Delayed Protective Effect of Norepinephrine Preconditioning on Ischemic/reperfused Myocardium in Isolated Rat Heart

Objective To study the delayed protective effects of norepinephrine preconditioning by express-ing heat shock protein70(HSP70)on reperfused myocardium in isolated rat heart.Methods The study consisted of24Sprague-Dawley rats,which were randomly divided into3groups:control group,E 12h and E 24h group(n=8,respectively).According to the time of norepinephrine(NE)being injected into the belly cavity of the rats,the ex-periment group was divided into2groups:E 12h and E24h group.The levels of CK,LDH and ATP,which indi-cated myocardium injury,and the cardiac function(LVSP and±dp/dt max)were observed in this study.The ex-pression of HSP70was estimated by Western Blot method.Results The expression of HSP70in E 12h group was a little higher than that in control group(P0.05),while that in E 24h group was highest(P0.01).Compared with control group,the levels of LDH and CK in E 24h group were reduced,the ATP content was increased,the cardiac function was improved(P0.01,respectively).Conclusions Norepinephrine preconditioning by highly expressing HSP70has delayed protective effect on reperfused myocardium in isolated rat hearts.