Membrane potential plays a dual role for chloride transport across toad skin.
The Cl- -current through toad skin epithelium depends on the potential in a way consistent with a potential-controlled Cl- permeability. Computer analysis of the Koefoed-Johnsen Ussing two-membrane model provided with constant membrane permeabilities indicates that the voltage- and time-dependent currents are not caused by a trivial Goldmand-type rectification and ion redistributions following transepithelial potential pertubations. Extended with a dynamic Cl- permeability in the apical membrane according to a Hodgkin-Huxley kinetic scheme, the model predicts voltage clamp data which closely resemble experimental observations. This extension of the classic frog skin model implies that the Cl- permeability is activated by a voltage change caused by the inward Na+ current through the apical membrane.
D000818:Animals; D001693:Biological Transport, Active; D002023:Bufo bufo; D002462:Cell Membrane / Q000502:physiology; D002712:Chlorides / Q000378:metabolism*; D003201:Computers; D004848:Epithelium / Q000502:physiology; D007700:Kinetics; D008564:Membrane Potentials; D012879:Skin Physiological Phenomena
D002712:Chlorides