mass followed by brief (5min) clamping of the median and left lateral lobe representing totally 90% of the liver mass. De-clamping started with releasing the clamp from the right lobe followed by freeing the median and left lateral lobe. Maximal clamping time was below 10 min.

<table><tbody><tr><td>PowerLab 16/30&amp;nbsp;</td><td>ADInstruments</td><td>PL3516</td><td></td></tr><tr><td>Quad Bridge Amp</td><td>ADInstruments</td><td>FE224</td><td>Bridge amplifier&amp;nbsp;</td></tr><tr><td>Animal Bio Amp</td><td>ADInstruments</td><td>FE136</td><td></td></tr><tr><td>Needle Electrodes for FE136 (3 pk)</td><td>ADInstruments</td><td>MLA1213</td><td></td></tr><tr><td>Perivascular Flowmeter Module</td><td>Transonic</td><td>TS420</td><td></td></tr><tr><td>Flowprobe MA0.5PSB/MA1PSB</td><td>Transonic</td><td>MA0.5PSB/MA1PSB</td><td></td></tr><tr><td>SPR-1000 Mouse Pressure Catheter</td><td>Millar instruments</td><td>841-0001</td><td></td></tr><tr><td>fluid filled catheter&amp;nbsp;</td><td>Terumo</td><td>SR+DU2619PX</td><td>26G, 0.64&amp;times;19mm</td></tr><tr><td>micro scissors</td><td>F&amp;middot;S&amp;middot;L</td><td>No. 14058-09</td><td></td></tr><tr><td>micro serrefine</td><td>F&amp;middot;S&amp;middot;L</td><td>No.18055-05</td><td></td></tr><tr><td>Micro clamps applicator</td><td>F&amp;middot;S&amp;middot;L</td><td>No. 18057-14</td><td></td></tr><tr><td>Straight micro forceps</td><td>F&amp;middot;S&amp;middot;L</td><td>No. 00632-11</td><td></td></tr><tr><td>Curved micro forceps</td><td>F&amp;middot;S&amp;middot;L</td><td>No. 00649-11</td><td></td></tr><tr><td>needle-holder</td><td>F&amp;middot;S&amp;middot;L</td><td>No. 12061-01</td><td></td></tr><tr><td>6-0 silk</td><td>ethicon</td><td></td><td></td></tr><tr><td>6-0 prolene</td><td>ethicon</td><td></td><td></td></tr><tr><td>7-0 prolene</td><td>ethicon</td><td></td><td></td></tr><tr><td>10-0 prolene</td><td>ethicon</td><td></td><td></td></tr><tr><td>Tail cut-off device&amp;nbsp;</td><td>Kent Scientific</td><td></td><td>www.kentscientific.com</td></tr><tr><td>LabChart7</td><td>ADInstruments</td><td></td><td>data&amp;nbsp; analysis software&amp;nbsp;</td></tr></tbody></table>

monitoring of systemic and hepatic hemodynamic parameters in mice

The use of mouse models in experimental research is of enormous importance for the study of hepatic physiology and pathophysiological disturbances. However, due to the small size of the mouse, technical details of the intraoperative monitoring procedure suitable for the mouse were rarely described. Previously we have reported a monitoring procedure to obtain hemodynamic parameters for rats. Now, we adapted the procedure to acquire systemic and hepatic hemodynamic parameters in mice, a species ten-fold smaller than rats. This film demonstrates the instrumentation of the animals as well as the data acquisition process needed to assess systemic and hepatic hemodynamics in mice. Vital parameters, including body temperature, respiratory&#160;rate&#160;and heart&#160;rate were recorded throughout the whole procedure. Systemic hemodynamic parameters consist of carotid artery pressure (CAP) and central venous pressure (CVP). Hepatic perfusion parameters include portal vein pressure (PVP), portal flow rate as well as the flow rate of the common hepatic artery (table 1). Instrumentation and data acquisition to record the normal values was completed within 1.5 h. Systemic and hepatic hemodynamic parameters remained within normal ranges during this procedure.
This procedure is challenging but feasible. We have already applied this procedure to assess hepatic hemodynamics in normal mice as well as during 70% partial hepatectomy and in liver lobe clamping experiments. Mean PVP after resection (n= 20), was 11.41&#177;2.94 cmH2O which was significantly higher (P&#60;0.05) than before resection (6.87&#177;2.39 cmH2O). The results of liver lobe clamping experiment indicated that this monitoring procedure is sensitive and suitable for detecting small changes in portal pressure and portal flow rate. In conclusion, this procedure is reliable in the hands of an experienced micro-surgeon but should be limited to experiments where mice are absolutely needed.

