Comparison of effects of prostaglandins E2 and I2 on rat renal vascular resistance.

Effects of PGE2 and PGI2 on renal vascular resistance (RVR) were compared in anesthetized rats. Renal blood flow and systemic blood pressure were measured before and during infusion of PGE2 (2--2 microgram/min) or PGI2 (1--5 microgram/min) into the aorta just proximal to the renal arteries. Both prostaglandins significantly decreased blood pressure and renal blood flow, but effects on RVR were dissimilar. At low doses, PGI2 reduced RVR in 8 of 10 rats; PGE2 increased it in 5 of 7. At higher doses, PGE2 increased RVR in all rats; during PGI2 infusion RVR did not significantly exceed control at any dose. We conclude that, in the intact rat, PGE2 increases RVR either directly or through potentiation of other constrictor stimuli, while PGI2 tends to reduce RVR and diminish the renal response to other constrictor stimuli. PGI2 is the only prostaglandin found to decrease RVR in the rat.