The electromotive force of the <italic>Chara</italic> membrane during the hyperpolarizing response

Abstract

The hyperpolarizing response of the Chara internodal cell was studied by applying the voltage clamp and constant current techniques. By assuming the membrane as an electromotive force (emf) in series with a resistance r (which is the sum of a series resistance rs and the membrane resistance rm), it was shown that the hyperpolarizing response was brought about not only by the increase in membrane resistance but by the increase in membrane emf. The time dependent current-voltage (I–Vm) curve obtained under the voltage clamp during the hyperpolarizing response showed a negative resistance. The hyperpolarizing response is also an excitation, since it is a transition process of the membrane across a negative resistance region.