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

Abstract

Acute Kidney Injury (AKI) is a common, highly lethal, complication of critical illness which has a high mortality [1][2][3][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 Video LinkThe video component of this article can be found at http://www.jove.com/details.php?id=3116 ProtocolAll 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 & Science University Institutional Animal Care and Use Committee. 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. 2. 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. 3. 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°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. 4. 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 im...

Estrogen protects renal endothelial barrier function from ischemia-reperfusion in vitro and in vivo

“…CA/CPR resulted in significant renal injury 24 h following insult, indicated by significant increase in blood urea nitrogen and serum creatinine. Figure 8, A and B, illustrates that serum from 17␤-estradiol-replaced mice contained significantly less urea nitrogen and creatinine compared with ovariectomized, vehicle-treated mice, consistent with our previous observation of estrogen protection of renal function following ischemia (P Ͻ 0.05, n ϭ 8 -12/group) (16,18,20). TRITC-labeled Ficoll was administered to a separate cohort of mice at 2 or 24 h following CA/CPR to assess the effect of ischemia on transglomerular permeability.…”

“…CA/CPR is an established model of renal ischemia-reperfusion injury (7,17,18,20). Although the most extensive in vivo findings about renal ischemia have been derived from focal renal pedicle occlusion models, most human AKI occurs after whole body ischemia-reperfusion (25,46).…”

“…We performed normothermic CA/CPR as previously described (17,18,20). Briefly, after weighing, general anesthesia was induced with 4% isoflurane in Table 1.…”

Extracranial Hypothermia During Cardiac Arrest and Cardiopulmonary Resuscitation Is Neuroprotective In Vivo

“…We performed CA/CPR as previously described with the addition of independent control of intra-and extracranial temperature (Hutchens et al, 2007(Hutchens et al, , 2010(Hutchens et al, , 2011Allen et al, 2011). Briefly, we subjected mice to 8 minutes CA, using active control with warming via a separate temperature control system to keep the brain normothermic during CA for all animals.…”

“…We specifically hypothesized that intra-arrest hypothermia of extracranial organs would reduce extracranial organ injury and that this extracranial protection would subsequently reduce intracranial (i.e., brain) organ injury. To test this hypothesis, we employed a well-characterized mouse model of CA and cardiopulmonary resuscitation (CPR) in which temperature of the brain and other organs can be independently controlled, and in which we have previously demonstrated both neurologic and peripheral organ injury (Hutchens et al, 2007(Hutchens et al, , 2010(Hutchens et al, , 2011Allen et al, 2011).…”