Effects of ethanol on alanine metabolism in perfused mouse liver studied by 13C NMR.
- 1 October 1979
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 76 (10), 4808-4812
- https://doi.org/10.1073/pnas.76.10.4808
Abstract
Time courses of 13C labeling from alanine and ethanol in perfused mouse livers have been followed by NMR. The enrichment at specific carbons of glucose, glutamate, glutamine, aspartate, acetate, acetoacetate, beta-hydroxybutyrate, and lactate has been measured. The specific labeling of glutamate in the presence of labeled alanine and labeled or unlabeled ethanol shows that, under these conditions, alanine enters the tricarboxylic acid cycle almost exclusively through pyruvate carboxylation, whereas ethanol is the exclusive source of acetyl-CoA. In the absence of ethanol, the alanine label flows through both paths. By comparing the scrambling of 13C between C3 and C2 of glutamate it is possible to estimate the mitochondrial fumarase activity; the C6-to-C5 ratios in glucose give the additional scrambling by cytosolic fumarase activity. In addition, the C6-to-C1 and C5-to-C2 ratios in glucose show that there is about 15% flux through the pentose cycle. Finally, the C4-to-C2 ratios in glutamine and glutamate are unequal at any time (the glutamine labels reflect the label distribution in glutamate measured 1 hr earlier), providing a method for studying flow through glutamine synthetase in situ.This publication has 15 references indexed in Scilit:
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