title: Characterisation of volume-activated ion transport across epithelial monolayers of human intestinal T84 cells.
abstract: The effects of hypo-osmolarity upon transepithelial ion transport in human intestinal cell layers have been investigated. Exposure of the basal-lateral surfaces to hypo-osmotic media resulted in a transient stimulation of inward short-circuit current (Isc). This transient stimulation of inward current by hypo-osmotic media was abolished by 100 mumol/l 4,4'-diisothiocyanostilbene-2,2'-disulphonic acid (DIDS). After prestimulation of inward Isc by vasoactive intestinal peptide (VIP) or by combinations of carbachol and prostaglandin E1, hypo-osmotic exposure of the basal-lateral surfaces resulted in a further transient stimulation of Isc. The stimulation of Isc in these conditions was largely insensitive to DIDS inhibition. Exposure of the basal-lateral surfaces to hypo-osmotic media resulted in a stimulation of loop-diuretic-insensitive 86Rb efflux across the basal-lateral surfaces. In addition, hypo-osmotic exposure of T84 cells is also associated with an increase in cytosolic Ca2+. It is concluded that the effects of hypo-osmotic exposure of T84 cells on secretory Isc are consistent with the activation of a DIDS-sensitive apical Cl- conductance and a basal-lateral K+ conductance. With prior activation of inward Isc by VIP via a cAMP-activated DIDS-insensitive apical Cl- conductance, augmentation of the secretory current by hypo-osmotic exposure is likely to result primarily from increased basal-lateral K+ current and loop-diuretic-sensitive Cl- uptake.
authors.affiliation: Department of Physiological Sciences, University of Newcastle upon Tyne, UK.
authors.forename: G T
authors.initials: GT
authors.lastname: McEwan
authors.forename: C D
authors.initials: CD
authors.lastname: Brown
authors.forename: B H
authors.initials: BH
authors.lastname: Hirst
authors.forename: N L
authors.initials: NL
authors.lastname: Simmons
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D002217:Carbachol / Q000494:pharmacology; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism; D004553:Electric Conductivity; D004848:Epithelium / Q000378:metabolism; D006801:Humans; D007038:Hypotonic Solutions; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000166:cytology; D007477:Ions; D007700:Kinetics; D009994:Osmolar Concentration; D011458:Prostaglandins E / Q000494:pharmacology; D012414:Rubidium Radioisotopes / Q000378:metabolism; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
chemical_list: D002712:Chlorides; D007038:Hypotonic Solutions; D007477:Ions; D011458:Prostaglandins E; D012414:Rubidium Radioisotopes; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D014660:Vasoactive Intestinal Peptide; D002217:Carbachol; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D002118:Calcium