All procedures described are conducted in accordance with the National Institutes of Health guidelines for the care and use of animals in research and all animal protocols were approved by the Oregon Health &amp; Science University Institutional Animal Care and Use Committee.
1. Surgical Preparation
<ol>
 <li>Weigh the mouse. The procedure described is performed on C57BL/6 mice weighing between 20 and 25 g. Anesthesia is induced in an induction box using 3-4% 
 isoflurane, and subsequently maintained using 1.5-2.5% isoflurane in air/oxygen mixture.</li>
 <li>Lubricate the eyes and position the animal supine on a heating pad. Immobilize 4 extremities using tape. The hind-paws may be taped in a neutral position, 
 however, the forepaws should be secured as near to the chest wall as possible to allow full chest wall excursion during chest compressions.</li>
 <li>Lubricate and place a rectal temperature probe. Temperature is controlled using a heating pad and lamp connected to an electronic temperature controller 
 (Digi-Sense, Cole Parmer, Vernon Hills IL), which is set to maintain 37.0&deg;C. Because it is possible that a temperature gradient within the animal could develop 
 during the no-flow state, it is important that temperature be measured and controlled near the organ of interest.</li>
 <li>Intubate the trachea using a 2.5 cm 22 ga teflon catheter (Insyte-W, BD, Franklin NJ) and the cut distal end of an angled introducer (Frova Introducer, Cook Medical, 
 Bloomington IN). Other methods of tracheal intubation are acceptable, however, use of the angled introducer allows proper positioning of the neck in a slightly 
 extended position, which optimizes surgical exposure for placement of the intravenous catheter. The endotracheal catheter hub is secured with a loop of suture to 
 the incisor and maintained with slight tension to immobilize the head during chest compressions.</li>
 <li>Mechanically ventilate the mouse with a rodent ventilator set to 140 &mu;L, 150 breaths/minute. This is not adjusted for weight as this protocol is always 
 performed in 20-25 g animals. Do not over-deepen anesthesia. Do not set the ventilator to apply end expiratory pressure as this impairs resuscitation.</li>
 <li>Using sterile technique and an operating microscope, place a pre-flushed PE-10 catheter in the jugular vein. Either side may be used, but use of the 
 side closest to the operator reduces the chance of catheter dislodgement during chest compressions or other manipulations. 0.5% bupivicaine, 0.1 mL is infitrated into wound edges to control postoperative pain.</li>
 <li>Secure the PE-10 catheter into the skin closure with cyanoacrylate surgical adhesive.</li>
 <li>Place subcutaneous EKG electrodes and connect to monitoring device. Careful attention to the signal path and maximization of the signal itself is 
 critical to the success of resuscitation. Ensure that all wires are secured to the operating surface, minimize signal crossings, and minimize insulators 
 (like air in hollow needles or stranded wire) within the signal path. Solid needles connected to nonstranded lead wire may be purchased or made in the lab. 
 Once connected, optimize the EKG signal on the monitor.</li>
</ol>
2. Cardiac Arrest
<ol>
 <li>Ensure that the mouse is normothermic, defined as rectal temperature 36.5&deg;C - 37.5&deg;C. Administer 40 &mu;L of room temperature 0.5 M potassium chloride 
 intravenously and observe isoelectric tracing on EKG. Dose adjustment for weight is not necessary within the range 20-25 g. Start arrest timer.</li>
 <li>Disconnect the ventilator. Discontinue the anesthetic vapor. Turn off the heating pad and any other equipment which produces electronic noise that may interfere with EKG monitoring. Place an insulating blanket over the mouse.</li>
 <li>Record temperature every minute during cardiac arrest. If necessary, a heating lamp may be used to bring core temperature up to the normothermic range. During cardiac arrest, prepare supplies and equipment (for example, the epinephrine syringe) for resuscitation. A checklist can be helpful to ensure uninterrupted resuscitation, which is essential for survival.</li>
 <li>After 7 minutes, 30 seconds of cardiac arrest, reconnect the ventilator and increase the rate to 180 breaths/min, keeping the tidal volume at the pre-arrest setting.</li>
 <li>At 8 minutes, initiate chest compressions at 300 BPM. Motion artifact on the EKG can be used to judge CPR rate. Chest compressions should be delivered with the index finger, 5 mm above the xiphoid process and slightly to the left of midline. The chest should be compressed 1/3-1/2 of the anteroposterior distance and full recoil must be allowed between compressions. Finger positioning and optimal compression pressure are absolutely critical. Failure to achieve survival in this model is almost always due to suboptimal CPR.</li>
