title: Impact of 60 days of 6° head down bed rest on cardiopulmonary function, and the effects of Taikong Yangxin Prescription as a countermeasure.
abstract: OBJECTIVE
  To study the changes in cardiopulmonary function induced by mid/long-term simulated microgravity with 6° head down bed rest (HDBR), and the effects of Taikong Yangxin Prescription (, TYP) as a countermeasure.
  
  
  METHODS
  Fourteen healthy male volunteers were randomly divided into a control group and a Chinese medicine (CM) group (7 in each group) by a random digital table based on their body weight. Both groups underwent 6° HDBR for 60 days. Subjects in the CM group received daily TYP pills and subjects in the control group received daily placebo pills. Cardiac systolic and pumping functions were measured by echocardiography before HDBR; on days 20, 42, and 57 of HDBR; and on day 3 of recovery after HDBR (R+3). Cardiopulmonary functional reserve and exercise capacity were evaluated before HDBR, on day 29, and on day R+3 by exercise testing.
  
  
  RESULTS
  The heart rate (HR) increased gradually during HDBR. The HR was significantly higher on day 57 than before HDBR in the control group (P<0.05), but did not increase significantly in the CM group. The stroke volume/stroke volume index, ejection fraction, and left ventricular fractional shortening tended to decrease over time in the control group, but not in the CM group. These parameters were significantly higher in the CM group than in the control group on day 42 (P<0.05 or <0.01). Exercise testing showed that maximum O2 consumption (VO2max), metabolic equivalents, relative O2 consumption (VO2), O2 pulse, and exercise duration were significantly lower on day 29 than before HDBR in the control group, but not in the CM group.
  
  
  CONCLUSIONS
  Sixty days of 6° HDBR induced a reduction in cardiac systolic and pumping functions, and reduced cardiopulmonary functional reserve and exercise capacity. Administration of TYP significantly improved cardiac systolic and pumping functions, and maintained cardiopulmonary functional reserve and exercise capacity.
authors.affiliation: State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, 100094, China.
authors.forename: Hong-zhi
authors.initials: HZ
authors.lastname: Shi
authors.forename: Yong-zhi
authors.initials: YZ
authors.lastname: Li
authors.forename: Zhi-zhong
authors.initials: ZZ
authors.lastname: Tang
authors.forename: Chong-fa
authors.initials: CF
authors.lastname: Zhong
authors.forename: Quan-chun
authors.initials: QC
authors.lastname: Fan
authors.forename: Jian-yi
authors.initials: JY
authors.lastname: Gao
authors.forename: Jun-lian
authors.initials: JL
authors.lastname: Liu
authors.forename: Tao
authors.initials: T
authors.lastname: Mi
authors.forename: Shuang
authors.initials: S
authors.lastname: Zhao
authors.forename: Ying-hui
authors.initials: YH
authors.lastname: Li
mesh_terms: D000328:Adult; D001510:Bed Rest; D004365:Drugs, Chinese Herbal; D005080:Exercise Test; D006321:Heart / Q000502:physiology*; D006801:Humans; D008168:Lung / Q000502:physiology*; D008297:Male
chemical_list: D004365:Drugs, Chinese Herbal; C000597953:taikong yanxin