ABSTRACT
<p><b>OBJECTIVE</b>To investigate the role of Ca(2+)/calmodulin-dependent calcineurin (CaN) signaling pathway in neuropeptide Y (NPY)-induced cardiomyocyte hypertrophy in rat.</p><p><b>METHODS</b>Cardiomyocytes of neonatal Wistar rats were cultured in the presence of 10 and 100 nmol/L NPY, and cyclosporine A (CsA) was applied to inhibit the activity of CaN. The protein synthesis rate, c-jun mRNA expression, CaN protein expression, CaN activity and intracellular Ca(2+) concentration in the cardiomyocytes were assessed.</p><p><b>RESULTS</b>Compared with the control group, (3)H-Leu incorporation and expression of c-jun mRNA in the cardiomyocytes treated with 100 nmol/L NPY increased significantly (P<0.05, P<0.001), and the effect of NPY was blocked by CsA. The activity of CaN (P<0.05), CaN expression (P<0.05), and Ca(2+) concentration in the cytoplasm (P<0.001) and nuclei (P<0.001) of the cells with 100 nmol/L NPY treatment also significantly increased compared with those in the control cells.</p><p><b>CONCLUSION</b>NPY can induce cardiomyocyte hypertrophy in rats, in which process Ca(2+)/calmodulin-dependent CaN signaling pathway plays an important role.</p>