Inhibition of nitric oxide synthase causes cardiac phenotypic modulation in rat.

Abstract Cardiac gene expressions of collagen and contractile proteins were examined in rats treated with a nitric oxide (NO) synthase inhibitor, N G -nitro- l -arginine methyl ester ( l -NAME), for 3 weeks. The rats became hypertensive, which caused left ventricular hypertrophy. Among the mRNAs examined, β-myosin heavy chain was increased and α-myosin heavy chain was decreased in both left and right ventricles, whereas skeletal α-actin and atrial natriuretic polypeptide were increased in the left ventricle only. Furthermore, coadministration of losartan with l -NAME lowered blood pressure and caused regression of left ventricular hypertrophy, but did not affect β- and α-myosin heavy chain mRNA levels, indicating that l -NAME directly regulates β- and α-myosin heavy chain mRNA. © 1997 Elsevier Science B.V. All rights reserved.