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Plasma volume losses during simulated weightlessness in women

Conference · · J. Nucl. Med.; (United States)
OSTI ID:5872076
Six healthy women not using oral contraceptives underwent two 11-day intervals of complete bedrest (BR) with the BR periods separated by 4 weeks of ambulatory control. Change in plasma volume (PV) was monitored during BR to test the hypothesis that these women would show a smaller decrease in PV than PV values reported in similarly stressed men due to the water retaining effects of the female hormones. Bedrest periods were timed to coincide with opposing stages of the menstrual cycle in each woman. The menstrual cycle was divided into 4 separate stages; early follicular, ovulatory, early luteal, and late luteal phases. The percent decrease of PV showed a consistent decrease for each who began BR while in stage 1, 3 or 4 of the menstrual cycle. However, the females who began in stage 2 showed a transient attenuation in PV loss. Overall, PV changes seen in women during BR were similar to those reported for men. The water-retaining effects of menstrual hormones were evident only during the high estrogen ovulatory stage. The authors conclude the protective effects of menstrual hormones on PV losses during simulated weightless conditions appear to be only small and transient.
Research Organization:
The Johns Hopkins Medical Institutions, Baltimore, MD
OSTI ID:
5872076
Report Number(s):
CONF-850611-
Conference Information:
Journal Name: J. Nucl. Med.; (United States) Journal Volume: 26:5
Country of Publication:
United States
Language:
English