Acetylcholine chloride and renal hemodynamics during postnatal maturation in conscious lambs.
To test the hypothesis that acetylcholine-induced relaxation of the renal artery decreases with postnatal age, we measured parameters of renal hemodynamics before and for 35 s after aortic suprarenal injection of acetylcholine in conscious, chronically instrumented lambs aged approximately 1 wk (n = 5) and approximately 6 wk (n = 5). Acetylcholine was administered in one of five doses ranging from 0 to 10 mg/kg body wt; doses were administered randomly, in the same volume. There were significant age- and dose-dependent changes in renal vascular resistance after acetylcholine administration, such that the response was greater in 1-wk-old lambs. After the highest dose tested, renal vascular resistance decreased by 13.6 +/- 7.3 (SD) mmHg. ml(-1). min. g kidney wt in 1-wk-old lambs and by 9.1 +/- 3.2 mmHg. ml(-1). min. g kidney wt in 6-wk-old lambs at 35 s. We also observed a transient renal vasoconstriction before the renal vasodilatation in 6-wk-old lambs but not in 1-wk-old animals. These data provide the first age- and dose-dependent effects of exogenous administration of acetylcholine on renal hemodynamics during maturation in conscious animals.
Sener
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Departments of Physiology and Biophysics and of Medicine, University of Calgary, Calgary, Alberta, Canada T2N 4N1.
Smith
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FG
D000109:Acetylcholine / Q000494:pharmacology*; D000375:Aging / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development*; D001011:Aorta; D004305:Dose-Response Relationship, Drug; D006439:Hemodynamics / Q000187:drug effects; D007269:Injections, Intra-Arterial; D012077:Renal Artery / Q000187:drug effects; D012079:Renal Circulation / Q000187:drug effects; D012756:Sheep; D014655:Vascular Resistance / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
D000109:Acetylcholine