Microhemodynamic Adjustments and the Type of Autinomic Regulation Under Analog Long-term Isolation Conditions

This study investigates microhemodynamic and autonomic regulation changes during long-term isolation in a 366-day SIRIUS-23 experiment involving 6 healthy volunteers (2 men and 4 women, aged 25–37 years). Heart rate variability analysis and laser Doppler flowmetry were used to assess cardiovascular system responses before, during, and after isolation. Volunteers demonstrated distinct autonomic regulation patterns, dividing into two groups based on vagal tone and vascular center activity. Group 2 showed consistently higher autonomic function throughout the experiment. Microcirculation parameters revealed decreased perfusion in the forehead area for Group 1 and fluctuating dynamics for Group 2. Both groups exhibited endothelial tone reduction and altered blood flow distribution in the toe area with increased shunt flow. Prolonged isolation significantly affects microhemodynamics and autonomic regulation. Individuals with higher vagal tone demonstrated better adaptation. These findings contribute to understanding physiological responses to long-term confinement and have implications for space mission medical support.