 <li>Infuse 0.5 mL of epinephrine, diluted to 15 &mu;g/mL, in the first 30 seconds of CPR. Total epinephrine dose is 8-12 &mu;g. Carefully observe the EKG for return of spontaneous circulation (ROSC). Narrow complex QRS complexes are seen between compression artifacts. ROSC usually occurs between 90 seconds and 2 minutes after starting CPR. Resuscitation is abandoned if ROSC does not occur by 3 minutes. Frequent premature ventricular contractions and changes in EKG axis are observed in the first 2 minutes after ROSC, and almost always resolve into steady sinus tachycardia at 2 minutes.</li>
 <li>Record total time of resuscitation and epinephrine dose. Record temperature every minute for 10 minutes after ROSC.</li>
 <li>EKG leads can be removed when spontaneous respiration begins, usually within 12-15 minutes after ROSC.</li>
 <li>Extubate the trachea when spontaneous respiratory rate is &gt;60/min.</li>
 <li>Place the mouse in a recovery cage on a temperature controlled surface set to 37&deg;C for the first 2 hours postprocedure, ensuring easy access to food and water. The cage may then be moved to standard postoperative housing conditions when the mouse has completely recovered from anesthesia and is active.</li>
</ol>
3. Exsanguination/Perfusion-Fixation and Kidney Harvest
<ol>
 <li>24h after CA/CPR, induce anesthesia with isoflurane 3-4% and secure the animal in the supine position on a surgical surface within a fume hood which is appropriate for use with formalin..</li>
 <li>Deepen the anesthetic by gradually increasing the anesthetic vapor concentration to 5% and ensure the mouse is deeply anesthetized as evidenced by cessation of spontaneous respiration.</li>
 <li>Perform a clamshell thoracotomy and exsanguinate the mouse via apical puncture of the cardiac left ventricle according to standard techniques.</li>
 <li>Via the same needle, administer 0.9% saline by slow infusion. To acclerate perfusion/exsanguination, nick the right atrial appendage with scissors. Perform a laparotomy and observe the kidneys. When they are blanched, saline may be changed to 4% formalin for fixation. Kidneys are then embedded in paraffin and stained with Fluoro-jade B for quantification of tubular epithelial necrosis.</li>
</ol>
4. Representative Results:
When CA is induced, mean arterial pressure (MAP) and regional renal blood flow (RRBCF) drop to near zero and remain stable until 
resuscitation begins (Figure 1). 24h after CA/CPR, serum indices of renal function (blood urea nitrogen, BUN and creatinine) are significantly 
elevated relative to sham-operated animals. AST/ALT are also elevated, offering evidence of profound whole-body ischemia (Figure 2). Neutrophil-gelatinase 
associated lipocalin (NGAL), a sensitive indicator of renal ischemic injury is massively upregulated 24h after CA/CPR (Figure 3). Finally, photomicrographs 
demonstrate the patchy, medullary necrosis typical of ischemic renal injury with thinning of tubular epithelium and luminal filling on hematoxylin and eosin stain 
(Figure 4, panel a) and extensive cell death in medullary tubular epithelium when stained with fluoro-jade B (Figure 4, panel b).
<img src="/files/ftp_upload/3116/3116fig1.jpg" alt="Figure 1" /> 
Figure 1. Cardiac arrest induces instant loss of perfusion pressure, represented here as mean arterial pressure (MAP) measured in the femoral artery, 
resulting in near-complete cessation of regional renal cortical blood flow (RRCBF) throughout the period of cardiac arrest (shaded area). Resuscitation with chest 
compressions and epinephrine returns MAP to normal and RRCBF steadily rises in the post resuscitation period. Reprinted with permission from14.
<img src="/files/ftp_upload/3116/3116fig2.jpg" alt="Figure 2" /> 
Figure 2. 24h postprocedure, blood urea nitrogen (BUN), serum creatinine, and the extent of tubular cell death are all significantly 
elevated in animals having undergone CA/CPR as compared with animals treated with a sham procedure. CA/CPR induces a pan-organismal ischemic insult, 
here evidenced by massive elevation of liver-function enzymes alanine amino transferase (ALT) and aspartate aminotransferase (AST) in CA/CPR mice as 
compared with sham-treated animals.
<img src="/files/ftp_upload/3116/3116fig3.jpg" alt="Figure 3" /> 
Figure 3. Western blot performed using polyclonal antibody to neutrophil gelatinase-associated lipocalin (NGAL), a sensitive indicator of renal 
ischemic injury. Urine samples were obtained immediately prior to (&#x201C;pre&#x201D;) and 24h after (&#x201C;24h&#x201D;) CA/CPR in 4 animals (labeled a, b, c, and d above). NGAL is 
massively upregulated in mouse urine after CA/CPR. Reprinted with permission from14.
<img src="/files/ftp_upload/3116/3116fig4.jpg" alt="Figure 4" /> 
Figure 4. A) Hematoxylin and eosin stain of a short axis hilar section of renal tissue 24h after CA/CPR. There is patchy but clear damage to 
medullary and corticomedullary tubules with tubular plugging. Arrows point to damaged tubules with swollen, pyknotic nuclei at the corticomedullary junction. B) Flouro-jade B stain of the same region in the same animal, 24h after CA/CPR. Fluoro-jade B 
stains necrotic cells bright green, showing patchy corticomedullary tubular necrosis. Arrows point to brightly stained damaged tubules at the corticomedullary junction. These findings are substantially similar to renal biopsy findings from humans who develop AKI, and unlike those produced by other animal models of AKI.

