P-31 nuclear magnetic resonance analysis of brain: Normoxic and anoxic brain slices

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Abstract
Perchloric acid extracts were prepared from liquid-N2-frozen gerbil and guinea pig brain slices studied under one of three conditions: O2-incubated, N2-incubated or O2-incubated recovery following N2 incubation. Mole percentages of the various phosphatic components contained in the extracts were determined by phosphorus-31 nuclear magnetic resonance spectroscopy. The brain slice extract spectrum revealed a previously unreported group of brain phosphodiesters at −0.73 δ relative to 85% orthophosphoric acid Although the phosphatic profiles from O2-incubated slices fromgerbils and guinea pigs revealed only minor species variations, which differed quantitatively rather than qualitatively, species-specific differences were made readily apparent and amplified by incubating brain slices under oxygen-deficient conditions. Despite these differences which were most prevalent during the recovery phase, the overall metabolic changes described herein in response to N2-incubation were in accord with the results obtained by other analytical techniques. Inorganic orthophosphate (2.63 δ) was increased, while nucleoside (principally, adenosine) triphosphate (α-, −10.92 δ, β-, −21.45 δ, and γ-, −5.80 δ) and phosphocreatine (−3.12 δ) levels were decreased in response to N2 incubation. In addition, inosine monophosphate (3.78 δ) was increased and the levels of a partially characterized acid-labile phosphate (0.85 δ, guinea pig) were decreased upon N2 incubation. Phosphoglyceride metabolism also appeared to be altered by oxygen deprivation (gerbil). These latter findings provide additional information concerning the metabolic responses of cerebral tissue to oxygen deficient conditions.