Calcium channel current inactivation is selectively modulated by menthol.

The effect of menthol on Ca channel current inactivation was studied in identified Helix neurons. External application of menthol accelerated the Ca-dependent rapid phase of inactivation. Menthol restored a fast inactivation phase after the Ca-dependent inactivation had been removed by strongly buffering changes in intracellular free Ca or by using Ba ions as current carriers. The menthol-induced inactivation was unchanged by variations in intracellular free Ca. A sensitizing effect of menthol on Ca-dependent inactivation appeared unlikely. Instead the results indicate a modulating action of menthol on Ca inactivation.