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Publication AbstractsOrthostatic Tolerance and Hormonal Changes in Women During 120 Days of Head-Down Bed RestAlain Maillet, Ph.D., Monia Zaouali-Ajina, M.D., Ph.D., Dmitri Vorobiev, M.D., Ph.D., Stéphane Blanc, P.h.D., Lioudmila Pastouchkova, Ph.D., Gallina Reushkina, Ph.D., Boris Morukov, M.D., Anatoly I. Grigoriev, M.D., Claude Gharib M.D., Ph.D., and Guillemette Gauquelin-Koch, Ph.D.Aviat Space Environ Med 2000; 71:706-14 AbstractBackground: Women will be included as mission specialists in the upcoming International Space Station program. This paper describes the changes in volume-regulating hormones and determines the degree of degradation in orthostatic tolerance in a group of women after 120 d of bed rest. The aim of this study was to test a countermeasure program to be used by women during long-duration spaceflights. Methods: For 120 d of -6° head-down bed rest (HDBR), eight healthy women were assigned either to a no-countermeasure (No-CM, n = 4), or to a countermeasure (CM, n = 4) group. In the countermeasure group, exercise began after 2 wk, pharmacological agents were given during the 1st and 3rd mo, and the "Centaur" suit was worn on the last day of bed rest and during the day time for several days after bed rest. Diet supplements were taken during the 1st and 4th mo of HDBR. Tilt tests were run before and after HDBR. Results: After the HDBR, none of the CM subjects, had pre-syncopal or syncopal symptoms during tilt tests: BP was well maintained in the CM group, while heart rate and BP changed in the No-CM group. In plasma, atrial natriuretic peptide (ANP) increased in both groups and remained high throughout HDBR, while aldosterone increased and remained elevated in the No-CM group. Natriuresis was decreased during HDBR. Conclusion: The CM protocols used during this study were efficient and prevented orthostatic intolerance for the four CM subjects. It would be necessary to obtain more data regarding this set of CM protocols on female subjects to lead to statistical and formal conclusions.Keywords: bed rest, women, volume regulating hormones, microgravity simulation, orthostatic tolerance, countermeasures. Information on subscribing, and on obtaining copies of an article or of an entire issue. Table of Contents for Volume 71, Number 7 of the ASME journal.
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