title: Angiotensin II stimulation of renal prostaglandin synthesis elevates circulating prostacyclin in the dog.
abstract: The ability of the kidney to release prostacyclin (PGI2) under direct stimulation with exogenous angiotensin II was studied in the pentobarbital-anesthetized dog. We assayed for prostacyclin-like activity in systemic arterial blood by continuously monitoring platelet aggregation in vivo and with the blood-bathed bovine coronary artery, which relaxes to prostacyclin. This parallel bioassay allows detection of small amounts of prostacyclin-like activity released into the systemic circulation. Angiotensin II, infused at a rate of 10 or 20 ng/kg/min into the renal artery inhibited latelet aggregation in 8 out of 18 dogs, relaxed the bovine coronary artery in 13 of 16 dogs, and lowered systemic arterial blood pressure 5-10 mm Hg in all but 3 animals. These effects of antiotensin II could be blocked by treating the animal with indomethacin (2 mg/kg, i.v.) and mimicked by administration of exogenous prostacyclin. Infusion of the same dose of angiotensin II (10 or 20 ng/kg/min) intravenously did not release prostacyclin; blood pressure increased during intravenous infusion, and platelet aggregation remained unchaged. These data are consistent with the hypothesis that prostacyclin, of renal origin in these experiments, can act as a circulating hormone. Prostacyclin should not be regarded only as an antiaggregatory substance, but also as a potentially important modulator of blood pressure.
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects; D004285:Dogs; D011464:Epoprostenol / Q000097:blood*; D007668:Kidney / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism*; D010974:Platelet Aggregation / Q000187:drug effects; D011453:Prostaglandins / Q000096:biosynthesis* / Q000097:blood*; D012039:Regional Blood Flow / Q000187:drug effects
chemical_list: D011453:Prostaglandins; D000804:Angiotensin II; D011464:Epoprostenol