1988 年 29 巻 4 号 p. 475-483
The purpose of the present study was to investigate the mechanisms of the hypotensive actions of an angiotensin converting enzyme inhibitor (captopril) in hypertension. In perfused mesenteric vasculatures from spontaneously hypertensive rats (SHR, Okamoto and Aoki strain, 10-13 weeks of age) and agematched normotensive Wistar Kyoto rats (WKY), the effects of captopril on vascular responsiveness and norepinephrine release from the adrenergic nerve endings were examined. The vasoconstrictor responses and norepinephrine release during the electrical nerve stimulation were significantly enhanced in SHR compared to those in agematched WKY. Captopril reduced both vasoconstrictor responses and norepinephrine release during the electrical nerve stimulation, dosedependently. These inhibitory effects of captopril were significantly greater in SHR than in WKY.
The results demonstrate that captopril affects presynaptic sites on the resistance vessels and causes a decrease in electricallystimulated norepinephrine release from the adrenergic nerve endings. The marked reduction of both pressor responses and norepinephrine release by captopril in SHR suggests an enhanced reninangiotensin system in the vascular walls of hypertension.
