Brief exposure to -2 Gz reduces cerebral oxygenation in response to stand test.
The aim of the present experiment was to determine whether a single 30 s of exposure to -2 Gz (foot-to-head inertial forces) as orthostatic stress results in altered brain oxygenation control in response to active standing. Cerebral oxygenation (oxy-Hb), cerebral blood volume (CBV), and mean arterial blood pressure at brain level (MAPbrain) were recorded in 12 subjects in supine and then in standing position (10 min), before and after -2 Gz centrifugation. The decrease in oxy-Hb (-5 +/- 9 vs. -9 +/- 10 microM, P < 0.001) and in CBV (-2 +/- 11 vs. -4 +/- 12 microM, P < 0.05) upon standing was more important after -2 Gz centrifugation, with unchanged MAPbrain (-6 +/- 7 vs. -6 +/- 9 mmHg). These findings suggest a downward shift in the static cerebral autoregulation curve.
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Cong C D
CC
Institut de médecine aérospatiale du service de santé des armées, BP 73, 91223 Brétigny/Orge, France.
Berthelot
Muriel
M
Etienne
Xavier
X
Van Beers
Pascal
P
Dussault
Caroline
C
Jouanin
Jean-Claude
JC
D000328:Adult; D001794:Blood Pressure; D001810:Blood Volume; D001921:Brain / Q000378:metabolism*; D018470:Gravity, Altered; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007024:Hypotension, Orthostatic; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism*; D011187:Posture
D006454:Hemoglobins; D010100:Oxygen