Effects of calcium antagonists and calmodulin inhibitors on angiotensin II-induced prostaglandin productions in the isolated dog renal arteries.

Angiotensin II markedly potentiated both PGE2 and PGI2 productions in the isolated dog renal arteries. This angiotensin II-induced response was significantly reduced by the treatments of EGTA and calcium antagonists such as verapamil, nifedipine and 8-(N,N'-diethylamino)-octyl-3,4,5,-trimethoxybenzoate (TMB-8). Calmodulin inhibitors, trifluoperazine and W-7 also inhibited the angiotensin II-induced PG productions while an inactive analogue of W-7, W-5 did not have any effect. The results suggest that angiotensin II may enhance the intracellular Ca2+ level through the influx of extracellular Ca2+ and then, calmodulin activated with Ca2+ will stimulate both PGE2 and PGI2 productions via its activation of phospholipase A2 in the dog renal arteries.