Hypo-osmolar stimulation of transepithelial Cl- secretion in cultured human T84 intestinal epithelial layers.
Intact epithelial monolayers of T84 human colonic adenocarcinoma cells were exposed from the basolateral surfaces to hypo-osmotic media; in responsive tissues this resulted in a transient stimulation of inward short-circuit current (SCC) to a peak of 12.9 +/- 1.5 (S.E., n = 10) microA/cm2 which declined to prestimulation values of SCC (2.1 microA/cm2) within 5 min. Exposure of T84 cells to hypo-osmotic media results in an increase in cytosolic [Ca2+]i, dependent on extracellular Ca2+ influx. The cell-swelling activated SCC is abolished upon medium Cl- replacement and by 100 microM bumetanide applied to the basal-surfaces, consistent with the inward SCC resulting from transepithelial Cl- secretion. 100 microM DIDS (4,4'-diisothiocyanantostilbene-2,2'-disulphonic acid) also abolished the cell-swelling activated increase in SCC; DIDS is without effect upon the VIP-stimulated SCC, suggesting distinct Cl- channels are involved in the two responses.
McEwan
G T
GT
Department of Physiological Sciences, University of Newcastle upon Tyne, The Medical School, UK.
Brown
C D
CD
Hirst
B H
BH
Simmons
N L
NL
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D002034:Bumetanide / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D018118:Chloride Channels; D002712:Chlorides / Q000378:metabolism*; D003470:Culture Media / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D006801:Humans; D007420:Intestine, Large / Q000187:drug effects / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects; D008565:Membrane Proteins / Q000378:metabolism*; D009994:Osmolar Concentration; D014407:Tumor Cells, Cultured / Q000187:drug effects
D018118:Chloride Channels; D002712:Chlorides; D003470:Culture Media; D008565:Membrane Proteins; D002034:Bumetanide; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D002118:Calcium