Vital parameters of the mice such as respiratory rate and heart rate are obviously much higher than in rat. Mean systemic blood pressure and jugular vein pressure are similar to rat values and even similar to the human data.
Hepatic hemodynamic data are obviously different. We obtained normal values from 8 mice. Portal blood flow in normal mice ranged between 1.6 to 2.3 ml/min. Flow in the common hepatic artery ranged from 0.10 to 0.35 ml/min. Portal vein pressure in normal animals was in the wide range from 4.4 to 11.2 cmH2O with a mean value of 8.09 &#177; 2.47 cmH2O (Table 1). This wide range may lead to small but not significant differences when comparing the mean value of small groups of normal animals.
Since we observed considerable inter-individual differences especially in the portal pressure, we tested whether small intra-individual differences could be detected with this technique. We evaluated this procedure in two different experimental settings: partial hepatectomy and liver lobe clamping/de-clamping. Portal pressure before and immediately after 70% partial hepatectomy (n=20) in the same animal (Figure 1) increased by 2-fold from 6.87&#177;2.39 and 11.41&#177;2.94 cmH2O (P =&#60;0.001). These results were in a similar range as observed in other species 5,12 and also in humans 7.
Normal portal vein pressure and portal pressure before resection were acquired from two different groups (one from normal monitoring parameters group, the other from 70%PH group). Due to the wide range of portal pressure in normal mice (4 to 11 cmH2O), the mean values of small groups of animals may be slightly different, as observed in our experiment (8.09 &#177; 2.47 cmH2O versus 6.87&#177;2.39 cmH2O). However, when analyzing the data, we found that there was no statistically significant difference between these two groups (P = 0.237).
The clamping/de-clamping experiment was designed to demonstrate that the procedure is sensitive enough to pick up even smaller changes in the portal pressure. Clamping of the right lobe representing 20% of the liver mass resulted in an increase of about 17%. Further clamping of the median and left lateral lobe caused an increase of at least 2-3 folds compared to the starting portal pressure. Portal pressure returned gradually to the starting pressure, when releasing the clamp from the right lobe resulting in clamping of 70% of the liver. The pressure returned to the starting level when removing the clamp from the left portal vein supplying the median and left lateral lobe (Figure 2 and Table 2). The MAP of the sham operation group remained stable within 1h after opening the abdomen. The MAP of mice in the control group, obtained at the comparable time point as in the clamping experiment, had no significant difference compared with the MAP of the experimental group. The results of both experiments revealed that even small intra-individual changes of less than 20% could be detected with this procedure.
Typical complications like severe bleeding and congestion may occur during the procedure. Since severe blood loss would cause significant decrease of MAP as well as PVP, the results of mice with this complication should be eliminated. To avoid venous congestion and thrombosis when performing liver lobe clamping experiment, we suggest injecting a small dose heparin (500 U/kg) intra-operatively before clamping. Common hepatic artery can undergo a transient vessel spasm upon handling such as lifting the vessel and placing the probe. This might cause a transient brief ischemia of the liver. In general, the spasm may resolve spontaneously within minutes. A short vascular spasm in the CHA is not posing a serious problem to the life of the animal, but might interfere with experimental results, when focusing on hepatic ischemia reperfusion injury.
