Brain levels of NADH and NAD+ under hypoxic and hypoglycaemic conditions in vitro.
The effects of hypoxia and hypoglycaemia on the redox state in vitro have been studied. NADH and NAD+ were extracted simultaneously from superfused cerebral cortex slices and assayed by bioluminescence. The results show a nonsignificant increase in NADH and the redox ratio in "mild hypoxia," whereas "severe hypoxia" produced an increase of over 200% in NADH and in the NADH/NAD+ ratio. When the glucose in the incubation medium was reduced from its control value of 10 mM to 0.5 mM, significant decreases in NADH and the redox ratio to 60% of control value were observed. Further decreasing the glucose to 0.2 mM gave lower levels of NADH and the redox ratio (40% of control). The effects on the redox state of alternative substrates to glucose were also tested. Replacement of glucose by 10 mM pyruvate decreased the NADH by 77% and the NADH/NAD+ ratio by 79%. Replacement of glucose with 10 mM lactate gave decreases of 70% and 71%, respectively, whereas in the presence of 15 mM 2-deoxyglucose and 5 mM glucose, the NADH was decreased by 56% and the ratio by 50%. The results are discussed in relation to levels of creatine phosphate and ATP, as well as evoked action potentials, observed from parallel studies.
Garofalo
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Division of Biochemistry, U.M.D.S. (St. Thomas's), London, England.
Cox
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Bachelard
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D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism*; D005260:Female; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism; D006168:Guinea Pigs; D007003:Hypoglycemia / Q000378:metabolism*; D002534:Hypoxia, Brain / Q000378:metabolism*; D066298:In Vitro Techniques; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D009243:NAD / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000008:administration & dosage; D010725:Phosphocreatine / Q000378:metabolism; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid
D007773:Lactates; D011773:Pyruvates; D010725:Phosphocreatine; D009243:NAD; D019344:Lactic Acid; D019289:Pyruvic Acid; D000255:Adenosine Triphosphate; D005947:Glucose; D010100:Oxygen