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Titolo:
Effect of acute exposure to hypergravity (G(X) vs. G(Z)) on dynamic cerebral autoregulation
Autore:
Serrador, JM; Wood, SJ; Picot, PA; Stein, F; Kassam, MS; Bondar, RL; Rupert, AH; Schlegel, TT;
Indirizzi:
Univ Western Ontario, Sch Kinesiol, Cerebral Blood Flow Res Lab, London, ON N6A 3K7, Canada Univ Western Ontario London ON Canada N6A 3K7 London, ON N6A 3K7, Canada Legacy Clin Res & Technol Ctr, Dept Neurotol Res, Portland, OR 97232 USA Legacy Clin Res & Technol Ctr Portland OR USA 97232 ortland, OR 97232 USA Ryerson Polytech Univ, Fac Engn & Appl Sci, Toronto, ON M5B 2K3, Canada Ryerson Polytech Univ Toronto ON Canada M5B 2K3 ronto, ON M5B 2K3, Canada USN, Aerosp Med Res Lab, Pensacola, FL 32508 USA USN Pensacola FL USA 32508 N, Aerosp Med Res Lab, Pensacola, FL 32508 USA NASA, Life Sci Res Labs, Lyndon B Johnson Space Ctr, Houston, TX 77058 USANASA Houston TX USA 77058 ndon B Johnson Space Ctr, Houston, TX 77058 USA
Titolo Testata:
JOURNAL OF APPLIED PHYSIOLOGY
fascicolo: 5, volume: 91, anno: 2001,
pagine: 1986 - 1994
SICI:
8750-7587(2001)91:5<1986:EOAETH>2.0.ZU;2-5
Fonte:
ISI
Lingua:
ENG
Soggetto:
SYMPATHETIC NERVOUS-SYSTEM; BLOOD-FLOW AUTOREGULATION; STELLATE GANGLION BLOCK; TRANSCRANIAL DOPPLER; SPONTANEOUS FLUCTUATIONS; ORTHOSTATIC INTOLERANCE; FREQUENCY-DOMAIN; AUTO-REGULATION; ANGIOTENSIN; PRESSURE;
Keywords:
transcranial Doppler; middle cerebral artery; hypergravity; head-up tilt; centrifugation; orthostasis; vestibular; otolith; cerebral blood flow;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
49
Recensione:
Indirizzi per estratti:
Indirizzo: Serrador, JM Harvard Univ, Sch Med, HRCA Res & Training Inst, Cardiovasc Res Lab, 1200 Ctr St, Boston, MA 02131 USA Harvard Univ 1200 Ctr St Boston MA USA 02131 on, MA 02131 USA
Citazione:
J.M. Serrador et al., "Effect of acute exposure to hypergravity (G(X) vs. G(Z)) on dynamic cerebral autoregulation", J APP PHYSL, 91(5), 2001, pp. 1986-1994

Abstract

We examined the effects of 30 min of exposure to either +3G(x) (front-to-back) or +G(z) (head-to-foot) centrifugation on cerebrovascular responses to80 degrees head-up tilt (HUT) in 14 healthy individuals. Both before and after +3 G(x) or +3 G(z) centrifugation, eye-level blood pressure (BPeye), end tidal PCO2 (PETCO2), mean cerebral flow velocity (CFV) in the middle cerebral artery (transcranial Doppler ultrasound), cerebral vascular resistance (CVR), and dynamic cerebral autoregulatory gain (GAIN) were measured withsubjects in the supine position and during subsequent 80 degrees HUT for 30 min. Mean BPeye decreased with HUT in both the G(x) (n = 7) and G(z) (n =7) groups (P< 0.001), with the decrease being greater after centrifugationonly in the G(z) group (P< 0.05). PETCO2 also decreased with HUT in both groups (P< 0.01), but the absolute level of decrease was unaffected by centrifugation. CFV decreased during HUT more significantly after centrifugationthan before centrifugation in both groups (P< 0.02). However, these greater decreases were not associated with greater increases in CVR. In the supine position after centrifugation compared with before centrifugation, GAIN increased in both groups (P< 0.05, suggesting an autoregulatory deficit), with the change being correlated to a measure of otolith function (the linearvestibulo-ocular reflex) in the G(x) group (r = 0.76, P< 0.05) but not in the G(z) group (r = 0.24, P = 0.60). However, GAIN was subsequently restored to precentrifugation levels during postcentrifugation HUT (i.e., as BPeyedecreased), suggesting that both types of centrifugation resulted in a leftward shift of the cerebral autoregulation curve. We speculate that this leftward shift may have been due to vestibular activation (especially during G(x)) or potentially to an adaptation to reduced cerebral perfusion pressure during +G(z).

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Documento generato il 24/11/20 alle ore 14:27:53