Effect of Triiodothyronine in Cold Crystalloid Cardioplegia on Cardiac Function and the Function of

bjective:The effect of triiodothyronine at physiological concentration in cold crystalloid cardioplegia on the cardiac function recovery,myocardial enzymogram,oxygen consumption and coronary vascular endothelial function after 90-minute arrest was evaluated.Method:Twelve isolated rat hearts were devided into 2 groups(n=6) with cardioplegia containing 0.6mg/LT3 in experimental group.The isolated working rat heart model was used to measure left ventricular systolic pressure(LVSP),left ventricular+dp/dtmax(LV+dp/dtmax),creatine phosphokinase(CPK) and lactic dehydrogenase(LDH).The acetylcholine-(Ach-) or sodium nitroprusside-SNP induced coronary vasodilation was also measured.Results:Experimental group had a significantly higher recovery of LVSP and LV+dp/dtmax than placebo group did <(90.1±3.7)% vs(66.2±2.1)%;(79.2±5.4)% vs (64.2±6.7)% P<0.05>,respectively.No difference in CPK,LDH,LV-dp/dtmax and Vmo2 was found between two groups.T3 had no effect on Ach-or SNP-induced vasodilation.Conclusion:T3 in cold crystalloid cardioplegia improves LVSP and LV+dp/dtmax recovery and exerts few influence on heart diastolic function,Vmo2 and myocardiac enzymogram.It can't reduce coronary vascular resistance because of the injury or endothelium.