title: Properties of an anion-selective channel from rat colonic enterocyte plasma membranes reconstituted into planar phospholipid bilayers.
abstract: Vesicles derived from epithelial cells of the colonic mucosa of the rat were fused to planar phospholipid bilayer membranes, revealing spontaneously switching anion-conducting channels of 50 pS conductance (at -30 mV with 200 mM Cl- each side). The equilibrium selectivity series was I- (1.7)/Br- (1.3)/Cl- (1.0)/F- (0.4)/HCO3- (0.4)/Na (less than 0.11). Only one dominant open-state conductance could be resolved, which responded linearly to Cl- concentrations up to 600 mM. The single-channel current-voltage curve was weakly rectifying with symmetrical solutions. When 50 mV were exceeded at the high-conductance branch of the curve, switching was arrested in the closed state. At more moderate voltages (+/- 40 mV) kinetics were dominated by one open state of about 35-msec lifetime and two closed states of about 2 and 9-msec lifetime. Of these, the more stable closed state occurred less often. At these voltages one additional closed state of significantly longer lifetime (greater than 0.5 sec) was observed.
mesh_terms: D000818:Animals; D000838:Anions; D002462:Cell Membrane / Q000502:physiology; D002712:Chlorides / Q000378:metabolism*; D003106:Colon / Q000166:cytology / Q000502:physiology*; D005260:Female; D007473:Ion Channels / Q000502:physiology*; D007700:Kinetics; D008051:Lipid Bilayers; D008564:Membrane Potentials; D010714:Phosphatidylethanolamines; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D000838:Anions; D002712:Chlorides; D007473:Ion Channels; D008051:Lipid Bilayers; D010714:Phosphatidylethanolamines