The effects of capsaicin on the early outward current in identified snail neurones.

An investigation of the action of capsaicin (CAP) on the early outward current (IA) in identified neurones of Helix pomatia was performed using the single electrode clamp. CAP (60-300 microM) caused a dose-dependent reduction of the IA-currents in LPa3 and RPa3 neurones both in normal and Na-free solutions. There was also a marked shortening of the time constant for the inactivation of IA, and a 5-10 mV shift in the hyperpolarizing direction of the curve relating the steady-state inactivation of IA to membrane potential. The equilibrium potential for IA was not changed in up to 300 microM CAP solutions.