<ol>
	<li>Chertow, G. M., Lazarus, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Predictors+of+mortality+and+the+provision+of+dialysis+in+patients+with+acute+tubular+necrosis.+the+auriculin+anaritide+acute+renal+failure+study+group.">Predictors of mortality and the provision of dialysis in patients with acute tubular necrosis. the auriculin anaritide acute renal failure study group.</a> J Am Soc Nephrol. 9, 692-698 (1998).</li><li>Lassnigg, A., Schmidlin, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Minimal+changes+of+serum+creatinine+predict+prognosis+in+patients+after+cardiothoracic+surgery:+A+prospective+cohort+study.">Minimal changes of serum creatinine predict prognosis in patients after cardiothoracic surgery: A prospective cohort study.</a> J Am Soc Nephrol. 15, 1597-1605 (2004).</li><li>Lassnigg, A., Donner, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lack+of+renoprotective+effects+of+dopamine+and+furosemide+during+cardiac+surgery.">Lack of renoprotective effects of dopamine and furosemide during cardiac surgery.</a> J Am Soc Nephrol. 11, 97-104 (2000).</li><li>Metnitz, P. G., Krenn, C. G. <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+acute+renal+failure+requiring+renal+replacement+therapy+on+outcome+in+critically+ill+patients.">Effect of acute renal failure requiring renal replacement therapy on outcome in critically ill patients.</a> Crit Care Med. 30, 2051-2058 (2002).</li><li>Uchino, S., Kellum, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+renal+failure+in+critically+ill+patients:+A+multinational,+multicenter+study.">Acute renal failure in critically ill patients: A multinational, multicenter study.</a> JAMA. 294, 813-818 (2005).</li><li>Mehta, R. L., Pascual, M. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spectrum+of+acute+renal+failure+in+the+intensive+care+unit:+The+PICARD+experience.">Spectrum of acute renal failure in the intensive care unit: The PICARD experience.</a> Kidney Int. 66, 1613-1621 (2004).</li><li>Zager, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Partial,+aortic+ligation:+A+hypoperfusion+model+of+ischemic+acute+renal+failure+and+a+comparison+with+renal+artery+occlusion.">Partial, aortic ligation: A hypoperfusion model of ischemic acute renal failure and a comparison with renal artery occlusion.</a> J Lab Clin Med. 110, 396-405 (1987).</li><li>Zager, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adenine,+nucleotide+changes+in+kidney,+liver,+and+small+intestine+during+different+forms+of+ischemic+injury.">Adenine, nucleotide changes in kidney, liver, and small intestine during different forms of ischemic injury.</a> Circ Res. 68, 185-196 (1991).</li><li>Oliver, J., MacDowell, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+pathogenesis+of+acute+renal+failure+associated+with+traumatic+and+toxic+injury;+renal+ischemia,+nephrotoxic+damage+and+the+ischemic+episode.">The pathogenesis of acute renal failure associated with traumatic and toxic injury; renal ischemia, nephrotoxic damage and the ischemic episode.</a> J Clin Invest. 30, 1307-1439 (1951).</li><li>Phillips, R. A., Dole, V. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+acute+hemorrhage+and+traumatic+shock+on+renal+function+in+dogs.">Effects of acute hemorrhage and traumatic shock on renal function in dogs.</a> Am J Physiol. 145, 314-336 (1945).</li><li>Klocke, R., Tian, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surgical+animal+models+of+heart+failure+related+to+coronary+heart+disease.">Surgical animal models of heart failure related to coronary heart disease.</a> Cardiovasc Res. 74, 29-38 (2007).</li><li>Traystman, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+focal+and+global+cerebral+ischemia.">Animal models of focal and global cerebral ischemia.</a> ILAR J. 44, 85-95 (2003).</li><li>Burne-Taney, M. J., Kofler, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+renal+failure+after+whole+body+ischemia+is+characterized+by+inflammation+and+T+cell-mediated+injury.">Acute renal failure after whole body ischemia is characterized by inflammation and T cell-mediated injury.</a> Am J Physiol Renal Physiol. 285, 87-94 (2003).</li><li>Hutchens, M. P., Nakano, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Estrogen+is+renoprotective+via+a+non-receptor+dependent+mechanism+after+cardiac+arrest+in+vivo.">Estrogen is renoprotective via a non-receptor dependent mechanism after cardiac arrest in vivo.</a> Anesthesiology. 112, 395-405 (2010).</li><li>Hutchens, M. P., Nakano, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Soluble+epoxide+hydrolase+gene+deletion+reduces+survival+after+cardiac+arrest+and+cardiopulmonary+resuscitation.">Soluble epoxide hydrolase gene deletion reduces survival after cardiac arrest and cardiopulmonary resuscitation.</a> Resuscitation. 76, 89-94 (2007).</li><li>Planta, I. v. o. n., Weil, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiopulmonary+resuscitation+in+the+rat.">Cardiopulmonary resuscitation in the rat.</a> J Appl Physiol. 65, 2641-2647 (1988).</li><li>Cobb, L. A., Fahrenbruch, C. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+cardiopulmonary+resuscitation+prior+to+defibrillation+in+patients+with+out-of-hospital+ventricular+fibrillation.">Influence of cardiopulmonary resuscitation prior to defibrillation in patients with out-of-hospital ventricular fibrillation.</a> JAMA. 281, 1182-1188 (1999).</li><li>Aufderheide, T. P., Lurie, K. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Death+by+hyperventilation:+A+common+and+life-threatening+problem+during+cardiopulmonary+resuscitation.">Death by hyperventilation: A common and life-threatening problem during cardiopulmonary resuscitation.</a> Crit Care Med. 32, 345-351 (2004).</li><li>Aufderheide, T. P., Sigurdsson, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyperventilation-induced+hypotension+during+cardiopulmonary+resuscitation.">Hyperventilation-induced hypotension during cardiopulmonary resuscitation.</a> Circulation. 109, 1960-1965 (2004).</li></ol>

