EXPRESSION AND LOCALIZATION OF PROSTAGLANDIN EP(3) RECEPTOR MESSENGER-RNA IN THE IMMATURE RABBIT KIDNEY

Arginine vasopressin (AVP)-stimulated cAMP generation is decreased in the immature collecting duct (CD). This is the result of prostaglandin antagonism, most likely via the inhibitory guanine nucleotide-binding protein (G(i)). The EP(3)-subtype prostaglandin E(2) (PGE(2)) recepto r, which is coupled to G(i), could mediate this effect. We studied the developmental expression of EP(3) receptor in the rabbit kidney. High er levels of EP(3) mRNA were observed in the immature kidney using thr ee different assays: I) reverse transcription-polymerase chain reactio n (RT-PCR) with internal standard, 2) competitive PCR, and 3) ribonucl ease protection assay. The highest levels were observed at 2 wk of age . RT-PCB from isolated nephron segments detected EP(3) mRNA in the med ullary thick ascending limb, cortical CD (CCD), and inner medullary CD (IMCD)) of adult and immature kidneys. We conclude that I) renal expr ession of EP(3) mRNA is increased in immature kidneys and 2) EP(3) mRN A is localized in the distal nephron. This suggests that EP(3) recepto r may play a role in the regulation of distal tubular transport during development.