Efficacy Of Myocardial Protection With Optimal Temperature By Cold Blood Cardioplegia

Blood cardioplegia, used with hypothermia, couples the provison of myocardial aerobic metabolism with the capacity to lower myocardial oxygen demands for arrested hearts. However, the proportional protective efficacy attained by optimal hypothermia during blood cardioplegic arrest remains uncertain. To maximize the positive attributes made by cold blood cardioplegia, protective efficacy with optimal myocardial temperature during cardiac arrest was assessed by isolated rat heart.The present study was carried out 1) to investigate the changes in cardiac functional recoveries and myocardial ultrastructure under conditions in which hearts were arrested with cold blood cardioplegia at optimal temperature; 2) to assess the effects of optimal myocardial temperature matained during blood cardioplegic arrset on cardiac sarcoplasmic reticulum(SR) function, determined by SR Ca²⁺ATPase activity , Ca²⁺uptake and net Ca²⁺uptake after Ca²⁺release channel blocked; 3) to understand the molecular mechanism associated with observed changes following cold blood cardioplegic arrest.Part I . Effects of optimal myocardial temperature during cold blood cardioplegic arrest on cardiac SR Ca²⁺ATPase activity and Ca²⁺uptake.In this study, isolated working rat heart was used to evaluate the effect of myocardial temperature in cold cardioplegic arrest on the cardiac functional recoveries, changes in myocardial ultrastructure, SR Ca²⁺ATPase activity and Ca²⁺uptake. Hearts(n=8) were subjected to 120 minutes of cold blood cardioplegic arrest with myocardial temperature maintained at 4 ℃, 8℃, 12 ℃, 16 ℃ and 20 ℃ respectively and followed by 45' reperfusion, whereas 6...