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The purpose of the study was to investigate the regulatory and metabolic changes in the circulatory system when simulating microgravity conditions in a five-day dry immersion. These changes reflect the adaptation processes characteristic for the initial stages of a space flight or a short-duration space flight. Studies were conducted with 13 healthy male volunteers aged 21 to 29 years. The assessment of regulatory and metabolic processes in the circulatory system was based on the heart rate variability (HRV) and urine proteomic profile analysis. It was found that the restructuring of hemodynamics during 5 days hypogravity begins with the inclusion of the nervous circuit of regulation, and for manifestations at the body fluids protein composition level and activation of the metabolic regulation, these periods are apparently insufficient. Perhaps this is due to the fact that the metabolic regulation, being evolutionarily ancient and genetically determined, is more stable and requires more time for its pronounced activation when stimulated by extreme life conditions. [ABSTRACT FROM AUTHOR]

The effect of the rapid redistribution of blood during head-up tilt tests in 21-day Dry Immersion suddenly became relevant in connection with the occurrence of mild hemorrhagic syndrome in the study participants. It became necessary to analyze the processes of occurrence of hemorrhagic syndrome as orthostatic and congestive purpura. The aim of this work was to study the features of the proteomic response of the human body to the rapid redistribution of blood during head-up tilt tests during 21-day immersion, which led to stagnant and orthostatic purpura. According to the results of examination of 10 healthy male volunteers aged 23–34 years after head-up tilt tests, pitting edema and local petechial hemorrhages in the soft tissues of the legs and feet were observed. Proteomic analysis of the samples was carried out by high performance liquid chromatography with tandem mass spectrometry. For bioinformatic analysis, the software packages Perseus, ANDSystem were used. From reliably different (p-value <0.05) proteins, proteins directly related to injury and changes in vascular permeability were determined. Сhanges in the levels of plasminogen, fibronectin, other factors of coagulation and fibrinolysis, activation of the complement system, changes in the coagulation cascade and concentrations of plasminogen and its activators (kallikrein, etc.), increased content of fibrinolysis products were revealed. A panel of proteins indicating changes in plasmin-antiplasmin, fibrinogen-soluble fibrin-monomeric complexes and other systems is identified. The obtained data are of scientific and practical interest in the direction of stratification of the risk of secondary hemosiderosis and evaluation of new treatment methods aimed at reducing reperfusion damage to soft tissues and parenchymal organs. • 21-day Dry Immersion led to stagnant and orthostatic purpura. • Сhanges in proteins associated with the processes of vascular damage were revealed. • Immersion affected the coagulation, fibrinolysis and complement system. [ABSTRACT FROM AUTHOR]

Keywords: proteomics; dried blood spots; dry immersion; timsTOF pro mass spectrometry; red blood cells EN proteomics dried blood spots dry immersion timsTOF pro mass spectrometry red blood cells 1 7 7 01/17/22 20220111 NES 220111 Introduction Dry immersion (DI) is one of the most widely used terrestrial microgravity models. The approach allowed us to perform deep DBS proteome analysis and to identify ~500-700 proteins in each sample with relative concentrations of each protein. Analysis of human blood and urine proteome is challenging because almost all proteins synthesized in the human body get into the plasma and the dynamic range of proteins concentrations is quite large. [Extracted from the article]