[Dynamics of plasma free amino acid levels in humans during antiorthostatic hypokinesia].

The amino acid composition of plasma was investigated in 8 healthy male test subjects during 49-day head-down bed rest. The concentration of most free amino acids in plasma increased significantly. The content of urea and taurine in plasma also grew. These changes were reversible and after the termination of the bed rest experiment the levels of all components in plasma returned to normal. The findings suggest that changes in the aminogram recorded during bed rest reflect rearrangement of protein metabolism and are adaptive.