Effects of intrarenal arterial administration (IRA) of prostaglandin A₂ (PGA₂) and E₂ (PGE₂) on intrarenal blood flow distribution and renin release were studied in dogs anesthetized with pentobarbital. Plasma renin activity (PRA) was measured by radioimmunoassay. Intrarenal distribution of blood flow was determined by means of radioactive microsphere method.
PGA₂ (0.1μg/min, IRA) 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 during PGA₂ infusion into the renal artery (0.1μg/min).
Doses of PGA₂ (0.5μg/min, IRA) and PGE₂ (0.1μg/min, IRA) seemed to be maximum effective ones on RBF without any change of RAP. Both PGA₂ (0.5μg/min, IRA) and PGE₂ (0.1μg/min, IRA) increased RBF, UF and urinary sodium and potassium excretion, but none of them influenced GFR. PGA₂ (0.5μg/min, IRA) increased significantly arterial and renal venous PRA. On the contrary, PGE₂ (0.1μg/min, IRA) had no influence on arterial or renal venous PRA.
Concerning the intrarenal distribution of blood flow, both PGA₂ (0.5μg/min, IRA) and PGE₂ (0.1μg/min, IRA) resulted in an increase of flow rate in each cortex zone. But the zonal response pattern was not uniform, and it was characterized by a progressively proportional increase in flow from the superficial to the deep cortex. Thus, percent distribution was significantly changed showing redistribution of blood flow from the superficial cortex to the deep cortex.
The above results suggest that both PGA₂ and PGE₂ have the almost same effects on renal hemodynamics and urine formation. It is likely that PGA₂ stimulates renin release but PGE₂ dose not.