Myocardial vasoactive intestinal peptide and fibrosis induced by nitric oxide synthase inhibition in the rat

Aims: In both normotensive and hypertensive rats, the degree of myocardial fibrosis is inversely correlated with the concentration of vasoactive intestinal peptide (VIP) in the myocardium. Treatment with nitric oxide (NO) synthase inhibitors also causes myocardial fibrosis. In this study, we sought to determine whether the myocardial fibrosis induced by treatment with the NO synthase inhibitor N(G)‐nitro‐l‐arginine methyl ester (l‐NAME) was also associated with depletion of VIP in the myocardium. Methods: Male Wistar Kyoto (WKY) and spontaneous hypertensive rats (SHR) rats treated with l‐NAME were randomized to low, intermediate or high salt content diets. After 4 weeks, the hearts were harvested, the degree of fibrosis quantified and VIP concentration measured. Results: In WKY, systolic blood pressure increased with increasing dietary sodium (P