PGE2 stimulates Cl- secretion in murine M-1 cortical collecting duct cells in an autocrine manner.

Prostaglandin E2 (PGE2) is thought to be an important modulator of renal ion and water transport, but its effects remain complex and incompletely understood. Here we examined the effects of PGE2 on transepithelial ion transport of M-1 mouse cortical collecting duct cells using short-circuit current (ISC) measurements. Basolateral addition of PGE2 (1 microM) produced a transient peak increase in ISC of 6.3+/-0.8 microA cm(-2) (n=11), followed by a sustained plateau. The PGE2-evoked response was preserved in the presence of 100 micro M apical amiloride with an average peak increase of 10.6+/-1.0 microA cm(-2) (n=23). However, it was greatly diminished in both the presence of apical diphenylamine-2-carboxylic acid (DPC, 1 mM) and the absence of extracellular Cl-, indicating that Cl- secretion had been stimulated. Basolateral PGE2 induced a concentration dependent response, with an EC50 of about 8 nM. Apical addition of PGE2 elicited an ISC response similar to that observed with basolateral PGE2. Furthermore, apical exposure to arachidonic acid (AA) produced a similar increase in ISC, which could be prevented by the cyclooxygenase inhibitor indomethacin, while AA failed to exert an additional effect in the presence of PGE2. Using RT-PCR, we confirmed the expression of the PGE2 (EP) receptor subtypes EP1, EP3 and EP4 but not of EP2 in cultured M-1 CCD cells. We conclude that M-1 cells express functional cyclooxygenase activity and can generate PGE2 which acts in an autocrine manner, causing Cl- secretion.