EFFECTS OF ISCHEMIC PRECONDITIONING ON THE RELEASE OF CARDIAC TROPONIN-T IN ISOLATED RAT HEARTS

The aim of this study was to examine the effect of ischemic preconditi oning on the releases of cardiac troponin T (TnT) during reperfusion i n isolated rat hearts. Experiments were done on 22 rat hearts, which w ere perfused according to the method of Langendorff and were divided i nto the control group (n = 14) and the preconditioning group (n = 8). Double 5 min of ischemia each followed by 5 min reflow were applied as ischemic preconditioning. After 20 min of global ischemia, the releas es of TnT, creatine kinase (CK), and lactate dehydrogenase (LD) in cor onary effluent and the left ventricular developed pressure (LVP) were measured during 60 min of reperfusion. Ischemic preconditioning signif icantly suppressed the amounts of TnT released during reperfusion, as with those of CK and LD, and also improved contractile dysfunction (ni ne hearts in which ventricular fibrillation was sustained were exclude d from the evaluation for hemodynamics), though the release kinetics o f TnT was different from that of CK and LD. There were good inverse re lationships between the LVP and the total amounts of TnT released duri ng reperfusion period (Sigma TnT) or TnT levels at 60 min of reperfusi on. Cardiac TnT can be used as a useful biochemical marker for hemodyn amics and myocardial damage after reperfusion.