The effect of ischemic preconditioning on isolated heart beat during ischemia

Objective To investigate the effect of ischemic preconditioning on myocardium during ischemia.Methods Preconditioning was accomplished by three 5-minute global ischemia separated by 10 min intervals of reperfusion.Then 30 min ischemia was followed.Beating time during ischemia was investigated,before and at the end of ischemia.Ventricular muscle samples were taken to determine ATP and Na+-K+-ATPase activity.Results Isolated heart beating time during ischemia in the preconditioning group was longer and the myocardial ATP was more depleted during prolonged ischemia in the preconditioning group than in the control group(P 0.05).Na+-K+-ATPase activity during ischemia between the two groups was not significantly different(P 0.05).Conclusions Preconditioning enhances the myocardial ability to tolerate ischemia and energy utilization.Ischemic preconditioning may prolong isolated heart beating during ischemia.