Prostaglandin synthesis by isolated rat glomeruli: effect of angiotensin II

Prostaglandins play a role in the regulation of renal blood flow and glomerular filtration. In the presence of [14C]arachidonate the pattern of prostaglandins produced by isolated glomeruli was PGF2 alpha > PGE2 > PGD2 = TXB2 = 6-keto-PGF1 alpha (a metabolite of prostacyclin). Glomeruli prelabeled with [14C]arachidonate showed an additional labeled prostaglandin that co-chromatographs with 6,15-diketo-13,13-dihydro-PGF1 alpha and may represent breakdown product of prostacyclin. Thus, prostacyclin, judged by its breakdown products, was the second most abundant prostaglandin produced. These results were confirmed by specific radioimmunoassays for PGF2 alpha, PGE2, and 6-keto-PGF1 alpha. Isolated glomeruli produced 1,740 pg x 10 min-1 x mg protein-1 of PGF2 alpha, 798 of 6-keto-PGF1 alpha, and 266 od PGE2. In prelabeled glomeruli angiotensin II causes a small but significant increase in 14C-labeled prostaglandins. Radioimmunoassay for 6-keto-PGF1 alpha showed that the angiotensin stimulation was specific for prostacyclin. Angiotensin II also affected the glomerular handling of [14C]arachidonate. It decreased the uptake of extracellular [14C]arachidonate and increased the incorporation of intracellular [14C]arachidonate into glomerular phospholipids. Based on these results, we propose that in the glomerulus angiotensin increases prostaglandin synthesis and stimulates deacylation and reacylation of phospholipids.