In conclusion, this procedure is challenging but feasible. It requires some training even for experienced micro-surgeons. Due to the high inter-individual variability comparison of pressure data obtained in different animals before and after an intervention may not lead to conclusive results. Therefore we recommend this procedure to study short term regulation of hepatic hemodynamics in acute experiments by acquiring the data before and after the intervention within the same animal.
<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr height="26">
			<td colspan="2">Parameters</td>
			<td>Own data obtained</td>
			<td>Parameters reported</td>
		</tr>
		<tr>
			<td rowspan="3">Vital parameters</td>
			<td>Heart rate (n=8)</td>
			<td>418&#177;55 BPM</td>
			<td>389(353-566) BPM 1</td>
		</tr>
		<tr>
			<td>respiratory rate (n=2)</td>
			<td>162&#177;11 BPM</td>
			<td>254 &#177; 28 BPM 2</td>
		</tr>
		<tr>
			<td>Temperature (n=8)</td>
			<td>33.56&#177;0.54&#176;C</td>
			<td>36.1&#8211;36.6&#176;C11</td>
		</tr>
		<tr>
			<td colspan="2">Systemic blood pressure (CAP) (n=8)</td>
			<td>130.54 &#177; 20.47 cmH2O 
			( =96.02 &#177;&#160;15.06 mmHg)</td>
			<td>94 &#177; 15 mmHg 9</td>
		</tr>
		<tr>
			<td colspan="2">Central venous pressure (CVP) (n=2)</td>
			<td>&#160; 8.90 &#177; 3.25 cmH2O</td>
			<td>5.9 &#177; 2.0 cmH2O 11</td>
		</tr>
		<tr>
			<td rowspan="6">Hepatic hemodynamics</td>
			<td rowspan="2">Portal vein flow (n=6)</td>
			<td rowspan="2">&#160; 2.03 &#177; 0.24 ml/min</td>
			<td>3.0 (2.5-3.1) ml/min 1</td>
		</tr>
		<tr>
			<td>3.3 ml/min 1</td>
		</tr>
		<tr>
			<td>Common hepatic artery flow (n=6)</td>
			<td>&#160; 0.20 &#177; 0.09 ml/min</td>
			<td>Not found</td>
		</tr>
		<tr>
			<td rowspan="3">PVP (n=8)</td>
			<td rowspan="3">8.09 &#177; 2.47 cmH2O (=5.95 &#177; 1.82mmHg)</td>
			<td>5.3&#177;1.4 cm saline 3</td>
		</tr>
		<tr>
			<td>8.7 &#177; 2.1 mmHg 4</td>
		</tr>
		<tr>
			<td>4mmHg 6</td>
		</tr>
	</tbody>
</table>
Table 1. Normal systemic and hepatic hemodynamic parameters of mice acquired using this monitoring procedure. CAP: carotid artery pressure; MAP: mean arterial pressure; CVP: central venous pressure; PVP: portal vein pressure.
<img alt="Figure 1" fo:content-width="5in" src="/files/ftp_upload/51955/51955fig1highres.jpg" width="500" /> 
Figure 1. PVP before and after 70%PH. Portal vein pressure before and after 70%partial hepatectomy (n=20) were 6.87&#177;2.39 and 11.41&#177;2.94 cmH2O. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/51955/51955fig1highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Parameters (cmH2O)</td>
			<td>After laparotomy</td>
			<td>After clamping 20% of liver (RL)</td>
			<td>After clamping 90% of liver (RL+ML+LLL)</td>
			<td>After clamping 70% of liver (ML+LLL)</td>
			<td>At the end (release all clamps)</td>
		</tr>
		<tr>
			<td>PVP - Clamping exp group (n=10)</td>
			<td>9.59&#177;4.00</td>
			<td>10.45&#177;3.89</td>
			<td>25.78&#177;8.99</td>
			<td>16.91&#177;9.86</td>
			<td>11.14&#177;4.48</td>
		</tr>
		<tr>
			<td>Mean CAP - Clamping exp group (n=10)</td>
			<td>121.50&#177;18.67</td>
			<td>95.89&#177;32.76</td>
			<td>74.41&#177;35.35</td>
			<td>93.88&#177;42.96</td>
			<td>89.44&#177;44.20</td>
		</tr>
		<tr>
			<td>Mean CAP - Sham group (n=3)</td>
			<td>123.33&#177;12.42</td>
			<td>121.0&#177;5.57</td>
			<td>124.00&#177;8.66</td>
			<td>127.33&#177;7.23</td>
			<td>123.00&#177;8.89</td>
		</tr>
	</tbody>
</table>

