Homeostatic reactions of the human body during exposure to 105-day isolation

Biochemical studies of blood (38 parameters) in the course of a 105-day isolation and confinement experiment were performed to assess the status of organs and tissues and some aspects of metabolism in six male volunteers. The results of the study showed that isolation was accompanied by a downward trend in the content of total protein, urea, and uric acid, as well as a decrease in the content of cholesterol and its fractions, whereas the concentration of triglycerides showed a compensatory rise. Creatinine phosphokinase activity increased at the expense of the muscular isozyme. The content of other substances that indirectly characterize the state of muscle tissue??creatinine, magnesium, and serum iron??also increased. Biochemical parameters characterizing the state of the myocardium (cardiac creatinine phosphokinase isozyme, ??-hydroxybutyrate hydrogenase, and aspartate aminotransferase) remained unchanged or decreased. Changes characteristic of hypodynamia were observed. The activity of lactate dehydrogenase tended to decrease, and the activities of total and pancreatic lipase, amylase, and ??-glutamyltransferase also decreased. These changes normalized partly on day 8 of recovery. On the whole, the metabolic trends observed in the test subjects resemble the patterns observed in cosmonauts returning from spaceflights.