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Effect of Hypoglycemic Encephalopathy upon Amino Acids, High‐Energy Phosphates, and pH i in the Rat Brain In Vivo: Detection by Sequential 1 H and 31 P NMR Spectroscopy
Author(s) -
Behar K. L.,
Hollander J. A.,
Petroff O. A. C.,
Hetherington H. P.,
Prichard J. W.,
Shulman R. G.
Publication year - 1985
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.1471-4159.1985.tb08723.x
Subject(s) - phosphocreatine , glutamine , in vivo , intracellular ph , nucleoside triphosphate , glutamate receptor , chemistry , alanine , medicine , amino acid , endocrinology , biochemistry , glycine , intracellular , nuclear magnetic resonance , biology , nucleotide , energy metabolism , physics , receptor , microbiology and biotechnology , gene
Metabolic alterations in amino acids, high‐energy phosphates, and intracellular pH during and after insulin hypoglycemia in the rat brain was studied in vivo by 1 H and 31 P nuclear magnetic resonance (NMR) spectroscopy. Sequential accumulations of 1 H and 31 P spectra were obtained from a double‐tuned surface coil positioned over the exposed skull of a rat while the electroencephalogram was recorded continuously. The transition to EEG silence was accompanied by rapid declines in phosphocreatine, nucleoside triphosphate, and an increase in inorganic orthophosphate in 31 P spectra. In 1 H spectra acquired during the same time interval, the resonances of glutamate and glutamine decreased in intensity while a progressive increase in aspartate was observed. Following glucose administration, glutamate and aspartate returned to control levels (recovery half‐time, 8 min); recovery of glutamine was incomplete. An increase in lactate was detected in the 1 H spectrum during recovery but it was not associated with any change in the intracellular pH as assessed in the corresponding 31 P spectrum. Phosphocreatine returned to control levels following glucose administration, in contrast to nucleoside triphosphate and inorganic orthophosphate which recovered to only 80% and 200% of their control levels, respectively. These results show that the changes in cerebral amino acids and high‐energy phosphates detected by alternating the collection of 1 H and 31 P spectra allow for a detailed assessment of the metabolic response of the hypoglycemic brain in vivo.