Table 2. Hemodynamic response after clamping and declamping of different liver lobes (n=10). RL: right lobe, ML: median lobe (including right median lobe and left median lobe), LLL: left lateral lobe.

<img alt="Figure 2" fo:content-width="7.18in" src="/files/ftp_upload/51955/51955fig2highres.jpg" width="675" /> 
Figure 2. Hemodynamic response after clamping and declamping of different liver lobes (animal ID: CHI-108). A. PVP right after inserting the millar catheter was 8.8 cmH2O. PVP after clamping 20% liver lobe was 10.8 cmH2O. B.PVP rose to 17.5 cmH2O after clamping 90% liver lobe. C. PVP decreased to 10.3 cmH2O when releasing the clamp of the right lobe. D.PVP went back to 8.7 cmH2O as in the beginning after releasing all the clamps. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/51955/51955fig2highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Monitoring of Systemic and Hepatic Hemodynamic Parameters in Mice at JoVE.com

Monitoring of Systemic and Hepatic Hemodynamic Parameters in Mice

This film demonstrates how to acquire systemic and hepatic hemodynamics in mice. The whole monitoring includes acquisition of vital parameters, systemic blood pressure, central venous pressure, common hepatic artery flow rate, and portal vein pressure as well as the portal flow rate in mice.

The use of mouse models in experimental research is of enormous importance for the study of hepatic physiology and pathophysiological disturbances. ...

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Universidad San Sebastian

Research

JoVE Journal

Medicine

16.0K Views.  Jena University Hospital. This film demonstrates how to acquire systemic and hepatic hemodynamics in mice. The whole monitoring includes acquisition of vital parameters, systemic blood pressure, central venous pressure, common hepatic artery flow rate, and portal vein pressure as well as the portal flow rate in mice.

Video: Monitoring of Systemic and Hepatic Hemodynamic Parameters in Mice

Transthoracic Echocardiography in Mice

In recent years, murine models have become the primary avenue for studying the molecular mechanisms of cardiac dysfunction resulting from changes in gene expression. Transgenic and gene targeting methods can be used to generate mice with altered cardiac size and function,1-3 and as a result, in vivo techniques are needed to evaluate their cardiac phenotype. Transthoracic echocardiography, pulse wave Doppler (PWD), and tissue Doppler imaging (TDI) can be used to provide dimensional measurements of the mouse heart and to quantify the degree of cardiac systolic and diastolic performance. Two-dimensional imaging is used to detect abnormal anatomy or movements of the left ventricle, whereas M-mode echo is used for quantification of cardiac dimensions and contractility.4,5 In addition, PWD is used to quantify localized velocity of turbulent flow,6 whereas TDI is used to measure the velocity of myocardial motion.7 Thus, transthoracic echocardiography offers a comprehensive method for the noninvasive evaluation of cardiac function in mice.

Transthoracic echocardiography offers a noninvasive method for the evaluation of cardiac function in mice. A combination of ultrasound and Doppler imaging modalities can be used to obtain dimensional measurements of the heart and intracardiac blood flow, which together provide an assessment of cardiac systolic and diastolic performance.

