Arteriolar responses to norepinephrine and ouabain in early 1-kidney, 1-clip hypertension in rats

• Published in: The American journal of physiology Vol. 249; no. 4 Pt 2; p. H851
• Main Author: Overbeck, H W
• Format: Journal Article
• Language: English
• Published: United States 01.10.1985
• Subjects: Animals; Dose-Response Relationship, Drug; Hindlimb - blood supply; Hypertension, Renovascular - physiopathology; Ion Channels - physiology; Male; Muscle, Smooth, Vascular - drug effects; Norepinephrine - pharmacology; Ouabain - antagonists & inhibitors; Ouabain - pharmacology; Potassium - metabolism; Rats; Rats, Inbred Strains; Sodium - metabolism; Sodium-Potassium-Exchanging ATPase - metabolism; Time Factors; Vascular Resistance - drug effects
• ISSN: 0002-9513
• DOI: 10.1152/ajpheart.1985.249.4.h851

We assessed the role of putative circulating ouabainlike factors on in vivo arteriolar function in rats with very early (less than or equal to 7 days, mean 3 days), 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 dose-response curves to norepinephrine in 19 1K1C compared with 25 uninephrectomized (1K) normotensive control rats showed unchanged thresholds and 50% effective dosages. Magnitude of ouabain-induced leftward shifts of the dose-response curve in 29 1K1C and 30 1K rats were similar. In 1K1C, compared with 1K, limb resting resistance was elevated by 45% (P less than 0.001), and limb resistance at maximal vasodilation was elevated by 15% (P less than 0.02). These results provide no evidence in this form and stage of hypertension that humoral ouabainlike inhibitors of the sodium-potassium pump evoke physiologically significant inotropic effects in arterioles in vivo. However, the results suggest that significant increases in arteriolar wall-to-lumen ratio occur in the earliest stages (3 days) of hypertension and probably contribute to the elevated resistance.