Effects of simulated microgravity on nitric oxide level in cardiac myocytes and its mechanism

Prolonged exposure to space microgravity results in cardiovascular deconditioning and the depression of cardiac contractility, while its mechanism is still unknown1]. Thus study about ef-fects of microgravity on cardiac myocytes and related mechanism is an important issue in space medicine. It would also contribute to understanding effects of mechanical signal on signal transduction in cardiac myocytes and pathology of related diseases. Nitric oxide (NO) is a universal signal molecular in ce…

Effects of simulated microgravity on nitric oxide level in cardiac myocytes and its mechanism

The depression of cardiac contractility induced by space microgravity is an important issue of aerospace medicine research, while its precise mechanism is still unknown. In the present study, we explored effects of simulated microgravity on nitric oxide (NO) level, inducible nitric oxide synthase (iNOS) expression and related regulative mechanism using electron spin resonance (ESR) spectroscopy, immunocytochemistry and in situ hybridization. We found a remarkable in-crease of NO level and up-regulation of iNOS and iNOS mRNA expression in rat cardiac myocytes under simulated microgravity. Staurosporine (a nonselective protein kinase inhibitor), calphostin C (a selective protein kinase C inhibitor), partially inhibited the effect of simulated microgravity. Thus regulative effect of simulated microgravity on iNOS expression is mediated at least partially via activation of protein kinase C. These results indicate that NO system in cardiac myocytes is sensi-tive to simulated microgravity and may play an important role in the depression of cardiac contrac-tility induced by simulated microgravity.