No conflicts of interest declared.

The normothermic model of cardiac arrest and cardiopulmonary resuscitation in the mouse offers multiple avenues of evaluation in a model which replicates the pathophysiology and morphology of the most common clinical cause of AKI, whole-body hypoperfusion. Hypothesis testing may be aided by access to a panoply of genetic manipulation techniques and the well-understood and characterized anatomy and physiology of the laboratory mouse.
As described here, survival in experienced hands is 80%. A...

<table border="1">
	<tbody>
		<tr>
			<th>Name of the reagent</th>
			<th>Company</th>
			<th>Catalogue number</th>
		</tr>
		<tr>
			<td>Potassium Chloride</td>
			<td>Abbott Medical</td>
			<td>06653-5</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Abbott Medical</td>
			<td>05260-05 (and others)</td>
		</tr>
		<tr>
			<td>Epinephrine HCl</td>
			<td>Multiple</td>
			<td>Multiple</td>
		</tr>
		<tr>
			<td>Digi-Sense temperature controller</td>
			<td>Cole-Palmer</td>
			<td>EW-89000-00</td>
		</tr>
		<tr>
			<td>Angiocath IV Cath</td>
			<td>VWR</td>
			<td>381134</td>
		</tr>
		<tr>
			<td>Frova angled airway introducer</td>
			<td>Cook</td>
			<td>G27282</td>
		</tr>
		<tr>
			<td>MicroVent Ventilator for Mice</td>
			<td>Harvard Apparatus</td>
			<td>733591</td>
		</tr>
	</tbody>
</table>

normothermic cardiac arrest and cardiopulmonary resuscitation: a mouse model of ischemia-reperfusion injury

Acute Kidney Injury (AKI) is a common, highly lethal, complication of critical illness which has a high mortality1-4 and which is most 
frequently caused by whole-body hypoperfusion.5,6 Successful reproduction of whole-body hypoperfusion in rodent models has been fraught with 
difficulty.7-9,9,10 Models which employ focal ischemia have repeatedly demonstrated results which do not translate to the clinical setting, and larger 
animal models which allow for whole body hypoperfusion lack access to the full toolset of genetic manipulation possible in the mouse.11,12 However, in recent 
years a mouse model of cardiac arrest and cardiopulmonary resuscitation has emerged which can be adapted to model AKI.13 This model reliably reproduces 
physiologic, functional, anatomic, and histologic outcomes seen in clinical AKI, is rapidly repeatable, and offers all of the significant advantages of a murine surgical 
model, including access to genetic manipulative techniques, low cost relative to large animals, and ease of use. Our group has developed extensive experience 
with use of this model to assess a number of organ-specific outcomes in AKI.14,15

Watch this Scientific Journal Video about Normothermic Cardiac Arrest and Cardiopulmonary Resuscitation: A Mouse Model of Ischemia-Reperfusion Injury at JoVE.com

Normothermic Cardiac Arrest and Cardiopulmonary Resuscitation: A Mouse Model of Ischemia-Reperfusion Injury

A powerful model for perioperative and critical care related acute kidney injury is presented. Using whole body hypoperfusion induced by cardiac arrest it is possible to nearly replicate the histologic and functional changes of clinical AKI.

