Effects of Ultraviolet Radiation on the Plasma Membranes of Chara corallina. I The Hyperpolarized State

Abstract

Effects of 254 nm ultraviolet irradiation on the plasmalemma potential difference and conductance in C, corallina have been further analysed. Following an increase in passive chloride permeability, revealed from previous studies, and which is manifested as a depolarization of membrane potential difference and an increase in membrane conductance, a secondary depolarization was prominent at pH 7 and is attributed to u.v.-induced inhibition of an electrogenic pump. The secondary depolarization was usually accompanied by a decrease in membrane conductance. For doses of u.v. of 1400 J m-², these effects were almost reversible within about 1 h