1978 Volume 42 Issue 8 Pages 927-938
Effects of prostaglandin A2 (PGA2) and E2 (PGE2) on renin release and intrarenal blood flow distribution were studied in dogs anesthetised with pentobarbital. Plasma renin activity (PRA) was measured by radioimmunoassay. Intrarenal distribution of blood flow was determined by means of a radioactive microsphere method. Intrarenal arterial administration (IRA) of PGA2 at a rate of 0.1 μg/min caused an increase in renal blood flow (RBF) and a slight increase in urine flow (UF) without any change of renal arterial pressure (RAP). Renal venous PRA was slightly but significantly increased following PGA2 infusion into the renal artery (0.1 μg/min). Doses of PGA2 (0.5 μg/min, IRA) and PGE2 (0.1 μg/min, IRA) had maximum effect on RBF without changing RAP. Both PGA2 (0.5 μg/min, IRA) and PGE2 (0.1 μg/min, IRA) increased RBF, UF and urinary sodium and potassium excretion, but did not influence on Glomerular filtration rate (GFR). PGA2 (0.5 μg/min, IRA) increased significantly arterial and renal venous PRA while, PGE2 (0.1 μg/min, IRA) had no effect on arterial or renal venous PRA. Concerning the intrarenal distribution of blood flow, both PGA2 (0.5 μg/min, IRA) and PGE2 (0.1 μg/min, IRA) resulted in an increased flow rate in each cortical zone, but the zonal response pattern was not uniform and was characterzed by a progressively proportional increase in flow from the superfical to the deep cortex. Thus, the percentage distribution was significantly changed, showing a redistribution of blood flow from the superficial cortex to the deep cortex. Intravenous administration (IV) of 0.5 μg/min PGA2 reduced blood pressure by 15-20 mmHg but did not change RBF. UF showed a slight decrease following PGA2 infusion intravenously (0.5 μg/min, IV) and increased significantly arterial and renal venous PRA. PGE2 (0.5 μg/min, IV) caused a reduction in RAP by 10-15 mmHg. RBF and UF showed a small increase following PGE2 infusion intravenously (0.5 μg/min). Both arterial and renal venous PRA were increased by intravenous administration of 0.5 μg/min PGE2, but the difference was not significant. The data suggested that both PGA2 and PGE2 have similar effects on renal hemodynamics and urine formation. It is likely that PGA2 stimulates renin release but PGE2 does not.
