| Abstract: | Changes in several parameters involved in the control of metabolism were correlated with changes in glucose utilization in rat brain slices incubated under conditions which reduced glucose oxidation by 40 to 70%. The parameters included: the concentrations of ATP, ADP, AMP, and the adenylate energy charge; the cytoplasmic oxidation-reduction state (NAD+]/NADH]), determined from the pyruvate]/lactate] equilibrium; the mitochondrial oxidation-reduction state, determined from the NH4+] ]2-oxoglutarate]/glutamate] Equilibrium; the cytoplasmic and mitochondrial oxidation-reduction potentials (in volts), calculated from the respective NAD+]/ NADH] ratios using the Nernst equation; and the difference between the cytoplasmic and mitochondrial NAD+]/NADH] potentials. The conversion of 3, 4-14C] glucose to 14CO2 and of U-14C] glucose to acetylcholine and to lipids, proteins, and nucleic acids by the brain slices were also determined. The values obtained by subtracting the mitochondrial from the cytoplasmic NAD+1/NADH] potentials correlated more closely with glucose utilization than did other parameters, under the conditions studied. For the synthesis of acetylcholine, the correlation coefficient was 0.96, and for the production of 14CO2 from 3, 4-14C] glucose it was 0.82. |