In recent years, murine models have become the primary avenue for studying the molecular mechanisms of cardiac dysfunction resulting from changes in gene ...

Long Term Intravital Multiphoton Microscopy Imaging of Immune Cells in Healthy and Diseased Liver Using CXCR6.Gfp Reporter Mice

Liver inflammation as a response to injury is a highly dynamic process involving the infiltration of distinct subtypes of leukocytes including monocytes, neutrophils, T cell subsets, B cells, natural killer (NK) and NKT cells. Intravital microscopy of the liver for monitoring immune cell migration is particularly challenging due to the high requirements regarding sample preparation and fixation, optical resolution and long-term animal survival. Yet, the dynamics of inflammatory processes as well as cellular interaction studies could provide critical information to better understand the initiation, progression and regression of inflammatory liver disease. Therefore, a highly sensitive and reliable method was established to study migration and cell-cell-interactions of different immune cells in mouse liver over long periods (about 6 hr) by intravital two-photon laser scanning microscopy (TPLSM) in combination with intensive care monitoring.
The method provided includes a gentle preparation and stable fixation of the liver with minimal perturbation of the organ; long term intravital imaging using multicolor multiphoton microscopy with virtually no photobleaching or phototoxic effects over a time period of up to 6 hr, allowing tracking of specific leukocyte subsets; and stable imaging conditions due to extensive monitoring of mouse vital parameters and stabilization of circulation, temperature and gas exchange.
To investigate lymphocyte migration upon liver inflammation CXCR6.gfp knock-in mice were subjected to intravital liver imaging under baseline conditions and after acute and chronic liver damage induced by intraperitoneal injection(s) of carbon tetrachloride (CCl4).
CXCR6 is a chemokine receptor expressed on lymphocytes, mainly on Natural Killer T (NKT)-, Natural Killer (NK)- and subsets of T lymphocytes such as CD4 T cells but also mucosal associated invariant (MAIT) T cells1. Following the migratory pattern and positioning of CXCR6.gfp+ immune cells allowed a detailed insight into their altered behavior upon liver injury and therefore their potential involvement in disease progression.

Stable intravital high-resolution imaging of immune cells in the liver is challenging. Here we provide a highly sensitive and reliable method to study migration and cell-cell-interactions of immune cells in mouse liver over long periods (about 6 hours) by intravital multiphoton laser scanning microscopy in combination with intensive care monitoring.

Liver inflammation as a response to injury is a highly dynamic process involving the infiltration of distinct subtypes of leukocytes including monocytes, ...

Immunology and Infection

Long-term Blood Pressure Measurement in Freely Moving Mice Using Telemetry

During the development of new vasoactive agents, arterial blood pressure monitoring is crucial for evaluating the efficacy of the new proposed drugs. Indeed, research focusing on the discovery of new potential therapeutic targets using genetically altered mice requires a reliable, long-term assessment of the systemic arterial pressure variation. Currently, the gold standard for obtaining long-term measurements of blood pressure in ambulatory mice uses implantable radio-transmitters, which require&#160;artery cannulation. This technique eliminates the need for tethering, restraining, or anesthetizing the animals which introduce stress and artifacts during data sampling. However, arterial blood pressure monitoring in mice via catheterization can be rather challenging due to the small size of the arteries. Here we present a step-by-step guide to illustrate the crucial key passages for a successful subcutaneous implantation of radio-transmitters and carotid artery cannulation in mice. We also include examples of long-term blood pressure activity taken from freely moving mice after a period of post-surgery recovery. Following this procedure will allow reliable direct blood pressure recordings from multiple animals simultaneously.

The goal of this protocol is to assess systemic blood pressure in conscious freely moving mice using implantable radio-telemetry devices.

During the development of new vasoactive agents, arterial blood pressure monitoring is crucial for evaluating the efficacy of the new proposed drugs. ...

