The variability of urine proteome and coupled biochemical blood indicators in cosmonauts with different preflight autonomic status

Abstract The purpose of this work was to reveal the intra- and inter-individual variability of the urine proteomic composition and of biochemical blood parameters in cosmonauts with different preflight autonomic status when they are back to Earth (on the 1st and 7th day after space flight). The objects of the study were 5-minute samples of electrocardiogram (ECG) at rest and urine and venous blood samples, obtained in the same timeline from twelve male cosmonauts (age 46.5±3.4 years), who performed space flights (SF) with duration 169-199 days onboard the Russian segment of the International Space Station (ISS). Two groups with different sympathetic-parasympathetic balance were identified (each consists of 6 cosmonauts) by the results of preflight heart rate variability (HRV) analysis. We have revealed in groups of cosmonauts with preflight predominance of sympathetic or parasympathetic tone the significant differences in the directionality of changes on days 1 and 7 after the SF as compared to the preflight values in three proteins (from total amount around 200): alpha-1 subunit of collagen type VI, Mucin 1, Cadherin-13. A set of biochemical parameters, unidirectionally changing with these proteins, was different in classified groups. Direct bilirubin, potassium and total calcium move unidirectionally with collagen, direct bilirubin, potassium – with mucin, and uric acid, ferrum, alpha-1, KFK, potassium - with cadherin in group with a sympathetic tone. Potassium, ferrum, alpha-1 move unidirectionally with collagen, amylase, KFK, AST, urea, inorganic phosphate, glucose, alkaline phosphatase, ionized calcium – with mucin, and total ferrum biding capacity, transferrin, glucose gamma globulin transferase - with cadherin in group with parasympathetic predominance. Probably, differences between groups in the concentration of these proteins and their different relationship with some biochemical parameters reflect different ways to achieve the same goal - adaptation to a complex of SF factors and re-adaptation after returning to Earth.