Effect of angiotensin II on myosin heavy chain gene expression in cultured cardiac myocytes of neonatal rat

AIM: MHC (myosin heavy chain)gene molecular phenotype of cultured myocardial cell of neonatal rat in response to AngⅡ (angiotensin Ⅱ)was analyzed.METHODS and RESULTS:(1) Treated cardiac myocytes with 100 nmol/L AngⅡ for 12 hrs increased α-MHC mRNA content by 75% over the control value,and increased β-MHC mRNA slightly by 25%.(2)AngⅡ induced MHC gene expression in a dose-dependent manner in cardiac myocytes.The peak level for α-MHC mRNA expression was observed at 100 nmol/L,and that for β-MHC gene was at 1μmol/L of AngⅡ.(3)The increases in the expression of α-MHC and β-MHC genes induced by AngⅡ were completely blocked by specific AngⅡ-receptor antagnist,Saralasin.CONCLUSION: AngⅡ could induce α-MHC and β-MHC genes expression of cardiac myocytes mediated by AngⅡ receptor.Ang Ⅱ might be an important humoral factor in promoting and maintaining cardiac hypertrophy,independent of secondary hemodynamic effects.