Effects of X-irradiation on muscle membrane

Abstract

X-irradiation on frog muscle in the range from 50 to 10,000 r did not produce early changes in the content of sodium or potassium, the permeability of the muscle membrane, ion fluxes, resting and action potentials, membrane resistance or membrane capacitance. This dose range of irradiation did not alter the relationship between resting membrane potential and temperature, nor that between resting membrane potential and external potassium ion concentration. Furthermore, the mechanical responses of frog muscle, such as contraction time, relaxation half time, twitch tension, maximal tetanus tension and optimal stimulus frequency were also unchanged by irradiation of 50 to 10,000 r. The temperature dependence of each of these parameters was studied in detail. On the other hand, preliminary studies now in progress suggested that higher doses (50,000 and 100,000 r) increased significantly the permeability of the muscle membrane to potassium ions.