title: Properties of single chloride selective channel from sarcoplasmic reticulum.
abstract: The behavior of single chloride channels in sarcoplasmic reticulum of rabbit and trout skeletal muscle was examined by fusing isolated vesicle fractions into planar lipid bilayers. The channel exhibited a full open state with a unit conductance of 65 pS (in 100 mM Cl-) and several subconductance states with reversal potentials which were dependent on the chloride gradient across the bilayer. Open probability was 0.6-0.95 for membrane potentials ranging from -60 to +60 mV. The kinetic behaviour could be described by assuming one time constant for the fully conducting channel, and at least two time constants for the non-conducting channel. In the presence of methane sulfonate, sulfate and phosphate anions, a decrease in the unit current amplitude but not open time argued in favor of a competition between these anions and Cl- at the transport site of the channel. Chloride channel activity was not affected by variations of Ca2+ concentration in both chambers or by the presence of Mg2+. Similarly, neither millimolar ATP nor the presence of the drugs taurine (up to 10 mM), lidocaine (2-40 microM) or the calmodulin antagonist W7 (5-150 microM), modified channel behavior. Finally, pH variations between 6.8 to 8 were without effect.
authors.affiliation: Department of Biochemistry and Nutrition, School of Medicine, University of North Carolina, Chapel Hill 27599.
authors.forename: E
authors.initials: E
authors.lastname: Rousseau
authors.forename: M
authors.initials: M
authors.lastname: Roberson
authors.forename: G
authors.initials: G
authors.lastname: Meissner
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D018118:Chloride Channels; D002712:Chlorides / Q000502:physiology*; D004553:Electric Conductivity; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008278:Magnesium Sulfate / Q000494:pharmacology; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000502:physiology*; D008698:Mesylates / Q000494:pharmacology; D010710:Phosphates / Q000494:pharmacology; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000502:physiology*; D013431:Sulfates / Q000494:pharmacology; D014337:Trout
chemical_list: D018118:Chloride Channels; D002712:Chlorides; D008565:Membrane Proteins; D008698:Mesylates; D010710:Phosphates; D013431:Sulfates; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D008278:Magnesium Sulfate; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid