Cerebral cortical blood flow during loss of consciousness induced by gravitational stress in rhesus monkeys.
We investigated the influence of +Gz acceleration (head-to-foot inertial forces) onset on cerebral cortical blood flow (CBF) of rhesus monkeys to study the mechanisms underlying +Gz-induced loss of consciousness (G-LOC). CBF was measured through a chronic cranial window by laser-Doppler flowmetry and electrodes in contact with the dura mater were used to detect G-LOC (suppression of the cortical electrical activity). The animals were centrifuged up to +12 Gz with different G-onset rate until G-LOC occurred. G-LOC was preceded by a 2-5 s decrease in CBF. At G-LOC detection, CBF was not related to G-onset rate (mean CBF change: -76 +/- 9% of control value). We conclude that G-LOC results from cerebral ischemia rather than from mechanical stresses applied to the brain.
Florence
G
G
Institut de Médicine Aérospatiale du Service de Santé des Armées, Département de Physiologie Aérospatiale, BP 73, 91 223, Brétigny sur Orge, France. gflorence@imassa.fr
Bonnier
R
R
Riondet
L
L
Plagnes
D
D
Lagarde
D
D
Van Beers
P
P
Serra
A
A
Etienne
X
X
Tran
D
D
D000818:Animals; D002498:Centrifugation; D002540:Cerebral Cortex / Q000098:blood supply*; D006112:Gravitation; D017078:Laser-Doppler Flowmetry; D008253:Macaca mulatta; D012039:Regional Blood Flow; D013312:Stress, Physiological / Q000150:complications*; D014474:Unconsciousness / Q000209:etiology* / Q000503:physiopathology*