Age‐related Changes in Nitric Oxide‐mediated Vasodilation of Cerebral Arteries from Newborn Piglets

Abstract

This study analyses the age-related changes on the vasodilation mediated by endothelial nitric oxide (NO) in rings of cerebral anterior and communicating arteries from 1–3- (Group 1) or 7–10- (Group 2) day-old piglets. Rings were contracted with phenylephrine (10−5 M) in the presence of indomethacin (10−4 M); then, concentration-response curves to bradykinin (10−10–10−6 M) and to exogenous NO (10−9–10−5 M) were performed. The incubation of segments with L-arginine (10−4 M) or NG-nitro-L-arginine methylester (L-NAME; 3 times 10−5 M) decreased and increased, respectively, the phenylephrine-induced contraction; L-NAME enhanced the basal tension also. Bradykinin relaxation was greater in Group 1 than in Group 2. In Group 1, the incubation with L-arginine did not increase bradykinin relaxation, but incubation with L-NAME abolished it. In Group 2, L-Arginine augmented and L-NAME reduced, but did not abolish, bradykinin relaxation. Vasodilatory response to exogenous NO was higher in Group 1 than in Group 2. We conclude that there is a basal and stimulated NO formation in endothelial cells of newborn piglet cerebral arteries, that the stimulated NO production and the sensitivity to NO are higher in vessels from 1–3-day-old piglets, and that L-arginine supplementation can increase the NO production in the vasculature of 7–10-day-old piglets to overcome its lowest sensitivity to NO.