The 70-kDa epileptic cortical protein elicits bursting activity accompanied by a reduction of outward current in Euhadra neurons which is inhibited by an antibody against this protein.

The effect on membrane properties of 70-kDa protein (namely P70), a specific protein found in cobalt-induced epileptic cortex of rats, was examined electrophysiologically in identified neurons of the snail, Euhadra peliomphala. Injection of P70 into the neurons elicited a bursting activity resembling the paroxysmal depolarization shift seen in mammalian epileptic neurons and a reduction of the outward current, which were suppressed by Ca2(+)-free saline or tetraethylammonium. The injection of P70-antibody into neurons, preceding the P70 injection, markedly inhibited the bursting activity and the reduced outward current elicited by P70. These findings suggest that P70 causes a reduction of Ca2(+)-dependent potassium conductance which may be one of the mechanisms generating epileptic bursting activity.