Sensitivity of enzymatic release due to ischemia in the isolated rat heart.

The sensitivity of cardiac enzymes (GOT, a-HBDH, LDH, LDH-1, CPK and CPK-MB) was studied in the isolated rat heart subjected to 0 (non-ischemic), 20, 30 and 40 min of total global ischemia (0 ml/min) followed by reperfusion in which three consecutive perfusate samples were collected for enzymatic measurements. Cardiac function, estimated by peak tension (Tp), maximal rate of tension development (Tc) and relaxation (Tr) decreased to 0 with ischemia and recovered with reperfusion to 100% in the 20 min, 50% in the 30 min and 10% in the 40 min ischemic groups. In these three groups, enzymatic release, measured as the relative increment (RI) with respect to the control samples, gave significantly higher values than those of non-ischemic hearts (P less than 0.001). LDH-1 was the most sensitive enzyme (P less than 0.0005) for the detection of ischemia in these experimental conditions.