Document Detail

Effects of hypercapnia on brain pHi and phosphate metabolite regulation by 31P-NMR.
MedLine Citation:
PMID:  2501277     Owner:  NLM     Status:  MEDLINE    
The ability of brain cells to regulate intracellular pH (pHi) and several phosphate metabolites was evaluated during 1 h of hypercapnia (inspiratory CO2 fraction of 0.10 and 0.05) in anesthetized rats by 31P high-field (145.6 MHz) nuclear magnetic resonance spectroscopy. Body temperature was maintained at 37 +/- 0.5 degrees C. Fully relaxed spectra were obtained for controls and 30-50 min after CO2 loading and CO2 withdrawal. Spectra were taken serially every 2.5 min after gas mixtures were changed. Brain pHi decreased 0.10 +/- 0.02 units [7.06 +/- 0.01 (SE)] to 6.96 +/- 0.01 (P less than 0.001) after 30-50 min of 10% CO2 breathing, and arterial pH decreased 0.24 +/- 0.01 units. Brain pHi decreased by 0.045 +/- 0.01 units (7.05 +/- 0.01 to 7.01 +/- 0.01, P less than 0.05) during 5% CO2 breathing. Brain pHi returned to control values after 30-50 min of CO2 washout in both groups. In three of six animals breathing 10% CO2, there was an undershoot in brain pHi by 0.07-0.09 units between 2.5 and 20 min of hypercapnia. Three animals exhibited an overshoot in pHi by 0.06-0.11 units between 7.5 and 17.5 min during CO2 washout. Phosphocreatine-to-Pi and Pi-to-beta-ATP ratios changed during hypercapnia and returned to base line after withdrawal of CO2. The findings of a smaller brain pHi change than arterial pH change and undershoots and overshoots in pHi support the view that pHi regulation involves active processes such as transmembrane ion transport.
M Nishimura; D C Johnson; B M Hitzig; P Okunieff; H Kazemi
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  66     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1989 May 
Date Detail:
Created Date:  1989-08-25     Completed Date:  1989-08-25     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:  2181-8     Citation Subset:  IM    
Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114.
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MeSH Terms
Adenosine Triphosphate / metabolism*
Brain / metabolism*
Carbon Dioxide / blood*
Cerebrovascular Circulation
Hydrogen-Ion Concentration
Magnetic Resonance Spectroscopy / methods
Phosphates / metabolism*
Phosphocreatine / metabolism*
Rats, Inbred Strains
Reference Values
Grant Support
Reg. No./Substance:
0/Phosphates; 124-38-9/Carbon Dioxide; 56-65-5/Adenosine Triphosphate; 67-07-2/Phosphocreatine; 7723-14-0/Phosphorus

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