2016年7月
The relationship between widespread changes in gravity and cerebral blood flow
ENVIRONMENTAL HEALTH AND PREVENTIVE MEDICINE
- ,
- ,
- ,
- ,
- 巻
- 21
- 号
- 4
- 開始ページ
- 186
- 終了ページ
- 192
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1007/s12199-016-0513-7
- 出版者・発行元
- SPRINGER
Objectives We investigated the dose-effect relationship between wide changes in gravity from 0 to 2.0 Gz (Delta 0.5 Gz) and cerebral blood flow (CBF), to test our hypothesis that CBF has a linear relationship with levels of gravity.
Subjects and methods Ten healthy seated men were exposed to 0, 0.5, 1.0, 1.5, and 2.0 Gz for 21 min, by using a tilt chair and a short-arm human centrifuge. Steady-state CBF velocity (CBFV) in the middle cerebral artery by transcranial Doppler ultrasonography, mean arterial pressure (MAP) at the heart level (MAP(Heart)), heart rate, stroke volume, cardiac output and respiratory conditions were obtained for the last 6 min at each gravity level. Then, MAP in the middle cerebral artery (MAP(MCA)), reflecting cerebral perfusion pressure, was estimated.
Results Steady-state CBFV decreased stepwise from 0.5 to 2.0 Gz. Steady-state heart rate, stroke volume, estimated MAP(MCA) and end-tidal carbon dioxide pressure (ETCO2) also changed stepwise from hypogravity to hypergravity. On the other hand, steady-state MAP(Heart) and cardiac output did not change significantly. Steady-state CBFV positively and linearly correlated with estimated MAP(MCA) and ETCO2 in most subjects.
Conclusion The present study demonstrated stepwise gravity-induced changes in steady-state CBFV from 0.5 to 2.0 Gz despite unchanged steady-state MAP(Heart). The combined effects of reduced MAP(MCA) and ETCO2 likely led to stepwise decreases in CBFV. We caution that a mild increase in gravity from 0 to 2.0 Gz reduces CBF, even if arterial blood pressure at the heart level is maintained.
Subjects and methods Ten healthy seated men were exposed to 0, 0.5, 1.0, 1.5, and 2.0 Gz for 21 min, by using a tilt chair and a short-arm human centrifuge. Steady-state CBF velocity (CBFV) in the middle cerebral artery by transcranial Doppler ultrasonography, mean arterial pressure (MAP) at the heart level (MAP(Heart)), heart rate, stroke volume, cardiac output and respiratory conditions were obtained for the last 6 min at each gravity level. Then, MAP in the middle cerebral artery (MAP(MCA)), reflecting cerebral perfusion pressure, was estimated.
Results Steady-state CBFV decreased stepwise from 0.5 to 2.0 Gz. Steady-state heart rate, stroke volume, estimated MAP(MCA) and end-tidal carbon dioxide pressure (ETCO2) also changed stepwise from hypogravity to hypergravity. On the other hand, steady-state MAP(Heart) and cardiac output did not change significantly. Steady-state CBFV positively and linearly correlated with estimated MAP(MCA) and ETCO2 in most subjects.
Conclusion The present study demonstrated stepwise gravity-induced changes in steady-state CBFV from 0.5 to 2.0 Gz despite unchanged steady-state MAP(Heart). The combined effects of reduced MAP(MCA) and ETCO2 likely led to stepwise decreases in CBFV. We caution that a mild increase in gravity from 0 to 2.0 Gz reduces CBF, even if arterial blood pressure at the heart level is maintained.
- リンク情報
- ID情報
-
- DOI : 10.1007/s12199-016-0513-7
- ISSN : 1342-078X
- eISSN : 1347-4715
- Web of Science ID : WOS:000378580000002