Fast and slow voltage modulation of apical Cl- permeability in toad skin at high [K+].
The influence of voltage on the conductance of toad skin was studied to identify the time course of the activation/deactivation dynamics of voltage-dependent Cl- channels located in the apical membrane of mitochondrion-rich cells in this tissue. Positive apical voltage induced an important conductance inhibition which took a few seconds to fully develop and was instantaneously released by pulse inversion to negative voltage, indicating a short-duration memory of the inhibiting factors. Sinusoidal stimulation at 23.4 mM [Cl-] showed hysteresis in the current versus voltage curves, even at very low frequency, suggesting that the rate of voltage application was also relevant for the inhibition/releasing effect to develop. We conclude that the voltage modulation of apical Cl- permeability is essentially a fast process and the apparent slow components of activation/deactivation obtained in the whole skin are a consequence of a gradual voltage build-up across the apical membrane due to voltage sharing between apical and basolateral membranes.
Procopio
J
J
Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Brasil.
D000818:Animals; D002024:Bufo marinus / Q000502:physiology*; D002463:Cell Membrane Permeability / Q000502:physiology*; D018118:Chloride Channels / Q000502:physiology*; D005712:Galvanic Skin Response; D018408:Patch-Clamp Techniques; D011188:Potassium; D012879:Skin Physiological Phenomena
D018118:Chloride Channels; D011188:Potassium