Exogenous or endogenous nitric oxide pretreatment induced delayed protection of cardiomyocytes / 中华麻醉学杂志

ABSTRACT

Objective Ischemia preconditioning provides early and delayed protection against ischetnic injury. It has been shown that nitric oxide(NO) exerts protective effects on cardiovascular system. The purpose of this study was to determine if exogenous or endogenous NO pretreatment could provide delayed protection of neonatal rat cardiomyocytes. Methods Neonatal SD rats (1-3 days) were used in this study. Cardiomyocytes obtained from beating heart were cultured and incubated for 72 h. The study was composed of ten groups (1) no medicine was added to the cell medium and the cardiomyocytes were subjected to no hypoxia/reoxygenation (control group);(2) NO donor, S-nitroso-N-acetylpenicillamine (SNAP) 500 ?mol.L-1 was added to cell medium 24 h before H/R( hypoxia 6 h followed by 3 h reoxygenatiori) (SNAP group); (3 )MO precusor, L-arginine 1 mmoL L-1 was added to cell medium 24 h before H/R (L-Arg group); (4) nitric oxide synthase(INOS) antagonist, L-NAME 1 mmol.L-1 and L-arginine 1 mmol.L-1 were added to cell medium 24 h before H/R (L-NAME + L-Arg group); (5) hypoxia preconditioning HP group) in which cultured cells were subjected to 60 min hypoxia followed by 30 min reoxygenation 24 h before H/R; (6) L-NAME 1 mmol.L was added to cell medium during hypoxia preconditioning 24 h before H/R ( L-NAME + HP group) ; (7) cGMP antagonist methylerie blue(MB) 50 ?mol ? L-1 was added to cell medium and one hour later SNAP 500 ?mol?L-1 was added , after being incubated for 24 h the cells were subjected to 6 h hypoxia and 3 h reoxygenation ( MB + SNAP group) ; (8) MB 50 ?mol ? L-1 and L-arginine 1 mmol.L-1 were added to cell medium at 1 h interval 24 h before H/R (MB + L-Arg group); (9) MB 50 ?mol ? L -1 was added to cell medium during hypoxia preconditioning 24 h before H/R (MB + HP group) ; (10) cardiorayocytes underwent 6 h hypoxia and 3 h reoxygenation without any pretreatment (H/R group) . After H/R cardiomyocytes was examined for lactate dehydrogenase ( LDH) activity and cell viability.Results SNAP pretreatment protected cardiomyocytes from H/R injury as shown by reduced LDH activity and improvement in cell viability ( P