[Effect of NOS and PTEN on cardiomyocyte hypertrophy induced by angiotensin II].

Aim: To investigate the effect of NOS and PTEN on the hypertrophic response induced by angiotensin II in the primary culture of neonatal rat cardiomyocytes.

Methods: Total protein content of cardiomyocytes was used as the index of cardiac myocyte hypertrophy. eNOS mRNA, iNOS mRNA and PTEN mRNA expression were assessed using RT-PCR normalized with GAPDH. PTEN protein was determined by Western blot and immunohistochemistry method.

Results: (1) On day 1 after Ang II treatment, the expression of eNOS mRNA was significantly decreased whereas iNOS mRNA expression was significantly increased. The effect of Ang II on NOS expression was inhibited by L-arginine. (2) Total protein content of cardiomyocytes increased significantly on day 5 after Ang II treatment, and PTEN protein expression was significantly decreased. The increased protein content and the decreased expression of PTEN protein were inhibited by L-Arg. The L-arginine effect was blocked by L-NAME(NOS inhibitor). (3) The positive immunocytochemical product of PTEN was mainly located in the nucleus of myocardiocyte.

Conclusion: These results indicate that NOS and PTEN may take part in the process of cardiac myocyte hypertrophy induced by Ang II. The effect of L-arginine on cardiomyocytes may be mediated by NOS/NO and PTEN.