Nonlinear temperature modulation of sodium channel kinetics in GH(3) cells

The effect of temperature on sodium channel function was examined in GH(3) cells, using the whole cell patch-clamp methodology. Specific parameters ex amined were current-voltage relationships, activation time, and inactivatio n time. For the temperature range studied, 23-37 degreesC, there was no cha nge in the current-voltage relationship. A linear response to temperature w as seen in the inactivation time constant, tau (h). The activation time con stant, tau (m), was clearly nonlinear, with a sharp discontinuity at 28 deg reesC. This nonlinearity was especially evident at lower membrane voltages. These findings are consistent with the hypothesis that membrane structural changes, which occur during the thermotropic phase transition, are capable of influencing the function of the intramembranous portion of the channel. Caution should, therefore, be exercised in extrapolating data on channel f unction obtained at room temperature to physiological temperatures. (C) 200 1 Elsevier Science B.V. All rights reserved.