f m Great Britain VOLTAGE CLAMP STUDIES ON INSECT SKELETAL MUSCLE II. THE OUTWARD CURRENTS

Two components of outward currents were investigated under voltage clamp conditions in Tenebrio muscle fibres. The instantaneous current-voltage relation for the transient outward current showed outward rectifi-cation. The tail currents for the delayed outward currents were made up of either one or two exponential components. The activation process for the delayed current was analysed using positive tails that decayed with a simple exponential time course. The delayed current was half-activated at about + 35 mV. Two rate constants for activation are both monotonic functions of membrane potential. The reversal potential for the delayed current was only partially dependent on the external K-concentration. The role of the two outward currents in the production of the action potential was discussed