Nitric oxide preconditioning induced early protection of cardiomyocytes

AIM To study whether nitric oxide preconditioning induce early protection of neonatal rat cardiomyocytes. METHODS Cultured neonatal rat cardiomyocytes were divided into 6 groups. ①Normal group;②NO group: SNAP(500 μmol·L -1 ) was added to cell medium 1 h before lethal hypoxia/reoxygenation (HR) injury (6 h hypoxia and 3 h reoxygenation); ③HP group: Cells were cultured for 60min hypoxia followed by 30 min reoxygenation to form hypoxia preconditioning before lethal HR injury;④ L NAME+HP group: Nitric oxide synthase antagonist L NAME was added during HP stage;⑤ L Arg group: L arginine was added to cell medium 1h before lethal HR injury;⑥ L NAME+ L Arg group: Both L NAME and L Arg were added to cell medium 1 h before lethal HR injury;⑦H/R group: Cells underwent lethal HR injury without any treatment. Cardiomyocytes injury was detected by lactate dehydrogenase(LDH) activity and cell viability. RESULTS Nitric oxide preconditioning can protect cardiomyocytes by reducing LDH activity and improving cell viability ( P 0 01). Both HP and L Arg preconditioning can also reduce cardiomyocytes HR injury( P 0 01),but this protective role can be inhibited by L NAME. CONCLUSION Both internal and external NO preconditioning can induce early protection of cardiomyocytes.