The present work was to investigate the effects of
vasonatrin peptide (VNP) on cardiomyocyte
protein synthesis induced by moderate
hypoxia. In cultured neonatal rat cardiomyocytes, MTT methods, total
protein measurement and (3)H-leucine incorporation were used to calculate the cell number and measure the
protein synthesis of cardiomyocytes. Furthermore, radioimmunoassay was undertaken to observe the effects of VNP on the intracellular levels of cAMP, cGMP and the concentration of
endothelin (ET) in the culture medium. The results showed that both the cell number and
protein synthesis decreased with severe
hypoxia for 24 h. In contrast, under moderate
hypoxia, cardiomyocyte
hypertrophy developed; the
protein synthesis as evidenced by total
protein content and 3H-eucine incorporation increased significantly. VNP reduced cardiomyocyte
protein synthesis induced by moderate
hypoxia in a dose-dependent manner. Furthermore, VNP increased the intracellular level of cGMP and decreased the concentration of ET in the culture medium under moderate
hypoxia, but had no effect on the level of cAMP. These results suggest that VNP inhibits moderate
hypoxia-induced
protein synthesis in cultured neonatal rat cardiac myocytes. This effect is mediated, at least in part, by an increase in intracellular cGMP, a reduction in synthesis, and/or a release in ET of cardiomyocytes.