title: Brief exposure to -2 Gz reduces cerebral oxygenation in response to stand test.
abstract: 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.
authors.affiliation: Institut de médecine aérospatiale du service de santé des armées, BP 73, 91223 Brétigny/Orge, France.
authors.forename: Cong C D
authors.initials: CC
authors.lastname: Tran
authors.forename: Muriel
authors.initials: M
authors.lastname: Berthelot
authors.forename: Xavier
authors.initials: X
authors.lastname: Etienne
authors.forename: Pascal
authors.initials: P
authors.lastname: Van Beers
authors.forename: Caroline
authors.initials: C
authors.lastname: Dussault
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Jouanin
mesh_terms: 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
chemical_list: D006454:Hemoglobins; D010100:Oxygen