Effect of age on rat aortic responses to acetylcholine and nitric oxide donor (NOC-18).
The purpose of the present study was to examine the effects of age on vascular responses to acetylcholine (ACh) and NO-releasing compound (NOC-18). The studies were performed in young (4 mo old, n = 8) and old (22 mo old, n = 6) male rats. Responses to ACh and NOC-18 were examined in vitro by using isolated abdominal aortic rings. The maximum relaxation response to ACh, an endothelium-dependent vasodilation, was lower in aortas from old rats. Sensitivity (mean effective concentration; EC50) of ACh in old rats was significantly less than in young rats. There were no differences in maximum NOC-18-induced relaxation, an endothelium-independent vasodilation, in aortas from young and old rats. On the other hand, the concentration-response curve for NOC-18 was shifted to the right and the sensitivity (EC50 to NOC-18) was lower in old rats. These results indicated that both endothelium-dependent vasodilation induced by ACh and endothelium-independent vasodilation induced by NOC-18 are impaired in aorta from old rats.
Kano
Y
Y
Department of Applied Physics and Chemistry, The University of Electro-Communications, Chofu, Tokyo, Japan.
Tanabe
T
T
Nagasawa
J
J
Mizuta
T
T
D000109:Acetylcholine / Q000494:pharmacology*; D000375:Aging / Q000502:physiology*; D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000502:physiology; D008297:Male; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009603:Nitroso Compounds / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D014664:Vasodilation / Q000187:drug effects
C093285:NOC 18; D020030:Nitric Oxide Donors; D009603:Nitroso Compounds; D000109:Acetylcholine