Trimethadione effects on cholinergic responses in Aplysia neurons

The anticonvulsant, trimethadione (TMO), was tested for effects on cholinergic responses to iontophoretic application of ACh on identified neurons in Aplysia. TMO (1–10 mM) depressed the amplitudes of depolarizing responses mediated by Na⁺ and hyperpolarizing responses mediated by Cl⁻ but did not affect hyperpolarizing responses mediated by K⁺. Such a combination of effects on cholinergic responses distinguishes the action of this anti-absence drug from agents effective against tonic-clonic seizures and from convulsant drugs.