Decrease in endothelium dependent hypotension in spontaneously hypertensive rats.
Endothelium-dependent and independent hypotension, vasodilation and relaxation were examined comparatively, in vivo and in vitro, in spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto rats (WKY). In conscious and unrestrained animals, the dose-dependent hypotensive responses to both acetylcholine and adenosine triphosphate (ATP) were attenuated in SHR, compared to findings in the WKY, while sodium nitroprusside lowered mean arterial pressure (MAP), to a similar degree in SHR and WKY. Acetylcholine, ATP and nitroprusside increased the heart rate of SHR and WKY, in a dose-related manner. Mesenteric and femoral blood flow was altered by acetylcholine, ATP and nitroprusside, in a similar manner in the SHR and WKY anesthetized with urethane. However, an ATP-induced reduction in renal blood flow was greater in the SHR than in the WKY. Acetylcholine and nitroprusside led to a concentration-dependent relaxation in the isolated mesenteric artery, to a similar extent in both strains of rats. The relaxation response to acetylcholine was nearly abolished by mechanical removal of the endothelium, but the nitroprusside-induced relaxation was not altered by this denudation. ATP did not influence contraction of the mesentric artery but did produce endothelium-dependent relaxation of aorta, in a dose-dependent manner. All these events suggest that suppression of the endothelium dependent relaxation of resistant arterioles relates to the maintenance of hypertension, in the SHR.
Takata
Y
Y
Second Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Koga
T
T
Kobayashi
K
K
Takishita
S
S
Fujishima
M
M
D000109:Acetylcholine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000502:physiology*; D005263:Femoral Artery / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects; D007022:Hypotension / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D009599:Nitroprusside / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012039:Regional Blood Flow / Q000187:drug effects; D012079:Renal Circulation / Q000187:drug effects; D013152:Splanchnic Circulation / Q000187:drug effects; D014664:Vasodilation / Q000502:physiology
D009599:Nitroprusside; D000255:Adenosine Triphosphate; D000109:Acetylcholine