It has been proposed that a portion of the biologic actions of vasodilator prostaglandins occurs via an interaction with specific adenylate cyclase-linked receptors. This hypothesis was explored further in the renal microvasculature by examining the effects of PGI₂, PGE₁, and PGE₂ on rabbit preglomerular microvascular adenylate cyclase. A membrane preparation derived from freshly isolated rabbit renal preglomerular microvessels was used in these studies. NaF, forskolin, or 5′-guanylyl imidodiphosphate were found to be effective in increasing adenylate cyclase activity in the absence of exogenous guanosine-5′-triphosphate. A dose-dependent stimulation of adenylate cyclase was also observed with guanosine-5′-triphosphate. PGE₁, PGE₂, and PGI₂ produced a dose-dependent stimulation of adenylate cyclase activity only in the presence of guanosine-5′-triphosphate suggesting that this nucleotide is essential for prostaglandin-induced stimulation of the enzyme. PGI₂ exhibited a time-dependent increase in adenylate cyclase activity and this increased activity reached a plateau at 20–25 min. When PGE₁ and PGE₂ were added together, no additive effect on adenylate cyclase stimulation was noted whereas PGI₂ and PGE₂ when added together produced an additive stimulatory effect. When viewed together, these data suggest the presence of separate PGI₂ and PGE adenylate cyclase-linked receptors in rabbit renal preglomerular microvessels. These findings also suggest that in the renal microvasculature, cyclic AMP may be a second messenger mediating the vasodilatory effects of both PGI₂ and PGE₂.