ACTIVITY OF ACTOMYOSIN AND MYOSIN ATPASES IN DIFFERENT TYPES OF MUSCLES OF INTACT AND IRRADIATED ANIMALS

The relevance of studying the body’s resistance to adverse environmental factors, which is significantly determined by the state of adaptive systems, is due to the widespread and ubiquitous use of ionizing radiation sources and the increasing number of associated man-made disasters. One common manifestation of adaptation is a change in motor activity, which is associated, in particular, with changes in the content of contractile proteins, muscle function, and muscle contraction. It is crucial to understand the detailed mechanisms of muscle tissue function in intact animals and animals exposed to varying doses of radiation, since in these cases, preventive and therapeutic/rehabilitative medical measures should be more lenient for muscle dysfunctions caused by ionizing radiation. The aim of this study is to investigate the effect of various radiation doses on the activity of Mg2+-, Ca2+-, K+-ATPase of actomyosin and myosin in the muscular system of intact and irradiated mature animals in order to elucidate the mechanisms of the body’s adaptation to stress. The data obtained showed that irradiation at a dose of 0.5 Gy affects the activity of all the ATPases studied, but these changes occur in different ways. For example, K+-ATPase activity in cardiac and skeletal muscles decreased starting on the first day of the experiment, gradually increasing after the 30th day. However, activity levels never reached the same levels as in uninjured animals. In addition, the activity of Mg2+-, Ca2+-ATPase of actomyosin in mature animals irradiated with a dose of 1.0 Gy in skeletal muscle increased immediately on the 1st day of irradiation without a tendency to decrease, while in the cardiac muscle an acute increase in activity was observed on the 1st day, and its decrease by the 30th day of irradiation. The article proves that irradiation with a dose of 1.0 Gy is accompanied by damage to skeletal muscle, as well as a modification of the actomyosin protein complex, which is the basic unit of muscle contraction, which leads to changes in its functional activity and is expressed in an increase in the activity of K+-ATPase of actomyosin in muscles sensitive to radiation. The data presented in the article allow the authors to conclude that the decrease in the activity of myosin Mg2+-, Ca2+ -ATPase as a result of exposure to ionizing radiation with a dose of 1.0 Gy may be caused by a disruption in the structure of its active center, since the latter is free from interaction with actin, which determines its high sensitivity to the effects of ionizing radiation.