Volume 67, Issue 1 p. 41-55
Article
Free Access

TEMPERATURE DEPENDENCE OF THE SODIUM CHANNEL GATING KINETICS IN THE NODE OF RANVIER

Carol A. Collins

Carol A. Collins

Department of Biophysics, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ

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E. Rojas

E. Rojas

Department of Biophysics, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ

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First published: 22 January 1982
Citations: 46

Abstract

Temperature dependence of the Na+ channel gating kinetics was measured from the ionic and charge displacement currents in the node of Ranvier of Xenopus laevis. m3h kinetics was applied, assuming a delay, δt, in the activation process. The rate constants for the m- and h-process showed Arrhenius temperature-dependence with Q10 of 2·34 and 2·9 respectively, while δt exhibited non-Arrhenius temperature-dependence. Q10 for [unknown]PNa, measured as 1·6, was smaller than for the rate constants and similar to that for a diffusion process. A negative shift and decrease in voltage sensitivity of the steady-state curves, h and m, occurred with decreasing temperature. The maximum time constant obtained from a single exponential fit to the displacement currents during the pulse for times greater than 90 µs exhibited Q10 of 2·01, which lies between that for [unknown]PNa and that for τm.