An ATP-sensitive potassium channel blocker abolishes the potentiating effect of morphine on the bicuculline-induced convulsion in mice.

ICV bicuculline, a selective GABAA antagonist, dose-dependently induced clonic-tonic convulsions in mice. Coadministration of ICV morphine (mu opioid agonist) significantly potentiated ICV bicuculline-induced convulsions, and this effect of morphine was completely blocked by pretreatment with beta-funaltrexamine (beta-FNA), a mu antagonist. ICV glibenclamide, a selective ATP-sensitive potassium (KATP) channel blocker, at a dose which alone did not affect the convulsive threshold of bicuculline, was capable of blocking the exacerbation of ICV bicuculline-induced convulsions by morphine. The present data further suggest that KATP channels may play a tonic regulatory role in the potentiative effect of morphine on ICV bicuculline-induced convulsions.