Studies on brain-cortex slices. Differences in the oxidation of 14C-labelled glucose and pyruvate revealed by the action of triethyltin and other toxic agents

Abstract

The rate of appearance of C14O2 from [6-C14]giucose and [3-C14]pyruvate was measured. Pyruvate is oxidized to CO2 twice as fast as glucose, although the O2 uptake is almost the same with each substrate. The presence of 30 [mu]M-2, 4-dinitrophenol increases the output of C14O2 from [6-C14]glucose 6-fold whereas the O2 uptake is not quite doubled. Similar results are obtained with 0-1[image]-potassium chloride. The stimulating action of these 2 agents on the output of C14O2 from [3-C14]pyruvate is much less than on that from [6-C14]glucose. The effects of oligomycin, ouabain and triethyltin on the respiration of control and stimulated brain-cortex slices were studied. Triethyltin (1: 3[mu]M) inhibited the oxidation of [6-C14]glucose more than 70%, but did not inhibit the oxidation of [3-C14]pyruvate. The production of lactic acid by brain-cortex slices incubated with glucose is twice as great as that with pyruvate. Lactic acid increases 2 1/2 times in the presence of either triethyltin or oligomycin when the substrate is glucose, but is no different from the control when the substrate is pyruvate. With kidney slices the production of lactic acid from glucose is very low. It is increased by oligomycin but not by triethyltin. The results are discussed in terms of the oxidation of the extramitochondrial NADH2 [nicotinamide adenine dinucleotide] produced during glycolysis.