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EFFECT OF HYPOTHERMIA UPON ORGANIC PHOSPHATES, GLYCOLYTIC METABOLITES, CITRIC ACID CYCLE INTERMEDIATES AND ASSOCIATED AMINO ACIDS IN RAT CEREBRAL CORTEX
Author(s) -
Hägerdal M.,
Harp J.,
Siesjö B. K.
Publication year - 1975
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.1471-4159.1975.tb03858.x
Subject(s) - citric acid cycle , glycolysis , cerebral cortex , chemistry , citric acid , hypothermia , biochemistry , glutamate receptor , amino acid , tricarboxylic acid , metabolism , biology , medicine , endocrinology , receptor
—The influence of hypothermia upon the metabolism of the brain was studied by reducing body temperature in N 2 O‐anaesthetized rats to 32, 27 or 22°C, with subsequent measurements of organic phosphates, glycolytic metabolites, citric acid cycle intermediates and associated amino acids. Hypothermia was maintained for either 1 or 2 h and the effect of anaesthesia was evaluated by maintaining unanaesthetized animals at 22°C. Hypothermia had no influence on the cerebral cortical concentrations of ATP, ADP or AMP and there was only a small increase in phosphocreatine. Since the tissue concentrations of glucose and glycogen were reduced, it is concluded that the well known resistance of the hypothermie brain to ischaemia is unrelated to increased energy stores. Hypothermia was accompanied by decreases in the tissue concentrations of fructose‐1,6‐diphosphate, dihydroxyacetone phosphate, 3‐phosphoglycerate, pyruvate, lactate, α‐ketoglutarate, succinate and malate, but not of glucose‐6‐phosphate or citrate. These results indicate that metabolic flux is retarded mainly at the phosphofructokinase and isocitrate dehydrogenase steps. The largest relative reduction was seen in α‐ketoglutarate, which was possibly secondary to accumulation of ammonia. There was no change in GABA, but a decrease in glutamate and increases in aspartate and alanine. These, changes are compatible with shifts in the aspartate and alanine aminotransferase reactions, possibly induced by the fall in α‐ketoglutarate.