title: Regulation of Cl- secretion by extracellular ATP in cultured mouse endometrial epithelium.
abstract: The present study explored regulation of electrogenic ion transport across cultured mouse endometrial epithelium by extracellular ATP using the short-circuit current (ISC) and the patch-clamp techniques. The cultured endometrial monolayers responded to apical application of ATP with an increase in ISC in a concentration-dependent manner (EC50 at 3 microM). Replacement of Cl- in the bathing solution or treatment of the cells with Cl- channel blockers, DIDS and DPC, markedly reduced the ISC, indicating that a substantial portion of the ATP-activated ISC was Cl(-)-dependent. Amiloride at a concentration (10 microM) known to block Na+ channels was found to have no effect on the ATP-activated ISC excluding the involvement of Na+ absorption. Adenosine was found to have little effect on the ISC excluding the involvement of P1 receptors. The effect of UTP, a potent P2U receptor agonist on the ISC was similar to that of ATP while potent P2X agonist, alpha-beta-Methylene adenosine 5'-triphosphate (alpha-beta-M-ATP) and P2Y agonist, 2-methylthio-adenosine triphosphate (2-M-ATP), were found to be ineffective. The effect of ATP on ISC was mimicked by the Ca2+ ionophore, ionomycin, indicating a role of intracellular Ca2+ in mediating the ATP response. Confocal microscopic study also demonstrated a rise in intracellular Ca2+ upon stimulation by extracellular ATP. In voltage-clamped endometrial epithelial cells, ATP elicited a whole-cell Cl- current which exhibited outward rectification and delayed activation and inactivation at depolarizing and hyperpolarizing voltages, respectively. The results of the present study demonstrate the presence of a regulatory mechanism involving extracellular ATP and P2U purinoceptors for endometrial Cl- secretion.
authors.affiliation: Department of Physiology, Faculty of Medicine, Chinese University of Hong Kong, Shatin, Hong Kong.
authors.forename: H C
authors.initials: HC
authors.lastname: Chan
authors.forename: C Q
authors.initials: CQ
authors.lastname: Liu
authors.forename: S K
authors.initials: SK
authors.lastname: Fong
authors.forename: S H
authors.initials: SH
authors.lastname: Law
authors.forename: L J
authors.initials: LJ
authors.lastname: Wu
authors.forename: E
authors.initials: E
authors.lastname: So
authors.forename: Y W
authors.initials: YW
authors.lastname: Chung
authors.forename: W H
authors.initials: WH
authors.lastname: Ko
authors.forename: P Y
authors.initials: PY
authors.lastname: Wong
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D018118:Chloride Channels / Q000037:antagonists & inhibitors; D002712:Chlorides / Q000378:metabolism*; D004717:Endometrium / Q000187:drug effects* / Q000378:metabolism*; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D005260:Female; D017136:Ion Transport / Q000187:drug effects; D008564:Membrane Potentials; D051379:Mice; D018613:Microscopy, Confocal; D018408:Patch-Clamp Techniques; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D058473:Receptors, Purinergic P2Y2
chemical_list: D018118:Chloride Channels; D002712:Chlorides; C546386:P2ry2 protein, mouse; D018048:Receptors, Purinergic P2; D058473:Receptors, Purinergic P2Y2; D000255:Adenosine Triphosphate; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D002118:Calcium