Renal responses to angiotensin II in conscious dogs: effects of aspirin and indomethacin.

1. Angiotensin II was infused into the renal artery of unanaesthetized dogs at 0.4 and 2.0 ng/kg per min for 40 min each. 2. Indomethacin (3 mg/kg, and 1 mg/kg per h infusion i.v.) accentuated the angiotensin II-induced falls in glomerular filtration rate, renal blood flow and urine flow rate. Indomethacin did not alter the effects of angiotensin II on Na+ or K+ excretions. 3. Aspirin (35 mg/kg p.o. 2.5 h and 0.5 h prior to experiment) did not significantly change the renal effects of angiotensin II. 4. Both aspirin and indomethacin accentuated renal vasoconstriction during briefer (5 min) angiotensin II infusion. 5. Thus indomethacin and aspirin had markedly different effects on the actions of angiotensin II in the kidney. This suggests that at least one of these drugs has actions which affect angiotensin II-mediated vasoconstriction other than via cyclooxygenase inhibition.