Carbachol stimulates Cl- secretion via activation of two distinct apical Cl- pathways in cultured human T84 intestinal epithelial monolayers.
The mode of action of carbachol in stimulation of transepithelial Cl- secretion in intact human intestinal T84 epithelial monolayers has been investigated in order to determine whether a DIDS-insensitive exit pathway (via CFTR) coexists with a DIDS-sensitive exit pathway at the apical membrane. Carbachol stimulates a transient inward Isc due to Cl- secretion whose magnitude is related to the basal level of inward Isc. The inward current responses to both carbachol and hypo-osmotic media are abolished in nominally Ca(2+)-free media. The action of apical DIDS (100 microM) upon carbachol-stimulated Isc depends on the initial value of the basal Isc. At basal Isc levels < 10 microA cm-2, 100 microM DIDS applied to the apical cell border abolishes the inward Isc following exposure to both carbachol and hypo-osmotic media. In contrast a VIP-stimulated inward Isc is observed in the presence of 100 microM DIDS. After VIP stimulation of inward Isc, or if spontaneous basal values of Isc were > 10 microA cm-2, the carbachol stimulation of inward Isc was largely insensitive to 100 microM DIDS. The data are consistent with the participation of both DIDS-sensitive and DIDS insensitive pathways for Cl- at the apical membrane of human intestinal T84 epithelial cells.
McEwan
G T
GT
Department of Physiological Sciences, University of Newcastle upon Tyne, Medical School, UK.
Hirst
B H
BH
Simmons
N L
NL
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology*; D002460:Cell Line; D002712:Chlorides / Q000378:metabolism*; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D006801:Humans; D007038:Hypotonic Solutions; D007422:Intestines; D007700:Kinetics; D008564:Membrane Potentials; D013997:Time Factors; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
D002712:Chlorides; D007038:Hypotonic Solutions; D014660:Vasoactive Intestinal Peptide; D002217:Carbachol; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D002118:Calcium