Molecular and cellular biochemistry
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Mol. Cell. Biochem. · Nov 1997
Ischemic preconditioning is not additive to preservation with hypothermia or crystalloid cardioplegia in the globally ischemic rat heart.
The aim of this study was to evaluate the additive protective efficiency of ischemic preconditioning when used in combination with conventional clinically relevant cardioprotective methods of hypothermia or hypothermic cardioplegia during sustained global ischemia. Isolated rat hearts were aorta-perfused with Krebs-Henseleit buffer and were divided into six groups (n = 10 each). Group I: Ischemia at 34 degrees C for 60 min; Group PC + I: preconditioned (PC) ischemia at 34 degrees C, 2 episodes of 5 min ischemia and 10 min reperfusion at 34 degrees C followed by I; Group HI: hypothermic ischemia at 10 degrees C for 60 min; Group PC + HI: preconditioned (PC) hypothermic ischemia, 2 episodes of 5 min ischemia and 10 min reperfusion at 34 degrees C followed by HI; Group CPL + HI: single dose of 'Plegisol' cardioplegia followed by HI; Group PC + CPL + HI: preconditioned hypothermic cardioplegia, followed by CPL + HI. ⋯ This protective effect of preconditioning was possibly mediated by the reduction in the breakdown of purine metabolites. Hypothermia alone or in combination with crystalloid cardioplegia prevented the irreversibility of the ischemic injury but produced contractile and vascular stunning which was not improved by ischemic preconditioning. The results of this study indicate that preconditioning when combined with hypothermia or hypothermic cardioplegia offered no significant additional protection.