[Researches of autonomic regulation of blood circulation in the condition of long-term space flight].

In the article is presented five-year experience of experimentation in autonomic regulation of blood circulation onboard the International space station. The heart rate variability (HRV) analysis was the basic methodical approach in the researches. We described probabilistic approach created on the basis of HRV analysis to an estimation of risk of pathology development in the conditions of long space flight. The individual type of autonomic regulation had essential value during the analysis of results. It is shown that the type of regulation, which is inherent in every cosmonaut in the conditions of weightlessness, remains even during following flights. We obtained the new scientific data on connection of character of adaptable reaction of an organism to the space flight factors with individual type of autonomic regulation. It is shown that staying in weightlessness is connected with changeover of regulatory systems and with transition in a zone of prenosological states. Adaptable reactions in weightlessness are characterized by tension growth of regulatory systems at preservation of sufficient functional reserves. The mobilization of additional resources after returning to the Earth is required and consequently functional reserve of mechanisms of regulation decreases. Cosmonauts with vagotonic and normo-sympatotonic types of autonomic regulation appear to be the most resistant. Knowing the type of autonomic regulation we will be able to foresee possible reaction of the cosmonaut to the factors of space flight. As a result of HRV analysis during the flight of the past few months likelihood estimations were calculated and risk categories were defined. Consequently, 3 groups of risk of pathology development were distinguished. In conclusion, theoretical and applied relevance of the conducted experiments were considered.

[Seven-day dry immersion: relations between water-electrolyte and cardiovascular responses].

The paper presents the results of the experiment with 7-day dry immersion. Eight healthy men were studied before, during and after exposure. It is shown that the primary response involves hemodynamic and water-electrolyte changes. The mechanisms of cardiovascular adaptation to immersion conditions are revealed. In particular, some electrophysiological shifts in propagation of myocardial excitation are found, leading to increase in "myocardium" index, estimated by analysis of natural small oscillations in the amplitude of the PQRST complex with dispersion ECG mapping. Revealed significant reduction of functional reserves of the cardiovascular regulatory mechanisms in the process of adaptation to dry immersion is of great practical importance. The results suggest that water-electrolyte shifts induced by dry immersion are the basis and the first phase of the further changes in autonomic regulation and myocardial functional state.

[Parameters of high definition ECG and dispersion ECG mapping on the background of amlodipin and myostimulation during 7-day dry immersion].

The article presents the results of studying electrophysiological changes in the myocardium of normal human subjects during 7-day dry immersion, and modification of the reaction to immersion by amlodipin and myostimulation. The dry immersion effects on the myocardium generally include a succession of electrophysiological shifts first in the ventricles and then in the left atrium due to, probably, blood pooling in the pulmonary vessels. Myostimulation and amlodipin affect the myocardium reaction visibly suggesting involvement of numerous components of the autonomous and central nervous systems. The positive effect of the pharmaceutical--alleviation of myocardium strain--is a result of amlodipin assistance to the coronary blood flow; however, it has a side-effect on orthostatic stability. The positive action of myostimulation is associated with unloading of the right heart and reflected in changed HD ECG parameters and growth of the "myocardium" index.