Intrarenal Role of Angiotensin II: HOMEOSTATIC REGULATION OF RENAL BLOOD FLOW IN THE DOG

• Published in: Circulation research 1973-06, Vol.32 (6), p.692-698
• Main Authors: FREEMAN, RONALD H, DAVIS, JAMES O, VITALE, STEPHEN J, JOHNSON, J Alan
• Format: Article
• Language: English
• Subjects: Alanine - pharmacology; Angiotensin II - antagonists & inhibitors; Angiotensin II - physiology; Animals; Blood Flow Velocity; Blood Pressure - drug effects; Dogs; Female; Homeostasis; Kidney - blood supply; Natriuresis; Norepinephrine - pharmacology; Regional Blood Flow - drug effects; Sarcosine - pharmacology; Vascular Resistance; Vena Cava, Inferior - physiology
• ISSN: 0009-7330; 1524-4571
• DOI: 10.1161/01.RES.32.6.692

The analogue, l-sarcosine-8-alanine-angiotensin II, a specific competitive antagonist of the vascular action of angiotensin II in the rat, blocked the decrease in renal blood flow after a single intrarenal injection of angiotensin II but not after an injection of norepinephrine in normal dogs, in a sodium-depleted dog, and in a dog with thoracic vena caval constriction. Infusion of the analogue at 0.2 μg/kg min into the renal artery consistently increased renal blood flow and decreased renal resistance in both sodium-depleted dogs and dogs with vena caval constriction but did not alter these functions in normal dogs. In five sodium-depleted dogs, renal blood flow increased from an average control value of 196 ± 5 ml/min to 222 ± 11 and 246 ± 12 ml/min after 20 and 40 minutes of antagonist infusion (P < 0.01 and P < 0.005, respectively); renal resistance fell from 0.71 ± 0.03 mm Hg/ml min to 0.62 ± 0.06 and 0.54 ± 0.03 mm Hg/ml min (P < 0.005 for the 40-minute value). In five dogs with vena caval constriction, renal blood flow increased from 143 ± 16 ml/min to 178 ± 23 and 190 ± 19 ml/min after 20 and 40 minutes of analogue infusion (P < 0.02 and P < 0.005, respectively); renal resistance fell from 0.90 ± 0.14 mm Hg/ml min to 0.73 ± 0.14 and 0.64 ± 0.10 mm Hg/ml min (P < 0.01 and P > 0.02, respectively). Mean arterial blood pressure was not altered significantly by the analogue when it was infused at 0.2 μg/kg min. Infusion of the analogue at 2.0μ/kg min decreased arterial blood pressure and renal resistance and increased renal blood flow in five sodium-depleted dogs and in three dogs with vena caval constriction. These observations suggest an important intrarenal role for angiotensin II in the homeostatic regulation of renal blood flow in sodium-depleted dogs and in dogs with vena caval constriction.