The effect of phloretin on single potassium channels in myelinated nerve.
The effect of phloretin, a dipolar organic compound, on single potassium channel currents of myelinated nerve fibres of Xenopus laevis has been investigated, using inside-out patches prepared by the method of Jonas et al. (1989). The I channel, a potential dependent K channel with intermediate deactivation kinetics, was reversibly blocked by 20 microM phloretin applied on the inside; the block was strongest at negative membrane potentials and less pronounced at positive potentials. Phloretin shifted the curve relating open probability to membrane potential towards more positive potentials and reduced its slope and maximum. This confirms previous findings on the effect of phloretin on the voltage dependence of the fast macroscopic K conductance. Single channel conductance and deactivation kinetics were not altered by phloretin.
Klusemann
J
J
I. Physiologisches Institut, Universität des Saarlandes, Homburg-Saar, Federal Republic of Germany.
Meves
H
H
D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D004553:Electric Conductivity; D066298:In Vitro Techniques; D008564:Membrane Potentials; D009413:Nerve Fibers, Myelinated / Q000187:drug effects* / Q000378:metabolism; D010693:Phloretin / Q000494:pharmacology*; D015221:Potassium Channels / Q000187:drug effects* / Q000378:metabolism; D012584:Sciatic Nerve / Q000187:drug effects / Q000378:metabolism; D014982:Xenopus laevis
D015221:Potassium Channels; D010693:Phloretin