Acute Kidney Injury (AKI) is a common, highly lethal, complication of critical illness which has a high mortality1-4 and which is most 
frequently caused ...

normothermic-cardiac-arrest-cardiopulmonary-resuscitation-mouse-model

Research

JoVE Journal

Medicine

17.9K Views.  Oregon Health & Sciences University. A powerful model for perioperative and critical care related acute kidney injury is presented. Using whole body hypoperfusion induced by cardiac arrest it is possible to nearly replicate the histologic and functional changes of clinical AKI.

Video: Normothermic Cardiac Arrest and Cardiopulmonary Resuscitation: A Mouse Model of Ischemia-Reperfusion Injury

Ischemia-reperfusion Model of Acute Kidney Injury and Post Injury Fibrosis in Mice

Ischemia-reperfusion induced acute kidney injury (IR-AKI) is widely used as a model of AKI in mice, but results are often quite variable with high, often unreported mortality rates that may confound analyses. Bilateral renal pedicle clamping is commonly used to induce IR-AKI, but differences between effective clamp pressures and/or renal responses to ischemia between kidneys often lead to more variable results. In addition, shorter clamp times are known to induce more variable tubular injury, and while mice undergoing bilateral injury with longer clamp times develop more consistent tubular injury, they often die within the first 3 days after injury due to severe renal insufficiency. To improve post-injury survival and obtain more consistent and predictable results, we have developed two models of unilateral ischemia-reperfusion injury followed by contralateral nephrectomy. Both surgeries are performed using a dorsal approach, reducing surgical stress resulting from ventral laparotomy, commonly used for mouse IR-AKI surgeries. For induction of moderate injury BALB/c mice undergo unilateral clamping of the renal pedicle for 26 min and also undergo simultaneous contralateral nephrectomy. Using this approach, 50-60% of mice develop moderate AKI 24 hr after injury but 90-100% of mice survive. To induce more severe AKI, BALB/c mice undergo renal pedicle clamping for 30 min followed by contralateral nephrectomy 8 days after injury. This allows functional assessment of renal recovery after injury with 90-100% survival. Early post-injury tubular damage as well as post injury fibrosis are highly consistent using this model.

We describe models of moderate and severe ischemia-reperfusion-induced kidney injury in which the mice undergo unilateral renal pedicle clamping followed by simultaneous or delayed contralateral nephrectomy, respectively. These models consistently give rise to renal dysfunction and post-injury fibrosis, but injury severity and survival are dependent on mouse background, age and surgical equipment.

Ischemia-reperfusion induced acute kidney injury (IR-AKI) is widely used as a model of AKI in mice, but results are often quite variable with high, often ...

Induction and Assessment of Ischemia-reperfusion Injury in Langendorff-perfused Rat Hearts

The biochemical events surrounding ischemia reperfusion injury in the acute setting are of great importance to furthering novel treatment options for myocardial infarction and cardiac complications of thoracic surgery. The ability of certain drugs to precondition the myocardium against ischemia reperfusion injury has led to multiple clinical trials, with little success. The isolated heart model allows acute observation of the functional effects of ischemia reperfusion injury in real time, including the effects of various pharmacological interventions administered at any time-point before or within the ischemia-reperfusion injury window. Since brief periods of ischemia can precondition the heart against ischemic injury, in situ aortic cannulation is performed to allow for functional assessment of non-preconditioned myocardium. A saline filled balloon is placed into the left ventricle to allow for real-time measurement of pressure generation. Ischemic injury is simulated by the cessation of perfusion buffer flow, followed by reperfusion. The duration of both ischemia and reperfusion can be modulated to examine biochemical events at any given time-point. Although the Langendorff isolated heart model does not allow for the consideration of systemic events affecting ischemia and reperfusion, it is an excellent model for the examination of acute functional and biochemical events within the window of ischemia reperfusion injury as well as the effect of pharmacological intervention on cardiac pre- and postconditioning. The goal of this protocol is to demonstrate how to perform in situ aortic cannulation and heart excision followed by ischemia/reperfusion injury in the Langendorff model.

