title: Application of membrane potential equations to tight epithelia.
abstract: It is shown that equations developed to analyze the contributions of secondary active transport processes to symmetrical cells (Gordon, L.G.M., Macknight, A.D.C., 1991, J. Membrane Biol. 120:139-152) can be used, with minor modifications, to analyze the steady-state membrane potential in epithelia under the unique situation of short circuiting. Only under such conditions is there a single intracellular potential relative to both the mucosal and serosal media. The equations are investigated in relation to a model tight epithelium--the toad urinary bladder. It is shown that the properties of the membrane transport pathways are such that the intracellular potential under short-circuit conditions must be more negative than often reported. Given measurements of membrane potential and of voltage-divider ratio, it is possible to use the equations to estimate the absolute values of the membrane permeabilities and conductances under short-circuit conditions.
authors.affiliation: Department of Physiology, University of Otago Medical School, Dunedin, New Zealand.
authors.forename: L G
authors.initials: LG
authors.lastname: Gordon
authors.forename: A D
authors.initials: AD
authors.lastname: Macknight
mesh_terms: D000818:Animals; D001001:Anura; D001693:Biological Transport, Active; D002462:Cell Membrane / Q000502:physiology; D002463:Cell Membrane Permeability; D002712:Chlorides / Q000378:metabolism; D004594:Electrophysiology; D004848:Epithelium / Q000502:physiology*; D007700:Kinetics; D008564:Membrane Potentials / Q000502:physiology*; D008954:Models, Biological; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D001743:Urinary Bladder / Q000502:physiology
chemical_list: D002712:Chlorides; D012964:Sodium; D011188:Potassium