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This Article Full Text Full Text (PDF) All Versions of this Article: 296/4/H1164    most recent 00338.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Radhakrishnan, J. Articles by Gazmuri, R. J. Search for Related Content PubMed PubMed Citation Articles by Radhakrishnan, J. Articles by Gazmuri, R. J.

Activation of caspase-3 may not contribute to postresuscitation myocardial dysfunction

Department of Medicine, Division of Critical Care Medicine, and Department of Physiology and Biophysics, Rosalind Franklin University of Medicine and Science; and Medical Service, Section of Critical Care Medicine, North Chicago Veteran Affairs Medical Center, North Chicago, Illinois

Submitted 1 April 2008 ; accepted in final form 18 February 2009

We have previously reported that postresuscitation myocardial dysfunction is accompanied by the release of cytochrome c and caspase-3 activation. We now investigated the role of caspase-3 activation by examining whether such process prompts apoptotic DNA fragmentation, whether caspase-3 inhibition attenuates myocardial dysfunction, and whether myocardial protective effects of sodium-hydrogen exchanger isoform-1 (NHE-1) inhibition involve caspase-3 inhibition using a rat model of ventricular fibrillation (VF) of closed-chest resuscitation. Resuscitation after 4 or 8 min of untreated VF caused significant reductions in left ventricular stroke work index averaging 23% of sham control rats at 4 h postresuscitation. Left ventricular dysfunction was accompanied by increases in cytosolic cytochrome c, decreases in pro- and cleaved caspase-9 fragments, increases in 17-kDa caspase-3 fragments, and increases in caspase-3 activity indicating the activation of the mitochondrial apoptotic pathway but without evidence of apoptotic DNA fragmentation. In addition, levels of heat shock protein 70 were increased and levels of X-linked inhibitor of apoptosis protein and β-crystallin were preserved, all of which can exert antiapoptotic effects. In a separate series, the caspase-3 inhibitor z-Asp-Glu-Val-Asp chloromethyl ketone given before the induction of VF failed to prevent postresuscitation myocardial dysfunction despite reductions in caspase-3 activity (2.3 ± 0.5 vs. 1.3 ± 0.5 pmol fluorophore AFC released·mg protein^–1·min–1; P < 0.03). Treatment with the NHE-1 inhibitor cariporide had no effect on caspase-3 activity. Accordingly, in this rat model of VF and severe postresuscitation myocardial dysfunction, activation of caspase-3 did not lead to DNA fragmentation or contribute to myocardial dysfunction. Concomitant activation of intrinsic antiapoptotic mechanisms could play a protective role downstream to caspase-3 activation.

ventricular fibrillation; cardiopulmonary resuscitation; apoptosis; ventricular function