The effect of anxiolytic afobazole (2-[2-morpholino)ethylthio]-5-ethoxybenzimidazole dihydrochloride) at concentrations of 1, 10, 100 and 1000 microM on transmembrane calcium, sodium, and potassium (slow and rapid) ion currents in isolated neurons of Lymnaea stagnalis mollusks have been investigated. Afobazole was found to produce a dose-dependent reversible action: the drug increased all ion currents at concentrations below 100 microM and inhibited all ion currents at concentrations from 100 to 1000 microM. Afobazole at high concentrations accelerated the inactivation of slow potassium ion current and reversibly inhibited the fast potassium ion current.