The vascular Na+-K+ pump in experimental hypertension.
We assessed the role of putative circulating ouabainlike factor(s) on in vivo arteriolar function in rats with very early (less than 7 days; mean, 3 days) and chronic (greater than 4 weeks) benign, one-kidney, one clip (1K1C) hypertension. Thus, we measured vascular responses in vasodilated (nitroprusside or adenosine), vascularly isolated, innervated hindlimb vascular beds of chloralose-anesthetized 1K1C rats perfused with their own blood at 1 ml/min. Complete norepinephrine dose-response curves in 8 rats with chronic and 28 with early 1K1C hypertension, compared with appropriate normotensive control rats, showed unchanged thresholds and ED50 values. Magnitude of ouabain-induced leftward shifts of the norepinephrine dose-response curve in 18 rats with chronic and 21 with early 1K1C hypertension, compared with appropriate normotensive control rats, was unchanged. Blockade of neural uptake of norepinephrine by desimipramine (10(-7) M) in 8 1K1C rats did not alter these results. These findings provide no evidence in this form and these stages of hypertension that humoral ouabainlike inhibitors of the Na+-K+ pump evoke physiologically significant inotropic effects in arterioles in vivo. It is possible, however, that induction of vascular Na+-K+-adenosine triphosphatase by circulating inhibitors modified the vascular responses to norepinephrine and ouabain in these rats.
Overbeck
H W
HW
Department of Medicine, University of Alabama, Birmingham 35294.
D000818:Animals; D001158:Arteries / Q000201:enzymology*; D001160:Arterioles / Q000187:drug effects / Q000201:enzymology*; D001798:Blood Proteins / Q000494:pharmacology; D002298:Cardenolides; D003891:Desipramine / Q000494:pharmacology; D004077:Digoxin; D006614:Hindlimb / Q000098:blood supply; D006978:Hypertension, Renovascular / Q000201:enzymology*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012503:Saponins; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism*
D001798:Blood Proteins; D002298:Cardenolides; D012503:Saponins; C034504:digoxin-like factors; D010042:Ouabain; D004077:Digoxin; D000254:Sodium-Potassium-Exchanging ATPase; D003891:Desipramine; D009638:Norepinephrine