Influence of prostaglandin E2, indomethacin, and reserpine on renal vascular responses to nerve stimulation, pressor and depressor hormones.

The effects of prostaglandin E2 (PGE2) indomethacin, and reserpine were evaluated in the rabbit renal vascular bed in situ under conditions of controlled blood flow. Intrarenal infusion of PGE2, 0.03 and 0.3 microgram/min, decreased responses to renal nerve stimulation, intra-arterial norepinephrine, and angiotensin. Responses to nerve stimulation were decreased to a greater extent than responses to norepinephrine. At lower concentrations the effects of PGE2 on pressor responses and on vascular resistance could be separated. Reserpine decreased the histochemical evidence of adrenergic innervation and reduced the response to renal nerve stimulation, enhanced the response to norepinephrine, and was without effect on the response to angiotensin. Indomethacin decreased depressor responses to arachidonic acid, produced a small increase in renal vascular resistance but did not enhance renal pressor responses. The increase in renal vascular resistance after indomethacin was not modified by reserpine pretreatment. Indomethacin enhanced the renal response to bradykinin. These data show that PGE2 possesses the ability to modulate pressor responses in the kidney. However, experiments with indomethacin suggest that endogenous prostaglandins neither modulate pressor responses nor mediate the response of the renal vascular bed to bradykinin. In addition, these data suggest that the increase in renal resistance after indomethacin is not dependent on the adrenergic nervous system.