Role of nitric oxide in modulating the long-term renal and hypertensive actions of norepinephrine.
We have previously reported that nitric oxide (NO) plays an important role in protecting the renal vasculature from acute norepinephrine-induced vasoconstriction. The purpose of this study was to determine the importance of this interaction between NO and norepinephrine in long-term control of renal hemodynamics and arterial pressure. To achieve this goal, we examined the effects of an intrarenal infusion of norepinephrine (NE) (0.1 microgram.kg-1.min-1) for 7 days in conscious, chronically instrumented control dogs and in dogs pretreated with a synthesis inhibitor, L-NAME (3 micrograms.kg-1.min-1 intrarenally). Both groups of dogs also received captopril (15 micrograms.kg-1.min-1) plus angiotensin I] intravenously to clamp the renin-angiotensin system throughout the protocol. In control dogs (n = 6), intrarenal infusion of NE decreased renal plasma flow by 9% (134 +/- 10 to 122 +/- 14 mL/min) and glomerular filtration rate by 16% (49 +/- 4 to 41 +/- 5 mL/min) while having no effect on mean arterial pressure (100 +/- 3 to 98 +/- 4 mm Hg). In marked contrast, in dogs pretreated with intrarenal L-NAME (n = 9), NE decreased renal plasma flow by 37% (129 +/- 8 to 81 +/- 16 mL/min) and glomerular filtration rate by 32% (47 +/- 3 to 32 +/- 5 mL/min) while increasing mean arterial pressure from 104 +/- 5 to 113 +/- 6 mm Hg. The results of this study demonstrate that NO plays an important role in modulating the long-term actions of NE on renal function and arterial pressure.
Granger
J
J
Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson. JPG@fiona.umsmed.edu
Schnackenberg
C
C
Novak
J
J
Tucker
B
B
Miller
T
T
Morgan
S
S
Kassab
S
S
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D004285:Dogs; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D007668:Kidney / Q000187:drug effects* / Q000502:physiology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009638:Norepinephrine / Q000494:pharmacology*; D012079:Renal Circulation / Q000187:drug effects; D012964:Sodium / Q000378:metabolism
D000316:Adrenergic alpha-Agonists; D009569:Nitric Oxide; D012964:Sodium; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester; D009638:Norepinephrine