CEREBRAL MITOCHONDRIAL REDOX STATES DURING METABOLIC STRESS IN THE IMMATURE RAT

The brain mitochondrial NAD(+)/NADH ratio, as a reflection of the oxidation-reduction (redox) state of cellular compartment, was determined under conditions of hypoxia, anoxia, hypoxia-ischemia, complete ischemia and hypoglycemia in immature rats. NAD(+)/NADH ratios were calculated from changes in the concentrations of specific oxidative substrates and calculated intracellular pH during cerebral metabolic stress. The results suggest that the use of the acetoacetate/beta-hpdroxybutyrate substrate couple provides a more accurate prediction of the mitochondrial redox state under adverse conditions than use of the alpha-ketoglutarate/glutamate couple. It is possible that the mitochondrial oxidation seen with the latter substrate couple during cerebral metabolic stress might reflect a population of cells (neurons or glia) which art substrate-deprived relative to the rest of the brain in the setting of metabolic stress produced by oxygen deficiency.