Metabolic and hormonal status of crewmembers in short-term spaceflights.

In order to clarify biochemical adaptation of the human body to short-term microgravity, metabolic and hormonal parameters were investigated in 20 cosmonauts who performed orbital flights of 4 to 14 d in duration. The specific feature of adaptation to this exposure is the transition to a new level of hormonal regulation with a significant increase of the content (production) of glucocorticoids, catecholamines, components of the renin-angiotensin-aldosterone system, which determines a modified activity of tissue hormones, and fluid-electrolyte homeostasis, as well as simultaneous increase of insulin secretion that diminishes the metabolic effects of glucocorticoids and catecholamines.