The A-type potassium current: Methoxybenzenes increase the rate of inactivation in snail neurons

Abstract

The effects of anisole (methoxybenzene) and veratrole (1,2-dimethoxybenzene) on the resting membrane potential (RMP), action potential (AP) and membrane potassium currents were investigated in snail neurons under current- and voltage-clamp conditions. Anisole (0.9–3 mM) scarcely influenced the AP, but it moderately depolarized the membrane and increased the neuronal excitability. Anisole accelerated the time-dependent inactivation of the A-current and decreased the time constant of the decay in a dose-dependent way ( K 1 2 = 1.2 mM ). The potential-dependence of the steady-state activation or inactivation of the A-current was not influenced by anisole. An analysis of the Hill plot of anisole action on the time constant of decay of the A-current showed a one-to-two binding stoichiometry ( n H = 2.1). Veratrole (2–8 mM) was effective similarly to anisole on the A-current, but proved less potent.