The isolated rat heart is an enduring model for ischemia reperfusion injury. Here, we describe the process of harvesting the beating heart from a rat via in situ aortic cannulation, Langendorff perfusion of the heart, simulated ischemia-reperfusion injury, and infarct staining to confirm the extent of ischemic insult.

The biochemical events surrounding ischemia reperfusion injury in the acute setting are of great importance to furthering novel treatment options for ...

Murine Model of Intestinal Ischemia-reperfusion Injury

Intestinal ischemia is a life-threatening condition associated with a broad range of clinical conditions including atherosclerosis, thrombosis, hypotension, necrotizing enterocolitis, bowel transplantation, trauma and chronic inflammation. Intestinal ischemia-reperfusion (IR) injury is a consequence of acute mesenteric ischemia, caused by inadequate blood flow through the mesenteric vessels, resulting in intestinal damage. Reperfusion following ischemia can further exacerbate damage of the intestine. The mechanisms of IR injury are complex and poorly understood. Therefore, experimental small animal models are critical for understanding the pathophysiology of IR injury and the development of novel therapies.
Here we describe a mouse model of acute intestinal IR injury that provides reproducible injury of the small intestine without mortality. This is achieved by inducing ischemia in the region of the distal ileum by temporally occluding the peripheral and terminal collateral branches of the superior mesenteric artery for 60 min using microvascular clips. Reperfusion for 1 hr, or 2 hr after injury results in reproducible injury of the intestine examined by histological analysis. Proper position of the microvascular clips is critical for the procedure. Therefore the video clip provides a detailed visual step-by-step description of this technique. This model of intestinal IR injury can be utilized to study the cellular and molecular mechanisms of injury and regeneration.

Here we describe the detailed procedure of intestinal ischemia-reperfusion in mice which results in reproducible injury without mortality to encourage the standardization of this technique across the field. This model of intestinal ischemia-reperfusion injury can be utilized to study the cellular and molecular mechanisms of injury and regeneration.

Intestinal ischemia is a life-threatening condition associated with a broad range of clinical conditions including atherosclerosis, thrombosis, ...

A Mouse Model of Retinal Ischemia-Reperfusion Injury Through Elevation of Intraocular Pressure

Retinal ischemia-reperfusion (I/R) is a pathophysiological process contributing to cellular damage in multiple ocular conditions, including glaucoma, diabetic retinopathy, and retinal vascular occlusions. Rodent models of I/R injury are providing significant insights into mechanisms and treatment strategies for human I/R injury, especially with regard to neurodegenerative damage in the retinal neurovascular unit. Presented here is a protocol for inducing retinal I/R injury in mice through elevation of intraocular pressure (IOP). In this protocol, the ocular anterior chamber is cannulated with a needle, through which flows the drip of an elevated saline reservoir. Using this drip to raise IOP above systolic arterial blood pressure, a practitioner temporarily halts inner retinal blood flow (ischemia). When circulation is reinstated (reperfusion) by removal of the cannula, severe cellular damage ensues, resulting ultimately in retinal neurodegeneration. Recent studies demonstrate inflammation, vascular permeability, and capillary degeneration as additional elements of this model. Compared to alternative retinal I/R methodologies, such as retinal arterial ligation, retinal I/R injury by elevated IOP offers advantages in its&#160;anatomical specificity, experimental tractability, and technical accessibility, presenting itself as a valuable tool for examining neuronal pathogenesis and therapy in the retinal neurovascular unit.

This article describes a procedure for inducing retinal ischemia-reperfusion injury by elevated intraocular pressure in mice. Retinal ischemia-reperfusion injury by elevated intraocular pressure serves to model human pathologies characterized by compromised oxygen and nutrient delivery in the retina, enabling researchers to examine potential cellular mechanisms and treatments for human diseases of the retinal neurovascular unit.

Retinal ischemia-reperfusion (I/R) is a pathophysiological process contributing to cellular damage in multiple ocular conditions, including glaucoma, ...

