[Lipid peroxidation in tissues of rats exposed to head-down tilt, exercise or immobilization stress].

Lipid peroxidation in tissues of rats exposed to antiorthostatic hypokinesia (-15 degrees) for 60 days, heavy-load exercise (swimming) and 2-hour immobilization was investigated polarographically. Antiorthostatic hypokinesia produced activation of free-radical lipid peroxidation in skeletal muscles, myocardium and plasma which reached a peak on hypokinesia day 3 and remained elevated by day 60. Exercise and immobilization applied during hypokinesia led to an accumulation of endogenous lipid peroxidation products in skeletal muscles and in the heart, although in a lesser degree. It is postulated that during hypokinesia lipid peroxidation is most probably activated due to the following factors: increased activity of the hormonal component of the sympathicoadrenal system, accumulation of excessive quantities of free fatty acids, and reduced activity of anti-oxidant enzymes.