Temperature dependence of the four ionic processes of spike electrogenesis in eel electroplaques.

Spike electrogenesis of eel electroplaques involves four ionic processes which are controlled by the membrane potential. A threshold depolarization causes normally closed Na permselective channels to open (Na-activation) and normally open K channels to close (K-inactivation). The Na channels then close (Na-inactivation), and as the spike is terminated, the K channels reopen (K-reactivation). The temperature dependence of these four processes has been examined in the present work. Opening of the Na channels and closure and reopening of the K-channels are either effectively instantaneous or are relatively independent of temperature in the range of at least 5 degrees to 22 degrees. Closure of the Na-channels has a Q10 (increase in rate of reaction for each 10 degrees increase in temperature) of about 9, and activation energy (Ea) of this reaction is about 31.5 kcal/mole (132 kJ/mole).