Perfusion of the hearts with DETA/NO blocks caspase activation and necrosis induced by ischemia and ischemia/reperfusion. (A) – caspase activity, (B) – lactate dehydrogenase activity in perfusate. Rat hearts were perfused for 3 min with 50 μM DETA/NO, then hearts were subjected to 30 min ischemia only or to 30 min ischemia plus 30 min reperfusion. Where indicated (KT), hearts were perfused with 1 μM KT5823. Coronary effluents during reperfusion were collected for determination of LDH activity. Cytosolic fractions were separated by differential centrifugation and were used for determination of caspase activity spectrophotometrically using z-DEVD-p-nitroanilide, a caspase-3-substrate. * – Statistically significant effect of ischemia (I) or I/R (p < 0.01, Tukey test) if compared to control; # – statistically significant effect of DETA/NO (p < 0.05, Tukey test) if compared to I or I/R respectively. ^ – statistically significant effect of KT5823 (p < 0.05, LSD test) if compared to I/R + DETA/NO group. Means ± standard errors of 4–9 separate experiments are presented.