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Intracellular pH, Lactate, and Energy Metabolism in Neonatal Brain During Partial Ischemia Measured In Vivo by 31 P and 1 H Nuclear Magnetic Resonance Spectroscopy
Author(s) -
Corbett R. J. T.,
Laptook A. R.,
Nunnally R. L.,
Hassan A.,
Jackson J.
Publication year - 1988
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1988.tb01118.x
Subject(s) - intracellular ph , phosphocreatine , ischemia , acidosis , chemistry , medicine , lactic acid , in vivo , endocrinology , arterial blood , glycolysis , cerebral blood flow , venous blood , nuclear magnetic resonance , anesthesia , metabolism , intracellular , biochemistry , energy metabolism , biology , physics , microbiology and biotechnology , bacteria , genetics
Sequential 31 P and 1 H nuclear magnetic resonance spectra were measured for neonatal piglets (n = 7) to determine the relationship between brain intracellular pH (pH i ), lactate, and phosphorylated energy metabolites during partial ischemia. Simultaneous determinations of arterial and cerebral venous blood gases, pH, O 2 content, and plasma concentrations of glucose and lactate were also made. Ischemia, induced by bilateral carotid artery ligation plus hemorrhagic hypotension for 35 min, resulted in variable reductions in ATP, phosphocreatine, and increases in P i , H + , and lactate relative to control levels. In four piglets, whose arterial blood glucose rose above control, brain lactate exceeded 20 μmol g −1 with corresponding decreases in pH i of >0.7 units compared to control levels. The extents of brain acidosis and lactosis showed a strong linear correlation with each other ( r = 0.94). Maximal changes in brain lactate, pH i , and ATP at the end of ischemia showed significant positive linear correlations with the control levels of arterial blood glucose, but did not correlate with arterial glucose or arterial cerebral‐venous glucose difference values during ischemia. The relationship between pH i and buffer base deficit was comparable to results reported for adult animals up to 20 μmol ml −1 . However, in contrast to models proposed for adult brain, the continued linear relationship between pH and higher buffer base levels is most consistent with a theoretical model that assumes the presence of weak acid buffers with p K a values from 6.7 to 5.2.