|Budget Amount *help
¥3,200,000 (Direct Cost : ¥3,200,000)
Fiscal Year 1998 : ¥1,100,000 (Direct Cost : ¥1,100,000)
Fiscal Year 1997 : ¥2,100,000 (Direct Cost : ¥2,100,000)
Aim of this study is to elucidate the contribution of ATP released from nerve ending to increased vascular tone in the pathogenesis of hypertension. Eight-week-old male Wistar rats, 8-week old male spontaneously hypertensive rats (SHR/Izm) and Wistar-Kyoto rats ( WKY/Izm) were used. Mesenteric arterial preparation was made by Castelluci's methods. Electrical stimulation was made at 0.5Hz, 5msec duration, supra-maximal voltage by platinum electrode attached the sympathetic nerves around mesenteric artery. Exogenous norepinephrine (0.25 mug) was injected to mesenteric artery to evaluate the pressor response. a, , 8-methylene-ATP (2.5x1O^<-6>M) was used as P2x receptor agonist, and suramin (10^<-5>M) was used as P2 antagonist. 0.5Hz of electrical stimulation has no effects on perfusion pressure. 0.5 Hz of electrical stimulation increased norepmephrine-induced pressor response by 162.3% compared with pre-stimulated condition. Blood pressure and body weight of SHR/Izm and WKY/Izm were 174.2mmHg, 139g, 139.OmmHg, 147g, respectively. Pub-pressor frequency of electrical stimulation has no effects on pressor response to norepinephrine in both of SHR/Izm and WKY/Izm. alpha, beta -methylene-ATP increased pressor response to norepinephrine by 128.2% in SHR/Izm, by48.9% in WKY/Izm. ATP released from nerve ending augment the pressor response to norepinephrine through the P2x receptors. In SHR/Izm and WKY/Izm shows no augmented effects of electrical stimulation on pressor response, in contrast, alpha, beta -methylene-ATP has augmented effects on it. These results shows reduced co-release of ATP in SHR/Izm and WKY/Izm.