Involvement of Sulphhydryl Groups in Radiation Damage to the Human Erythrocyte Membrane

Abstract

X-irradiation produces effects on several membrane permeability parameters of human erythrocytes (K⁺, Na⁺, choline⁺ movements; volume; haemolysis) similar to those produced by the sulphhydryl reagent parachloromercuribenzene sulphonate (PCMBS). However, x-irradiation does not alter glucose transport, in contrast to the inhibition resulting from PCMBS treatment. The results of additivity and subtractivity experiments are consistent with the proposal that PCMBS and x-irradiation produce increased K⁺ permeability by acting on common sites (-SH groups) in the membrane. The kinetics of K⁺ efflux at room temperature and the increased rate of K⁺ efflux at low temperature suggest the existence of membrane repair processes. Doses of x-radiation which alter K⁺ permeability also result in the loss of membrane -SH groups, and part of this loss is due to disulphide formation. It is suggested that these changes of -SH groups after x-irradiation are primary events in the alterations of membrane structure leading to the increased K⁺ permeability observed.