Novel Approach for Simultaneous Recording of Renal Sympathetic Nerve Activity and Blood Pressure with Intravenous Infusion in Conscious, Unrestrained Mice.

Renal sympathetic nerves contribute significantly to both physiological and pathophysiological phenomena. Evaluating renal sympathetic nerve activity (RSNA) is of great interest in many areas of research such as chronic kidney disease, hypertension, heart failure, diabetes and obesity. Unequivocal assessment of the role of the sympathetic nervous system is thus imperative for proper interpretation of experimental results and understanding of disease processes. RSNA has been traditionally measured in anesthetized rodents, including mice. However, mice usually exhibit very low systemic blood pressure and hemodynamic instability for several hours during anesthesia and surgery. Meaningful interpretation of RSNA is confounded by this non-physiological state, given the intimate relationship between sympathetic nervous tone and cardiovascular status. To address this limitation of traditional approaches, we developed a new method for measuring RSNA in conscious, freely-moving mice. Mice were chronically instrumented with radio-telemeters for continuous monitoring of blood pressure as well as a jugular venous infusion catheter and custom-designed bipolar electrode for direct recording of RSNA. Following a 48-72 hour recovery period, survival rate was 100% and all mice behaved normally. At this time-point, RSNA was successfully recorded in 80% of mice, with viable signals acquired up to 4 and 5 days post-surgery in 70% and 50% of mice, respectively. Physiological blood pressures were recorded in all mice (116&plusmn;2 mmHg; n=10). Recorded RSNA increased with eating and grooming, as well-established in the literature. Furthermore, RSNA was validated by ganglionic blockade and modulation of blood pressure with pharmacological agents. Herein, an effective and manageable method for clear recording of RSNA in conscious, freely-moving mice is described.

Anesthetized mice exhibit non-physiological systemic blood pressure, which precludes meaningful assessment of autonomic tone given the intimate relationship between blood pressure and the autonomic nervous system. Thus, a novel method to simultaneously record renal sympathetic nerve activity and blood pressure with intravenous infusion in conscious mice is outlined.

Renal sympathetic nerves contribute significantly to both physiological and pathophysiological phenomena. Evaluating renal sympathetic nerve activity ...

Uncontrolled Hemorrhagic Shock Modeled via Liver Laceration in Mice with Real Time Hemodynamic Monitoring

Uncontrolled hemorrhage is an important cause of preventable deaths among trauma patients. We have developed a murine model of uncontrolled hemorrhage via a liver laceration that results in consistent blood loss, hemodynamic alterations, and survival.
Mice undergo a standardized resection of the left-middle lobe of the liver. They are allowed to bleed without mechanical intervention. Hemostatic agents can be administered as pre-treatment or rescue therapy depending on the interest of the investigator. During the time of hemorrhage, real-time hemodynamic monitoring via a left femoral arterial line is performed. Mice are then sacrificed, blood loss is quantified, blood is collected for further analysis, and organs are harvested for analysis of injury. Experimental design is described to allow for simultaneous testing of multiple animals.
Liver hemorrhage as a model of uncontrolled hemorrhage exists in the literature, primarily in rat and porcine models. Some of these models utilize hemodynamic monitoring or quantify blood loss but lack consistency. The present model incorporates quantification of blood loss, real-time hemodynamic monitoring in a murine model that offers the advantage of using transgenic lines and a high-throughput mechanism to further investigate the pathophysiologic mechanisms in uncontrolled hemorrhage.

Uncontrolled hemorrhage, an important cause of mortality among trauma patients, can be modeled using a standard liver laceration in a murine model. This model results in consistent blood loss, survival, and allows for testing hemostatic agents. This article provides the step-by-step process to perform this valuable model.

Uncontrolled hemorrhage is an important cause of preventable deaths among trauma patients. We have developed a murine model of uncontrolled hemorrhage via ...

