Endothelium-dependent and endothelium-independent vasodilation in resistance arteries from hypertensive rats.
The endothelium-dependent and presumed endothelium-independent vasodilators acetylcholine and sodium nitroprusside, respectively, were used to characterize relaxation responses of mesenteric resistance arteries from stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto rats (WKY). Vessels were preconstricted using concentrations of norepinephrine or 5-hydroxytryptamine, which reduced their diameters by 50 to 60%. Relaxation responses to acetylcholine (10(-8) - 10(-7) M) were significantly smaller (p less than 0.05) in vessel segments from SHRSP, but the maximal relaxations at higher concentrations were the same in both strains. However, SHRSP vessels relaxed to a greater extent than did those of the WKY at all concentrations of sodium nitroprusside. Endothelium removal significantly enhanced sodium nitroprusside-induced dilations in both rat strains, and the dilations were significantly greater in segments from SHRSP in the concentration range of 3 X 10(-8) to 10(-6) M. The decreased relaxation to acetylcholine in resistance arteries from adult hypertensive rats compared with those from the normotensive strain suggests that functional alterations in the endothelium may play a role in hypertensive disease.
Tesfamariam
B
B
Department of Physiology and Biophysics, University of Vermont, College of Medicine, Burlington.
Halpern
W
W
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D004730:Endothelium, Vascular / Q000503:physiopathology*; D006973:Hypertension / Q000503:physiopathology*; D008638:Mesenteric Arteries / Q000503:physiopathology; D009599:Nitroprusside / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012701:Serotonin / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation
D009599:Nitroprusside; D012701:Serotonin; D000109:Acetylcholine; D009638:Norepinephrine