We used the short-circuit current technique to investigate the possible facilitatory role of epithelium-derived prostaglandin E2 (PGE2) release on Cl- secretion in the mouse colon. Carbachol- (CCh)-stimulated Cl- secretion was reduced by pretreatment with either indomethacin (10 µM), or TTX (1 µM), and when added together, these inhibitors revealed net CCh-stimulated K+ secretion. CCh-stimulated Cl- secretion was partially restored to TTX/indomethacin-treated colons by addition of a subsecretory concentration of PGE2 (1 nM). In acutely isolated, unstimulated crypt cells, we measured PGE2 release at a similar level. We conclude that autocrine release of PGs from epithelial cells is sufficient to support the CCh-induced Cl- secretory response and is a likely co-factor in this response.