Renal hemodynamic effects of L-NAME during postnatal maturation in conscious lambs.
The purpose of the present study was to investigate the effects of the L-arginine analogue, NG-nitro-L-arginine methyl ester, L-NAME, in modulating renal hemodynamics during postnatal maturation in conscious chronically instrumented lambs. To this end, renal hemodynamic responses to intravenous injection of 10, 20, and 40 mg/kg L-NAME, as well as its inactive enantiomer D-NAME, were measured for 4 h in conscious lambs approximately 1 week (n=10), 3 weeks (n=12), and 6 weeks (n=14) of age. Administration of L-NAME was associated with an increase in renal vascular resistance (RVR) leading to a decrease in renal blood flow. One-week-old lambs were more sensitive to the effects of L-NAME, a marked increase in RVR occurring after the smallest dose administered at 1 week but not at 3 and 6 weeks of age. Renal hemodynamic effects of L-NAME as well as the duration of the responses were also age dependent, such that changes in RVR were greatest and most prolonged in 1-week-old lambs. In addition, a smaller dose of L-NAME was required to attenuate acetylcholine-induced renal vasodilation in lambs aged 1 week compared with older animals. Our data provide new evidence to support the premise that endogenously produced nitric oxide plays a predominant role in regulating renal vascular tone early in life.
Sener
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Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, 3330 Hospital Drive, N.W., Calgary, Alberta, T2N 4N1, Canada.
Smith
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D000375:Aging / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006439:Hemodynamics / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D012079:Renal Circulation / Q000187:drug effects*; D012756:Sheep; D014655:Vascular Resistance / Q000187:drug effects
D004791:Enzyme Inhibitors; D019331:NG-Nitroarginine Methyl Ester