Application of membrane potential equations to tight epithelia

• Published in: The Journal of membrane biology Vol. 120; no. 2; pp. 155 - 163
• Main Authors: GORDON, L. G. M, MACKNIGHT, A. D. C
• Format: Journal Article
• Language: English
• Published: New York, NY Springer 01-03-1991
• Subjects: Animals; Anura; Biological and medical sciences; Biological Transport, Active; Cell Membrane - physiology; Cell Membrane Permeability; Cell physiology; Chlorides - metabolism; Electrophysiology; Epithelium - physiology; Fundamental and applied biological sciences. Psychology; Kinetics; mathematical models; membrane potential; Membrane Potentials - physiology; Models, Biological; Molecular and cellular biology; Potassium - metabolism; Sodium - metabolism; Urinary Bladder - physiology; Ion transport; Stoichiometry; Active transport; Membrane potential; Epithelium; Mathematical model
• ISSN: 0022-2631; 1432-1424
• DOI: 10.1007/BF01872398

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.