Effects of angiotensin infusion on renal function in the unanesthetized rat

Abstract

Renal clearances were performed on unanesthetized rats before, during, and after the intravenous infusion of varying doses of angiotensin. Blood pressure increase was linearly related to the log of the dose. Low doses of angiotensin, 20 ng/kg per min, significantly decreased Na excretion and GFR [glomerular filtration rate]. At higher doses, 80-1,000 ng/kg per min, Na excretion was greatly elevated despite diminished GFR. If the rats were infused with 5% glucose or 85 mN NaCl, this natriuretic response was abolished. K excretion, in all animals at all dose levels, was decreased. The decrement in K excretion was not related to Na excretion, but did correlate well with both GFR and RPF [renal plasma flow] reductions. No species difference exists between rat and dog as regards the effects of angiotensin on renal function.