[Protective effects of nicorandil against catecholamine induced myocardial damage under hypoxia].

Direct myocardial protective effects of Nicorandil (NR) against hypoxic injury were evaluated using an in vitro model of isolated, adult rat myocytes. Ca++-tolerant, trypan blue negative, viable cells were suspended for 1 hour in a hypoxic (Po2 20 mmHg) Eagle's MEM culture medium. Myocytes were then divided into 4 groups and incubated for 3 hours either without (control) or with norepinephrine (NE) (10(-6)M), NR (10(-4)M) or NE+NR. Cell viability ratio (trypan blue staining method) and intracellular ATP contents were measured as indexes of cell damage. NE significantly decreased the cell viability ratio compared to that in control after 1 to 3 hours. Addition of NR prevented the reduction in viability ratio produced by NE. NR markedly attenuated intracellular ATP reduction induced by NE after 1 hour incubation. These results suggest that NR has potent direct effects against hypoxia-induced cell injury in the presence of catecholamines.