Invasive Hemodynamic Characterization of the Portal-hypertensive Syndrome in Cirrhotic Rats

This is a detailed protocol describing invasive hemodynamic measurements in cirrhotic rats for the characterization of portal hypertensive syndrome. Portal hypertension (PHT) due to cirrhosis is responsible for the most severe complications in patients with liver disease. The full picture of the portal hypertensive syndrome is characterized by increased portal pressure (PP) due to the increased intrahepatic vascular resistance (IHVR), hyperdynamic circulation, and increased splanchnic blood flow. Progressive splanchnic arterial vasodilation and increased cardiac output with elevated heart rate (HR) but low arterial pressure characterizes the portal hypertensive syndrome.
Novel therapies are currently being developed that aim to decrease PP by either targeting IHVR or increased splanchnic blood flow &#8212; but side effects on systemic hemodynamics may occur. Thus, a detailed characterization of portal venous, splanchnic, and systemic hemodynamic parameters, including measurement of PP, portal venous blood flow (PVBF), mesenteric arterial blood flow, mean arterial pressure (MAP), and HR is needed for preclinical evaluation of the efficacy of novel treatments for PHT. Our video article provides the reader with a structured protocol for performing invasive hemodynamic measurements in cirrhotic rats. In particular, we describe the catheterization of the femoral artery and the portal vein via an ileocolic vein and the measurement of portal venous and splanchnic blood flow via perivascular Doppler-ultrasound flow probes. Representative results of different rat models of PHT are shown.

Here we describe a detailed protocol for invasive measurements of hemodynamic parameters including portal pressure, splanchnic blood flow, and systemic hemodynamics in order to characterize the portal hypertensive syndrome in rats.

This is a detailed protocol describing invasive hemodynamic measurements in cirrhotic rats for the characterization of portal hypertensive syndrome. ...

Echocardiographic Measurement of Right Ventricular Diastolic Parameters in Mouse

Diastolic dysfunction is a prominent feature of right ventricular (RV) remodeling associated with conditions of pressure overload. However, the RV diastolic function is rarely quantified in experimental studies. This might be due to technical difficulties in the visualization of the RV in the apical four-chamber view in rodents. Here we describe two positions facilitating the visualization of the apical four-chamber view in mice to assess the RV diastolic function.
The apical four-chamber view is enabled by tilting the mouse fixation platform to the left and caudally (LeCa) or to the right and cranially (RiCr). Both positions provide images of comparable quality. The results of the RV diastolic function obtained from two positions are not significantly different. Both positions are comparably easy to perform. This protocol can be incorporated into published protocols and enables detailed investigations of the RV function.

Here we describe and compare two positions for obtaining the apical four-chamber view in mice. These positions enable the quantification of the right ventricular function, provide comparable results, and can be used interchangeably.

Diastolic dysfunction is a prominent feature of right ventricular (RV) remodeling associated with conditions of pressure overload. However, the RV ...

Invasive Hemodynamic Assessment for the Right Ventricular System and Hypoxia-Induced Pulmonary Arterial Hypertension in Mice

Pulmonary arterial hypertension (PAH) is a chronic and severe cardiopulmonary disorder. Mice are a popular animal model used to mimic this disease. However, the evaluation of right ventricular pressure (RVP) and pulmonary artery pressure (PAP) remains technically challenging in mice. RVP and PAP are more difficult to measure than left ventricular pressure because of the anatomical differences between the left and right heart systems. In this paper, we describe a stable right heart hemodynamic measurement method and its validation using healthy and PAH mice. This method is based on open-chest surgery and mechanical ventilation support. It is a complicated procedure compared to closed chest procedures. While a well-trained surgeon is required for this surgery, the advantage of this procedure is that it can generate both RVP and PAP parameters at the same time, so it is a preferable procedure for the evaluation of PAH models.

