Objective: The amiloride-sensitive epithelial sodium channel (ENaC) in the aldosterone- sensitive distal nephron is essential for the maintenance of body sodium balance and the long term regulation of blood pressure. Renal prostanoids are thought to be involved in maintaining body fluid and electrolyte homeostasis and may contribute to ENaC regulation. We investigated the role of the most abundant renal prostanoid, Prostaglandin E2 (PGE₂), on ENaC mediated transepithelial sodium transport. Methods: As a model system we used the mouse cortical collecting duct cell line mCCD_cl1. Cells were grown on permeable support and transepithelial ion transport was studied using short circuit current (I_SC) measurements. RT-PCR was used to detect PGE₂ receptor (EP) transcripts. Results: Exposure of mCCD_cl1 cells to basolateral PGE₂ increased I_SC in a dose-dependent manner (IC₅₀ ~2nM). 100 nM PGE₂ rapidly increased I_SC from 8.2 ±0.9 to a plateau of 24.6 ±1.8 mAcm^-2 (n=12; p<0.001). The PGE₂ stimulated I_SC component was inhibited by amiloride which demonstrates that it is mediated by ENaC. The stimulatory response to PGE₂ was preserved in cells pre-stimulated with 3 nM aldosterone. Sulprostone, an agonist of the EP1 and EP3 receptors, had no stimulatory effect. An antagonist of the EP2 receptor (AH6809) did not inhibit the PGE₂ response. In contrast, AH23848, an antagonist of the EP4 receptor, diminished the PGE₂ induced I_SC increase. RT-PCR revealed the presence of EP4 transcripts in these cells. Conclusion: PGE₂ stimulates ENaC mediated transepithelial sodium transport in the mCCD_cl1 cortical collecting duct cells most likely via basolateral EP4 receptors. Thus, PGE₂ may be an important (patho-) physiological modulator of renal ENaC activity.