| Cerebral circulation during mild +Gz hypergravity by short-arm human centrifug. | |
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MedLine Citation:
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PMID: 22052869 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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We examined changes in cerebral circulation in 15 healthy men during exposure to mild +Gz hypergravity (1.5 Gz, head-to-foot) using a short-arm centrifuge. Continuous arterial pressure waveform (tonometry), cerebral blood flow (CBF) velocity in the middle cerebral artery (transcranial Doppler ultrasonography), and partial pressure of end-tidal carbon dioxide (ETCO(2)) were measured in the sitting position (1 Gz) and during 21 min of exposure to mild hypergravity (1.5 Gz). Dynamic cerebral autoregulation was assessed by spectral and transfer function analysis between beat-to-beat mean arterial pressure (MAP) and mean CBF velocity (MCBFV). Steady-state MAP did not change, but MCBFV was significantly reduced with 1.5 Gz (-7%). ETCO(2) was also reduced (-12%). Variability of MAP increased significantly with 1.5 Gz in low- (53%) and high-frequency ranges (88%), but variability of MCBFV did not change in these frequency ranges, resulting in significant decreases in transfer function gain between MAP and MCBFV (gain in low-frequency range, -17%; gain in high-frequency range, -13%). In contrast, all of these indices in the very-low-frequency range were unchanged. Transfer from arterial pressure oscillations to CBF fluctuations was thus suppressed in low- and high-frequency ranges. These results suggest that steady-state global CBF was reduced, but dynamic cerebral autoregulation in low- and high-frequency ranges was improved with stabilization of CBF fluctuations despite increases in arterial pressure oscillations during mild +Gz hypergravity. We speculate that this improvement in dynamic cerebral autoregulation within these frequency ranges may have been due to compensatory effects against the reduction in steady-state global CBF. |
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Authors:
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Ken-Ichi Iwasaki; Yojiro Ogawa; Ken Aoki; Ryo Yanagida |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-11-3 |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: - ISSN: 1522-1601 ISO Abbreviation: - Publication Date: 2011 Nov |
Date Detail:
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Created Date: 2011-11-4 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1Nihon University School of Medicine. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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