Effects of anoxia and depolarization on the movement of carbon atoms derived from glucose into macromolecular fractions in rat brain slices

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Abstract
Incorporation of U-14 C-glucose into macromolecules (lipid, protein and nucleic acid fractions) of rat brain cortex slices was studied in vitro under conditions of anoxia and reoxygenation. Additionally, the influence of depolarization on control and postanoxic U-14 C-glucose metabolism was investigated. Potassium-induced depolarization of the slices lowered their capacity to incorporate 14C from U-14C glucose into proteins and nucleic acids without any changes in the labeling the lipids. Fifteen and 30 minutes of anoxia depressed the rate of 14C incorporation into each of the above macromolecules. When slices after 15 minutes of anoxia were transferred to an oxygenated medium their capacity to incorporate 14C from glucose into macromolecules was partly restored compared to the control. Excess of potassium in the medium during the reoxygenation period inhibited restoration of the synthetic capacity of the slices except lipids, into which incorporation of 14C was even stimulated under depolarizing conditions. The influence of anoxia and depolarization were investigated also in different classes of lipids and proteins. 14C incorporation into SDS-extractable and residual proteins and phospholipid fraction containing phosphoinositol was closest to the control during reoxygenation which suggests the relatively highest resistance of these fractions to anoxia.