Breakdown phenomena in the <italic>Chara</italic> membrane

Abstract

The breakdown phenomenon in the Chara internodal cell was studied using the voltage clamp technique. When a slowly hyperpolarizing ramp potential pulse was applied to the Chara membrane, the breakdown occurred with hyperpolarization of about 220 mV. The breakdown was observed by less hyperpolarization, if the external K+ concentration was increased. Such a breakdown phenomenon in the Chara membrane was caused principally by a large shift of the membrane electromotive force toward depolarization. This shift frequently exceeded the peak level of the action potential.