Document Detail

Local cerebral blood flow in spontaneously breathing rats subjected to graded isobaric hypoxia.
MedLine Citation:
PMID:  2122629     Owner:  NLM     Status:  MEDLINE    
Local cerebral blood flow (l-CBF) was measured with an autoradiographic technique in spontaneously breathing rats exposed to air or gas mixtures of O2 and N2, giving inspired oxygen fractions (FiO2) ranging from 0.21 to 0.07. The arterial O2 tension (PaO2) changed from 10.9 +/- 0.3 (FiO2 0.21) to 3.9 kPa (FiO2 0.07) (82 +/- 2 to 29 mmHg). Hypoxia caused hyperventilation, and the arterial CO2 tension (PaCO2) fell from 5.21 +/- 0.05 kPa (FiO2 0.21) to 3.27 kPa (FiO2 0.07) (39.1 +/- 0.4 to 24.5 mmHg). The hyperventilatory response was markedly augmented when changing FiO2 from 0.13 to 0.11, causing a fall in PaCO2 of 0.75 kPa and a shift in arterial pH from 7.45 +/- 0.01 (FiO2 0.13) to 7.54 +/- 0.01 (FiO2 0.11). The l-CBF response to hypoxia was found to be biphasic for all the observed regions. At FiO2 0.13, l-CBF was measured about 75% above control but at FiO2 0.11, only 30% above control. A further reduction in FiO2 to 0.07 caused a marked increase in l-CBF, at least 240% of control; however, the applied CBF technique did not admit quantitation. These results suggest that the mechanisms controlling the cerebrovascular response to hypoxia and changes in arterial CO2 tensions are different. The results also indicate that hyperventilation might be harmful to the patient suffering from acute hypoxia.
N Dahlgren
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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:  Acta anaesthesiologica Scandinavica     Volume:  34     ISSN:  0001-5172     ISO Abbreviation:  Acta Anaesthesiol Scand     Publication Date:  1990 Aug 
Date Detail:
Created Date:  1990-12-07     Completed Date:  1990-12-07     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370270     Medline TA:  Acta Anaesthesiol Scand     Country:  DENMARK    
Other Details:
Languages:  eng     Pagination:  463-7     Citation Subset:  IM    
Laboratory for Experimental Brain Research, University Hospital, Lund, Sweden.
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MeSH Terms
Anoxia / complications,  physiopathology*
Carbon Dioxide / blood
Cerebrovascular Circulation / physiology*
Hyperventilation / etiology
Oxygen / blood
Partial Pressure
Rats, Inbred Strains
Grant Support
Reg. No./Substance:
124-38-9/Carbon Dioxide; 7782-44-7/Oxygen

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