The A-type potassium current: catechol-induced blockage in snail neurons.

The effects of catechol (1-12.5 mM) on membrane properties, action potential and membrane ionic currents were investigated in identified snail neurons under current- and voltage-clamp conditions. Catechol hardly influenced the resting membrane potential, or the action potential amplitude and duration, but it increased the spike voltage threshold and slightly decreased the input resistance. Catechol specifically decreased the amplitude of the potassium A-currents in a dose-dependent way (Kd = 5 mM), without significant modulation of other potassium currents. The time constants of decay of A-current increased and the steady-state activation or inactivation curve shifted to more positive potentials in the catechol solutions. The blocking effect of catechol on A-currents followed a one-to-one binding stoichiometry (nH = 0.8).