Prostacyclin and prostaglandin E2 effects on adrenergic transmission in the kidney of anesthetized dog.

The effect of prostaglandin E2 (PGE2) and prostacyclin (PGI2) on the renal venous output of the adrenergic transmitter and on the renal vasoconstriction produced by sympathetic nerve stimulation and by norepinephrine was studied in pentobarbital-anesthetized dog. Renal arterial infusion of either PGE2 or PGI2 (4 ng kg-1 min-1) increased blood flow to the kidney and inhibited the vasoconstrictor response elicited by renal nerve stimulation (1-8 Hz) and by renal arterial injections of norepinephrine (0.006-0.5 microgram). However, during infusion of either PGE2 or PGI2, the renal venous output of norepinephrine caused by nerve stimulation was not altered. In contrast, substance P (2 ng kg-1 min-1), which also increased the blood flow to the kidney, did not affect the renal vasoconstrictor response elicited by either adrenergic stimulus. These results suggest that PGE2 and PGI2 reduce the vasoconstrictor effect of sympathetic nerve stimulation in the canine kidney by acting on the vascular smooth muscle.