Effect of long-term treatment with D-NAME and L-NAME with or without L-arginine on cardiovascular system in rats

Hemodynamic parameters, NO synthase activity and myocardial fibrosis were e valuated in male Wistar rats after one month treatment with 40 mg/kg/day of L-NAME, D-NAME, L-arginine 80 mg/kg/day and L-NAME plus 320 mg/kg/day of L -arginine. Myocardial NO synthase activity decreased by 42 and 25 % in the L- and B-NAME groups and by 41 % in the L-NAME with L-arginine group vs, co ntrol. The inhibition of NO synthase was accompanied by a significant eleva tion of systolic blood pressure in the D-NAME and L-NAME with or. without L -arginine groups. There was no significant difference between the control a nd the L-arginine group. Myocardial fibrosis represented approx. 0.94 % in the control, 7.96 % in L-NAME, 5.25 % in D-NAME. 1.36 % in L-NAME with L-ar ginine and 1.05 % in the L-arginine group. The results indicate that B-NAME , although weaker then L-NAME, inhibits NO synthase activity resulting in h emodynamic and structural changes in the cardiovascular system. Although L- arginine prevented tile development of myocardial fibrosis, it did not sign ificantly decrease the NO synthase activity inhibition and systolic blood p ressure.