Small conductance chloride channels in acinar cells from the rat mandibular salivary gland are directly controlled by a G-protein.
This paper reports a 5pS Cl- channel in endpiece cells from the rat mandibular gland. The anion selectivity of the channel was SCN- > (Br- = I-) > NO3- > Cl-, which was similar to whole-cell recordings of a macroscopic anion conductance in these cells. The channel was activated by intracellular Ca2+ at depolarising potentials, with no significant activation when the membrane patch was hyperpolarised. The channel was directly activated by an Al/F complex and GTP gamma S, in separate experiments, applied to the cytosolic face of inside-out excised patches. These G-protein activators stimulated the Cl channel when the Ca2+ concentration was below 1nM, and suggests that this channel may be coupled directly to a G-protein in the apical membrane.
Martin
D K
DK
Department of Physiology, University of Sydney, NSW, Australia.
D000535:Aluminum / Q000494:pharmacology; D000077410:Aluminum Chloride; D017607:Aluminum Compounds; D000818:Animals; D000838:Anions; D002462:Cell Membrane / Q000502:physiology; D018118:Chloride Channels; D002712:Chlorides / Q000378:metabolism / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008565:Membrane Proteins / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012969:Sodium Fluoride / Q000494:pharmacology; D013363:Submandibular Gland / Q000502:physiology*
D017607:Aluminum Compounds; D000838:Anions; D018118:Chloride Channels; D002712:Chlorides; D007473:Ion Channels; D008565:Membrane Proteins; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D000077410:Aluminum Chloride; D012969:Sodium Fluoride; D000535:Aluminum; D019204:GTP-Binding Proteins