Alterations in Skeletal Muscle after X-Irradiation and their Similarity to Changes in Muscular Dystrophy

Abstract

ALTHOUGH muscle constitutes almost half the body-weight in mammals, it is generally thought to be very radioresistant and to play an insignificant part in the bodily changes which follow irradiation. In excised frog muscle, changes in the resting transmembrane potential and electrolyte composition were found only after massive doses of X-rays^1,2. However, transient weakness and increased fatigability have been observed in man and animals after modest doses of radiation^3,4. Caster and Armstrong⁵ found a large negative potassium balance in rats after an LD₅₀ of X-rays. The lost potassium appeared to originate principally in muscle. A transient post-irradiation aldolasæmia⁶ also occurs as well as an amino-aciduria and creatinuria^7–9 which appears to be linearly dependent on the dose of radiation¹⁰. It seems likely that the creatine and other amino-acids and the aldolase were lost, in large part, by skeletal muscle and it occurred to us that subtle in vivo changes in muscle after irradiation might have been overlooked.