Chloride channels in toad skin
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Chloride channels in toad skin. / Larsen, Erik Hviid; Rasmussen, B E.
In: Philosophical Transactions of the Royal Society B: Biological Sciences, Vol. 299, No. 1097, 01.12.1982, p. 413-34.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Chloride channels in toad skin
AU - Larsen, Erik Hviid
AU - Rasmussen, B E
PY - 1982/12/1
Y1 - 1982/12/1
N2 - A study of the voltage and time dependence of a transepithelial Cl- current in toad skin (Bufo bufo) by the voltage-clamp method leads to the conclusion that potential has a dual role for Cl- transport. One is to control the permeability of an apical membrane Cl-pathway, the other is to drive Cl- ions through this pathway. Experimental analysis of the gating kinetics is rendered difficult owing to a contamination of the gated currents by cellular ion redistribution currents. To obtain insight into the effects of accumulation-depletion currents on voltage clamp currents of epithelial membranes, a mathematical model of the epithelium has been developed for computer analysis. By assuming that the apical membrane Cl- permeability is governed by a single gating variable (Hodgkin-Huxley kinetics), the model predicts fairly well steady-state current-voltage curves, the time course of current activations from a closed state, and the dependence of unidirectional fluxes on potential. Other predictions of the model do not agree with experimental findings, and it is suggested that the gating kinetics are governed by rate coefficients that also depend on the holding potential. Evidence is presented that Cl- transport through open channels does not obey the constant-field equation.
AB - A study of the voltage and time dependence of a transepithelial Cl- current in toad skin (Bufo bufo) by the voltage-clamp method leads to the conclusion that potential has a dual role for Cl- transport. One is to control the permeability of an apical membrane Cl-pathway, the other is to drive Cl- ions through this pathway. Experimental analysis of the gating kinetics is rendered difficult owing to a contamination of the gated currents by cellular ion redistribution currents. To obtain insight into the effects of accumulation-depletion currents on voltage clamp currents of epithelial membranes, a mathematical model of the epithelium has been developed for computer analysis. By assuming that the apical membrane Cl- permeability is governed by a single gating variable (Hodgkin-Huxley kinetics), the model predicts fairly well steady-state current-voltage curves, the time course of current activations from a closed state, and the dependence of unidirectional fluxes on potential. Other predictions of the model do not agree with experimental findings, and it is suggested that the gating kinetics are governed by rate coefficients that also depend on the holding potential. Evidence is presented that Cl- transport through open channels does not obey the constant-field equation.
KW - Animals
KW - Biological Transport
KW - Bufo bufo
KW - Chlorides
KW - Cold Temperature
KW - Computers
KW - Electric Conductivity
KW - Ion Channels
KW - Kinetics
KW - Membrane Potentials
KW - Permeability
KW - Skin
KW - Time Factors
M3 - Journal article
C2 - 6130539
VL - 299
SP - 413
EP - 434
JO - Philosophical Transactions of the Royal Society B: Biological Sciences
JF - Philosophical Transactions of the Royal Society B: Biological Sciences
SN - 0962-8436
IS - 1097
ER -
ID: 103931752