Ultrasonographic Assessment During Cardiopulmonary Resuscitation

The US-CAB (Ultrasound, Circulation/Airway/Breathing) protocol integrates several sonographic techniques into a structured assessment of the circulation, airway, and breathing status of a patient during cardiopulmonary resuscitation (CPR) in an advanced life support-compliant manner. US-C provides a subxiphoid view of the heart, to look for potentially reversible causes of disease, such as pericardial effusion, pulmonary embolism, hypovolemia, and acute coronary thrombosis. Sonographic cardiac activity during CPR not only helps differentiate pseudo-pulseless electrical activity (PEA) from true PEA but also represents a higher chance of the return of spontaneous circulation (ROSC) and survival. Evaluation of the inferior vena cava (IVC) shows the fluid status of the patient and indicates the best methods to use for fluid resuscitation. If aortic dissection is suspected, a subxiphoid view of the aorta is suggested for identifying an intimal flap. Once intubation is done, tracheal ultrasound (US-A) at the suprasternal notch helps differentiate endotracheal intubation (one air-mucosal interface with one comet-tail) from esophageal intubation (double tract sign). Immediately following US-A, bilateral lung US (US-B) should be done to confirm proper bilateral ventilation using the lung sliding sign. In addition, US-C can be serially followed to see the dynamic changes in the cardiac chambers and IVC, or any cardiac contraction suggestive of ROSC. US-B can also detect coexisting lung or pleural pathologies without interfering with the performance of CPR. The main concern when implementing this method is maintaining high-quality CPR without delays in chest compressions when performing US-CAB. Rigorous training and continued practice are key to minimize any interruptions during resuscitation.

Here, we present a US-CAB (Ultrasound, Circulation/Airway/Breathing) protocol for use during cardiopulmonary resuscitation (CPR). US-C evaluates the subxiphoid view of the heart and inferior vena cava. After intubation, tracheal US (US-A) and lung US (US-B) help confirm endotracheal intubation and proper ventilation.

The US-CAB (Ultrasound, Circulation/Airway/Breathing) protocol integrates several sonographic techniques into a structured assessment of the circulation, ...

A Pre-clinical Rat Model for the Study of Ischemia-reperfusion Injury in Reconstructive Microsurgery

Ischemia-reperfusion injury is the main cause of flap failure in reconstructive microsurgery. The rat is the preferred preclinical animal model in many areas of biomedical research due to its cost-effectiveness and its translation to humans. This protocol describes a method to create a preclinical free skin flap model in rats with ischemia-reperfusion injury. The described 3 cm x 6 cm rat free skin flap model is easily obtained after the placement of several vascular ligatures and the section of the vascular pedicle. Then, 8 h after the ischemic insult and completion of the microsurgical anastomosis, the free skin flap develops the tissue damage. These ischemia-reperfusion injury-related damages can be studied in this model, making it a suitable model for evaluating therapeutic agents to address this pathophysiological process. Furthermore, two main monitoring techniques are described in the protocol for the assessment of this animal model: transit-time ultrasound technology and laser speckle contrast analysis.

Here, we describe a pre-clinical animal model for studying the pathophysiology of ischemia-reperfusion injury in reconstructive microsurgery. This free skin flap model based on the superficial caudal epigastric vessels in the rat may also allow for the evaluation of different therapies and compounds to counteract ischemia-reperfusion injury-related damage.

Ischemia-reperfusion injury is the main cause of flap failure in reconstructive microsurgery. The rat is the preferred preclinical animal model in many ...

Delayed Intramyocardial Delivery of Stem Cells after Ischemia Reperfusion Injury in a Murine Model

There is significant interest in the use of stem cells (SCs) for the recovery of cardiac function in individuals with myocardial injuries. Most commonly, cardiac stem cell therapy is studied by delivering SCs concurrently with the induction of myocardial injury. However, this approach presents two significant limitations: the early hostile pro-inflammatory ischemic environment may affect the survival of transplanted SCs, and it does not represent the subacute infarction scenario where SCs will likely be used. Here we describe a two-part series of surgical procedures for the induction of ischemia-reperfusion injury and delivery of mesenchymal stem cells (MSCs). This method of stem cell administration may allow for the longer viability and retention around damaged tissue by circumventing the initial immune response. A model of ischemia reperfusion injury was induced in mice accompanied by the delivery of mesenchymal stem cells (3.0 x 105), stably expressing the reporter gene firefly luciferase under the constitutively expressed CMV promoter, intramyocardially 7 days later. The animals were imaged via ultrasound and bioluminescent imaging for confirmation of injury and injection of cells, respectively. Importantly, there was no added complication rate when performing this two-procedure approach for SC delivery. This method of stem cell administration, collectively with the utilization of state-of-the-art reporter genes, may allow for the in vivo study of viability and retention of transplanted SCs in a situation of chronic ischemia commonly seen clinically, while also circumventing the initial pro-inflammatory response. In summary, we established a protocol for the delayed delivery of stem cells into the myocardium, which can be used as a potential new approach in promoting regeneration of the damaged tissue.

Stems cells are continuously investigated as potential treatments for individuals with myocardial damage, however, their decreased viability and retention within injured tissue can impact their long-term efficacy. In this manuscript we describe an alternative method for stem cell delivery in a murine model of ischemia reperfusion injury.

There is significant interest in the use of stem cells (SCs) for the recovery of cardiac function in individuals with myocardial injuries. Most commonly, ...

