Localization of prostaglandin E-2 EP2 and EP4 receptors in the rat kidney

We investigated the localization of cAMP-coupled prostaglandin E-2 EP2 and EP4 receptor expression in the rat kidney. EP2 mRNA was restricted to the o uter and inner medulla in rat kidney, as determined by RNase protection ass ay. RT-PCR analysis of microdissected resistance vessels and nephron segmen ts showed EP2 expression in descending thin limb of Henle's loop (DTL) and in vasa recta of the outer medulla. The EP4 receptor was expressed in dista l convoluted tubule (DCT) and cortical collecting duct (CCD) in preglomerul ar vessels, and in outer medullary vasa recta. Butaprost, an EP2 receptor-s elective agonist, dose dependently raised cAMP levels in microdissected DTL and outer medullary vasa recta specimens but had no effect in EP2-negative outer medullary collecting duct segments. Dietary salt intake did not alte r EP2 expression in the kidney medulla. These results suggest that PGE(2) m ay act in the resistance vessels and in the DTL and DCT-CCD segments as a p aracrine, cAMP-dependent regulator of vascular resistance and tubular trans port, respectively.