Pseudo-Inductive Behaviour of the Membrane Potential of<i>Chara corallina</i>under Galvanostatic Conditions

Abstract

The membrane potential of Chara corallina Klein ex Willd, em R.D.W. displays an oscillatory behaviour in response to an applied current step. The relative amplitude and the frequency of oscillation of the overshoot increase with the strength of the current. Increasing temperature from 10 °C to 30 °C decreases both the relative overshoot amplitude and the static membrane resistance. The activation energy calculated from the Arrhenius plot of the frequency of the overshoot has a value of 36.1±2.3 kJ mol−1. Raising the external pH from 5.0 to 6.0 decreases the relative amplitude of the overshoot and increases the steady state membrane resistance. Treating the cells for 30 s with 0.1 mol m−3 N-ethylmaleimide induces a rapid fall in both static membrane resistance and overshoot. These results are interpreted in terms of changes in potassium channels conductance.