Here, we present a protocol to perform an invasive hemodynamic assessment of the right ventricle and pulmonary artery in mice using an open-chest surgery approach.

Pulmonary arterial hypertension (PAH) is a chronic and severe cardiopulmonary disorder. Mice are a popular animal model used to mimic this disease. ...

DREADDs Technology and Automated Blood Sampling

Remote Neuronal Activation Coupled with Automated Blood Sampling to Induce and Measure Circulating Luteinizing Hormone in Mice

Circulating luteinizing hormone (LH) levels are an essential index of the functioning of the hypothalamic-pituitary control of reproduction. The role of numerous inputs and neuronal populations in the modulation of LH release is still unknown. Measuring changes in LH levels in mice is often a challenge since they are easily disrupted by environmental stress. Current techniques to measure LH release and pulsatility require long-term training for mice to adapt to manipulation stress, certain restraint, the presence of the investigator, and working on individual animals, reducing its usefulness for many research questions.
This paper presents a technique to remotely activate specific neuronal populations using Designer Receptor Exclusively Activated by Designer Drugs (DREADDs) technology coupled with automated sequential blood sampling in conscious, freely moving, and undisturbed mice. We first describe the stereotaxic surgery protocol to deliver adeno-associated virus (AAV) vectors expressing DREADDs to specific neuronal populations. Next, we describe the protocol for carotid artery and jugular vein cannulation and postsurgical connection to the CULEX automated blood sampling system. Finally, we describe the protocol for clozapine-N-oxide intravenous injection for remote neuronal activation and automated blood collection. This technique allows for programmed automated sampling every 5 min or longer for a given period, coupled with intravenous substance injection at a desired time point or duration. Overall, we found this technique to be a powerful approach for research on neuroendocrine control.

Author Spotlight: Automated Infusion and Blood Sampling for Precise Hormonal Analysis in Conscious Mice

Luteinizing hormone (LH) pulsatility is a hallmark of reproductive function. We describe a protocol for remote activation of specific neuronal populations linked to serial automated blood collection. This technique allows timed hormonal modulation, multiplexing, and minimizing manipulation effects on LH levels in conscious freely moving, and undisturbed animals.

Circulating luteinizing hormone (LH) levels are an essential index of the functioning of the hypothalamic-pituitary control of reproduction. The role of ...

Neuroscience

Multiple Intravenous Bolus Dosing and Invasive Hemodynamic Assessment in a Hypoxia-Induced Mouse Pulmonary Artery Hypertension Model

Pulmonary arterial hypertension (PAH) is a progressive life-threatening disease, primarily affecting small pulmonary arterioles of the lung. Currently, there is no cure for PAH. It is important to discover new compounds that can be used to treat PAH. The mouse hypoxia-induced PAH model is a widely used model for PAH research. This model recapitulates human clinical manifestations of PAH Group 3 disease and is an important research tool to evaluate the effectiveness of new experimental therapies for PAH. Research using this model often requires the administration of compounds in mice. For a compound that needs to be given directly into the bloodstream, optimizing intravenous (IV) administration is a key part of the experimental procedures. Ideally, the IV injection system should permit multiple injections over a set time course. Although the mouse hypoxia-induced PAH model is very popular in many laboratories, it is technically challenging to perform multiple IV bolus dosing and invasive hemodynamic assessment in this model. In this protocol, we present step-by-step instructions on how to carry out multiple IV bolus dosing via mouse jugular vein and perform arterial and right ventricle catheterization for hemodynamic assessment in mouse hypoxia-induced PAH model.

This protocol provides a step-by-step procedure for executing multiple intravenous bolus dose administration and invasive hemodynamic monitoring in mice. Investigators can use this protocol for future therapeutic compound screening for pulmonary artery hypertension.

Pulmonary arterial hypertension (PAH) is a progressive life-threatening disease, primarily affecting small pulmonary arterioles of the lung. Currently, ...