Usefulness and limitations of head-down tilt method as a ground-based simulation for phenomena occurring in microgravity
- Paper number
IAC-05-A1.4.01
- Author
Dr. Masao Yamasaki, Dept. of Physiol., Fukushima Medical University School of Medicine, Japan
- Coauthor
Dr. Yahiro Netsu, Japan
- Coauthor
Dr. Fumihiko Yoshikawa, Japan
- Coauthor
Dr. Tsuyoshi Shimizu, Suwa Maternity Clinic, Japan
- Year
2005
- Abstract
We have investigated changes in function and structure of the cardiovascular system and its regulation mechanisms under microgravity conditions using head-down tilt and parabolic flight methods in the rabbit and rat. Concerning the head-down tilt method, it has been widely used as an analogue of the microgravitational environment for animals and the human; however the properness has been not always verified. We performed both acute and chronic head-down tilt experiments and focused on the initial changes in the blood distribution of arterial flow under acute conditions and the modulation of the aortic baroreflex system in the young animals raised under chronic conditions of head-down tilt. On the basis of the results obtained in these investigations, we hypothesized that the fiber composition of the aortic nerve, one of the afferents of the baroreflex, changes and the baroreflex sensitivities in response to increase in arterial pressure are reduced under microgravity conditions in space. We examined and verified the hypotheses by the 16 days space shuttle flight experiments. The results show that the head-down tilt method is quite useful to simulate the head-ward shift of body fluid and changes in the blood circulation system including its regulation mechanisms under microgravity conditions, although the method has considerable limitations.
- Abstract document
- Manuscript document
IAC-05-A1.4.01.pdf (🔒 authorized access only).
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