Abstract
Objective: We have previously reported in a rat model of VF and closed-chest resuscitation that cytochrome c is released into the bloodstream after resuscitation from cardiac arrest attaining plasma levels inversely proportional to survival. Recent evidence indicates that release of cytochrome c during ischemia and reperfusion may be a manifestation of prolonged opening of the mitochondrial permeability transition pore (mPTP). In this study, we investigated whether cyclosporin A (CsA, an inhibitor of mPTP opening) can prevent post-resuscitation (PR) myocardial dysfunction and improve survival. Methods: VF was electrically induced and left untreated for 10 mins. Resuscitation was attempted by 8 mins of chest compression followed by biphasic waveform defibrillation. Rats were randomized to received a bolus CsA (10 mg/kg) five minutes before inducing VF (n=6), immediately before starting chest compression (n=6), or to receive vehicle control before inducing VF (n=3) or before starting chest compression (n=3). CsA-treated (n=12) and vehicle-treated (n=6) rats were pooled for this analysis after noticing no differences between subgroups. Resuscitated rats were monitored for up to 6 hours. Results: All rats were successfully resuscitated. Treatment with CsA did not improve PR myocardial function (Table ). Survival time was comparable between CsA-treated (321±67 mins) and vehicle-treated (331±67 mins) rats. Conclusions: In our rat model of VF and resuscitation, CsA failed to prevent PR myocardial dysfunction and improve survival. These data contrast with numerous studies demonstrating a protective effect in isolated heart models of ischemia and reperfusion. Two possible explanations are the mPTP does not open in this unique setting of cardiac arrest and resuscitation, and the optimal in vivo dose of CsA needs to be determined as the protective effects of CsA are dose dependent. Hemodynamic and Left Ventricular Function
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