Hormonal regulation during a 60-day confinement (ESA-EXEMSI'92) in humans

EXEMSI'92 was a 60-day isolation and confinement experiment with an international crew. During this second experiment of the European Space Agency (the first one was a 28-day confinement with 6 men: ISEMSI'90), blood volume regulating hormones and water balance were studied. During ISEMSI'90, stress level was elevated as shown by specific markers and we observed some interesting results which have been already observed before, during bed-rest experiments. Thus, our conclusion was that some of the physiological effects observed during bed rest could be the consequence of the "confinement effect" and/or stress imposed to the subjects during such experiments. The aim of the present physiological study was: 1/to define the origin of the blood pressure increase seen during ISEMSI'90; 2/ to study the blood volume regulating hormones (ANP, renin, aldosterone) variations; 3/ to determine the dehydration level by measuring the total body water with the doubly labeled water (DLW) method and fluid balance in general.