A Rat Lung Transplantation Model of Warm Ischemia/Reperfusion Injury: Optimizations to Improve Outcomes

From our experience with rat lung transplantation, we have found several areas for improvement. Information in the existing literature regarding methods for choosing appropriate cuff sizes for the pulmonary vein (PV), pulmonary artery (PA), or bronchus (Br) are varied, thus making the determination of proper cuff size during rat lung transplantation an exercise of trial and error. By standardizing the cuffing technique to use the smallest effective cuff appropriate for the size of the vessel or bronchus, one can make the transplantation procedure safer, faster, and more successful. Since diameters of the PV, PA, and Br are related to the body weight of the rat, we present a strategy to choosing an appropriate size using a weight-based guide. Since lung volume is also related to body weight, we recommend that this relationship should also be considered when choosing the proper volume of air for donor lung inflation during warm ischemia as well as for the proper volume of PBS to be instilled during bronchoalveolar lavage (BAL) fluid collection. We also describe methods for 4th intercostal space dissection, wound closure, and sample collection from both the native and transplanted lobes.

Here, we present optimizations to a rat lung transplantation model that serve to improve outcomes. We provide a size guide for cuffs based on body weight, a measurement strategy to ascertain the 4th intercostal space, and methods of wound closure and BAL (bronchoalveolar lavage) fluid and tissue collection.

From our experience with rat lung transplantation, we have found several areas for improvement. Information in the existing literature regarding methods ...

An Effective Mouse Model of Unilateral Renal Ischemia-Reperfusion Injury

Ischemia-reperfusion injury (IRI) is the leading cause of acute renal failure and is a significant contributor to delayed graft function. Animal models are the only available resources that mimic the complexities of the IRI-associated damage encountered in vivo. This paper describes an effective mouse model of unilateral renal IRI that delivers highly reproducible data. Ischemia is induced by occluding the right renal pedicle for 30 min followed by reperfusion. In addition to the surgical procedure, a sequential overview of the expected physiological and histopathological changes following renal IRI will be provided by comparing data from seven different reperfusion times (4 h, 8 h, 16 h, 1 day, 2 days, 4 days, and 7 days). Critical data for planning experiments ahead, such as mean surgical time, average anesthetic consumption, and body weight changes over time, will be shared. This work will help researchers implement a reliable renal IRI model and select the appropriate reperfusion time that aligns with their intended investigative goals.

Renal ischemia-reperfusion injury is associated with high morbidity and mortality in hospitalized patients. Here, we present a simple and effective mouse model of unilateral renal ischemia-reperfusion injury and provide a sequential overview of representative pathological changes observed in the kidney.

Ischemia-reperfusion injury (IRI) is the leading cause of acute renal failure and is a significant contributor to delayed graft function. Animal models ...

A Piglet Perinatal Asphyxia Model to Study Cardiac Injury and Hemodynamics after Cardiac Arrest, Resuscitation, and the Return of Spontaneous Circulation

Neonatal piglets have been extensively used as translational models for perinatal asphyxia. In 2007, we adapted a well-established piglet asphyxia model by introducing cardiac arrest. This enabled us to study the impact of severe asphyxia on key outcomes, including the time taken for the return of spontaneous circulation (ROSC), as well as the effect of chest compressions according to alternative protocols for cardiopulmonary resuscitation. Due to the anatomical and physiological similarities between piglets and human neonates, piglets serve as good models in studies of cardiopulmonary resuscitation and hemodynamic monitoring. In fact, this cardiac arrest model has provided evidence for guideline development through research on resuscitation protocols, pathophysiology, biomarkers, and novel methods for hemodynamic monitoring. Notably, the incidental finding that a substantial fraction of piglets have pulseless electrical activity (PEA) during cardiac arrest may increase the applicability of the model (i.e., it may be used to study pathophysiology extending beyond the perinatal period). However, the model generation is technically challenging and requires various skill sets, dedicated personnel, and a fine balance of the measures, including the surgical protocols and the use of sedatives/analgesics, to ensure a reasonable rate of survival. In this paper, the protocol is described in detail, as well as experiences with adaptations to the protocol over the years.

This piglet model involves surgical instrumentation, asphyxiation until the cardiac arrest, resuscitation, and post-resuscitation observation. The model allows for multiple sampling per animal, and by using continuous invasive arterial blood pressure, ECG, and non-invasive cardiac output monitoring, it provides knowledge about hemodynamics and cardiac pathophysiology in perinatal asphyxia and neonatal cardiopulmonary resuscitation.

Neonatal piglets have been extensively used as translational models for perinatal asphyxia. In 2007, we adapted a well-established piglet asphyxia model ...