Acetylcholine-activated chloride current in the T-84 colonic cell line.
The stimulation of epithelial chloride secretion by hormones and neurotransmitters involves the activation of apical membrane chloride channels. The regulation of chloride current by acetylcholine in the T-84 colonic cell line was investigated using single-channel patch-clamp techniques. Treatment with carbachol resulted in the stimulation of transient chloride currents in 18 of 32 previously quiescent patches. Lack of resolvable single-channel openings suggests that single-channel conductance is less than 5-pS. Of 18 responsive patches, 4 showed multiple current oscillations. Treatment of the cells with AlF4- activated sustained chloride currents, suggesting that G proteins are involved. In excised patches, chloride current was markedly sensitive to free Ca2+ concentrations between 500 and 1000 nM. Time-dependent activation and inactivation of chloride current occurred at +60 and -60 mV. These results indicate that the chloride channels responsible for cholinergic activation of chloride conductance in the T-84 colonic cell line are members of the very low conductance family of chloride channels.
Cliff
W H
WH
Department of Biology, Niagara University, Niagara University, NY 14109, USA.
Duffey
M E
ME
Packianathan
N
N
D000109:Acetylcholine / Q000494:pharmacology*; D017607:Aluminum Compounds / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002460:Cell Line; D018118:Chloride Channels / Q000187:drug effects* / Q000502:physiology*; D003106:Colon / Q000502:physiology*; D004553:Electric Conductivity; D005459:Fluorides / Q000494:pharmacology; D006801:Humans; D015640:Ion Channel Gating; D010277:Parasympathomimetics / Q000494:pharmacology; D018408:Patch-Clamp Techniques
D017607:Aluminum Compounds; D018118:Chloride Channels; D010277:Parasympathomimetics; D002217:Carbachol; D000109:Acetylcholine; D005459:Fluorides; C032311:aluminum fluoride