A specific 70 kDa protein induced in the epileptogenic cortex of rats elicits bursting activity and inactivation of potassium current in snail neurons.

The capability of a specific 70 kDa (P70) protein produced in cobalt-induced epileptogenic cortex of rat cerebrum in promoting epileptic bursting activity was examined in snail neurons, using the voltage clamp method in combination with the pressure injection technique. Injection of P70 into the neurons elicited bursting activity with paroxysmal depolarization shift together with a reduction in the delayed outward current which was suppressed by tetraethylammonium. These changes of membrane properties induced by P70 were dose-dependently inhibited by prior treatment with the anticonvulsant phenytoin. These findings indicate that P70 causes an inactivation of potassium conductance which may generate epileptic bursting activity.