Role of nitric oxide in modulating the vasoconstrictor actions of angiotensin II in preglomerular and postglomerular vessels in dogs.
The purpose of this study was to determine the role of nitric oxide in modulating the vasoconstrictor effect of angiotensin II (Ang II) on renal segmental resistances in the dog. To achieve this objective we examined the effect of intrarenal infusions of Ang II on preglomerular and postglomerular resistances in the presence and absence of intrarenal nitric oxide synthesis inhibition established by an intrarenal infusion of NG-nitro-L-arginine-methyl ester at 5 micrograms/kg per minute in dogs. The whole-kidney stop-flow technique was used. Renal artery pressure was servo-controlled at 78 +/- 2 mm Hg throughout the study. Intrarenal infusion of Ang II alone at 0.5 and 2.0 ng/kg per minute increased renal vascular resistance (delta 0.064 +/- 0.011 and delta 0.171 +/- 0.030 mm Hg/mL per minute, respectively) and decreased renal blood flow (delta 21 +/- 4 and delta 45 +/- 9 mL/min). Associated with these changes, glomerular hydrostatic pressure and preglomerular resistance increased slightly (delta 1.1 +/- 0.9 and delta 1.6 +/- 1.8 mm Hg; delta 0.008 +/- 0.005 and delta 0.030 +/- 0.010 mm Hg/mL per minute, respectively), and postglomerular resistance increased markedly (delta 0.046 +/- 0.011 and delta 0.116 +/- 0.026 mm Hg/mL per minute). When dogs were pretreated with an intrarenal infusion of the nitric oxide synthesis blocker, Ang II at 0.5 and 2.0 ng/kg per minute increased renal vascular resistance (delta 0.271 +/- 0.058 and delta 1.088 +/- 0.242 mm Hg/mL per minute) and decreased renal blood flow (delta 28 +/- 5 and delta 62 +/- 9 mL/min).(ABSTRACT TRUNCATED AT 250 WORDS)
D000804:Angiotensin II / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004285:Dogs; D006874:Hydrostatic Pressure; D007668:Kidney / Q000098:blood supply* / Q000187:drug effects / Q000502:physiology; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000096:biosynthesis / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D012079:Renal Circulation / Q000187:drug effects; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction
D000804:Angiotensin II; D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester