Document Detail

Cerebral metabolic and pressure-flow responses during sustained hypoxia in awake sheep.
MedLine Citation:
PMID:  1757369     Owner:  NLM     Status:  MEDLINE    
Conscious sheep (n = 6), exposed to 3.5 h of normobaric hypoxia (arterial PO2 = 40 Torr) while allowed varying arterial PCO2, showed striking early increments of cerebral blood flow (CBF; +200-250%, by radiolabeled microspheres) and decrements of cerebral vascular resistance (CVR) in association with an early temporary elevation of cerebral O2 consumption (CMRO2; +25-60%). After 2 h, CMRO2 returned to normoxic levels, while CBF declined to a lower but still elevated level (+150%). CBF/CMRO2 increased twofold, while cerebral fractional extraction of O2 was unchanged. Mean arterial pressure was unchanged, but cerebral venous pressure rose (+11 mmHg) in a stable fashion such that cerebral perfusion pressure declined by 13%. Cerebral venous hematocrit and hemoglobin concentration were both elevated (+2.2-2.7% Hct units; +1.0-1.3 g/dl, respectively) above the corresponding arterial values between 150 and 210 min of hypoxia, suggesting venous hemoconcentration in possible association with a transcapillary fluid shift. CBF, and especially CVR, were well correlated with arterial O2 content.
J Iwamoto; D C Curran-Everett; E Krasney; J A Krasney
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  71     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1991 Oct 
Date Detail:
Created Date:  1992-02-05     Completed Date:  1992-02-05     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1447-53     Citation Subset:  IM; S    
Department of Physiology, School of Medicine and Biomedical Sciences, State University of New York, Buffalo 14214.
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MeSH Terms
Acid-Base Equilibrium / physiology
Anoxia / metabolism,  physiopathology*
Blood Gas Analysis
Blood Pressure / physiology
Brain Chemistry / physiology*
Brain Edema / physiopathology
Cerebrovascular Circulation / physiology
Hemoglobins / physiology
Hydrogen-Ion Concentration
Intracranial Pressure / physiology
Oxygen Consumption / physiology
Vascular Resistance / physiology
Grant Support
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