Stanishevskaya T. The regularities of thyroid regulation of physiological functionsy

The object of study: to determine the mechanisms of triiodothyronine regulation of various body functions within the range of physiological hormone concentration, at its limits and beyond them. Methods: physiological, myographic, myothermic, electrophysiological and biochemical. Theoretical and practical results, the novelty: for the first time attention has been paid to the different character of correlation in such hormonal pairs as “thyroid-stimulating hormone – thyroid hormone”: at the beginning of the concentration range of the thyroid-stimulating hormone the process of inter-hormonal regulation is realized on the basis of the positive feedback mechanism, and at the end of the scale – on the basis of the negative feedback mechanism; the area of inversion of the regulation type is located in the middle of the concentration range of the thyroid-stimulating hormone. For the first time it has been demonstrated that the regulation mechanism of the physiological functions with the help of triiodothyronine differs in quality and in quantity within the accepted normal limit of the hormone: at the beginning of the scale of the triiodothyronine physiological concentration its functional efficiency is low, and at the end of the scale it remarkably grows (from 6% to 23%). For the first time, being exemplified by 25 indices of the state of neuromuscular, cardiovascular and endocrine systems of the body were obtained experimentally-grounded evidences which proved the existence of functionally-efficient regulation of the physiological functions with the help of triiodothyronine beyond the upper limit of the common scale of the physiological hormone amplitude. There has been determined consistency in the degree of efficiency of the adrenoceptive stimulation of the skeletal muscle in various ranges of free triiodothyronine concentration. It has been demonstrated for the first time that the ability of adrenaline to stimulate (from 26% to 49 %) the level of general metabolism, chronotropic cardiac function and thermogenic cost of the external work unit (mJ) performed by the muscle, remains unchanged in the wide range of triiodothyronine concentration (3,0 – 24,0 pmol/l), and just in case the index of the hormone level is more than 25 pmol/l the ability for the adrenergic stimulation of the physiological functions is completely lost. There has been offered the conception of displaced and extended area of the functionally-useful regulation of the physiological functions with the help of triiodothyronine, which begins at the end of the physiological range of the hormone amplitude level and which extends beyond the upper limit of its accepted normal range. Scope of the work: While choosing the means and methods of correction of the hypophyseal-thyroid system functional state under the conditions of thyroid pathology, and also movement disorders and pathophysiological states of the locomotor system; in the physiology of work and sports while making prognostication of working capacity and vigor characteristics of the skeletal muscles due to the seasonal acclimatization, biorhythms, migration to other time zones, climatic zones, character of psychoemotional stress and in other cases accompanied by the activation of the hypothalamo-pituitary-thyroid system function; in the physiology of extreme states for the correction of the ergotropic characteristics of the human neuromuscular system; in higher educational institutions while studying the physiology of man and animal’s endocrine and neuromuscular systems.