Nonlinear temperature modulation of sodium channel kinetics in GH_3 cells

摘要

The effect of temperature on sodium channel function was examined in GH_3 cells, using the whole cell patch-clamp methodology. Specific parameters examined were current-voltage relationships, activation time, and inactivation time. For the temperature range studied, 23-37 ℃, there was no change in the current-voltage relationship. A linear response to temperature was seen in the inactivation time constant, τ_h. The activation time constant, τ_m, was clearly nonlinear, with a sharp discontinuity at 28 ℃. 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 function obtained at room temperature to physiological temperatures.