Blood volume regulating hormones response during two space related simulation protocols: Four-week confinement and head-down bed-rest

• Published in: Acta astronautica 1995-04, Vol.35 (8), p.547-552
• Main Authors: Maillet, A., Gauquelin, G., Gunga, H.C., Fortrat, J.O., Kirsch, K., Guell, A., Bizollon, Ch.A., Gharib, C.
• Format: Article
• Language: English
• Subjects: Adult; Aerospace Medicine; Aldosterone - blood; Aldosterone - metabolism; Arginine Vasopressin - blood; Arginine Vasopressin - metabolism; Atrial Natriuretic Factor - blood; Atrial Natriuretic Factor - metabolism; Bed Rest; Blood Pressure - physiology; Blood Volume - physiology; Creatinine - blood; Creatinine - metabolism; Environment, Controlled; Head-Down Tilt; Heart Rate - physiology; Humans; Male; Potassium - blood; Potassium - metabolism; Potassium - urine; Renin - blood; Renin - metabolism; Rest - physiology; Sodium - blood; Sodium - metabolism; Sodium - urine; Space life sciences; Space Simulation; Stress, Psychological - metabolism; Stress, Psychological - physiopathology; Weightlessness Simulation
• ISSN: 0094-5765; 1879-2030
• DOI: 10.1016/0094-5765(95)00001-G

The volume of regulating hormones (renin, aldosterone, arginine vasopressin and atrial natriuretic factor), electrolytes and creatinine concentrations, and blood pressure were measured in two different four-week experimental protocols: respectively −6 ° head-down bed-rest (5 subjects) and confinement (6 subjects). We observed a significant increase ( P < 0.01 at D2 vs D-5) of systolic blood pressure during confinement and a different level of response for some hormones, especially for arginine vasopressin (300% increase during confinement instead of 50% during bed-rest). The renin-angiotensin-aldosterone system was enhanced during confinement and head-down bed-rest. In both conditions, we obtained a similar pattern of response for blood volume regulating hormones. During confinement, two main factors were inactivity and stress activation of the sympathetic nervous system. In the bed-rest study the response is principally due to the fluid shift and blood volume adaptation but it is not possible to exclude the role of inactivity and stress.