Mechanisms of muscle tissue adaptation in response to the influence of low-dose ionizing radiation

Abstract

Mechanisms of interaction of ionizing radiation with biological objects are a chain of successive physical and physico-chemical changes, which manifest themselves in the form of excitation, primary and secondary ionization of molecules. Biosynthesis of ATP, which is carried out by a system of oxidation-reduction enzymes localized in the inner membrane of mitochondria - the respiratory chain, belongs to the vital processes that are directly disturbed under the action of ionizing radiation. The high degree of damage to this system is due to the significant radiosensitivity of metal-containing enzymes. The purpose of the work is to study the formation of the adaptive response of muscle tissue of sexually mature rats to the influence of ionizing radiation at a dose of 0.5 Gy. It was concluded that a day after irradiation with the dose of 0.5 Gy, the content of contractile proteins in skeletal muscle decreases slightly. On the 15^th day, the content of contractile proteins began to decrease. By the 30^th day, the content of contractile proteins decreased by 22.9% for myosin, by more than 11% for actin, and by 7 and 8% for troponin and tropomyosin, respectively, compared to the values of the intact group. A similar picture is observed in the cardiac muscle. Mg²⁺,Ca²⁺-ATP-ase activity of actomyosin, starting from the 1^st day was shown to be increased in both the skeletal and cardiac muscles, reaching its peak in the cardiac muscle on the 15^th day, in contrast to the skeletal muscle, where this indicator reached its peak on the 7^th day. The authors conclude that irradiation of sexually mature animals with the dose of 0.5 Gy forms an adaptive response that is accompanied by an increase in Mg²⁺,Ca²⁺-ATP-ase activity due to the formation of a strong form of binding between F-actin and myosin, actin monomers go into the typical for actomyosin “turned on stage”, and the myosin heads acquire an ordered orientation in the muscle fiber. According to author’s idea, the data obtained indicated the benefit and reasonability of using in post-radiation dysfunctions complex pharmacological treatment drugs that are able to normalize intracellular homeostasis, eliminate probable acidic changes initiated by radiation exposure, activate the processes of intramuscle energy generation and which have protective properties in relation to the muscular system.