13C-NMR study of glycerol metabolism in rabbit renal cells of proximal convoluted tubules.
Perchloric acid extracts of rabbit renal proximal convoluted tubular cells (PCT) incubated with [2-13C]glycerol and [1,3-13C]glycerol were investigated by 13C-NMR spectroscopy. These 13C-NMR spectra enabled us to determine cell metabolic pathways of glycerol in PCT cells. The main percentage of 13C-label, arising from 13C-enriched glycerol, was found in glucose, lactate, glutamine and glutamate. So far it can be concluded that glycerol is a suitable substrate for PCT cells and is involved in gluconeogenesis and glycolysis as well in the Krebs cycle intermediates. Label exchange and label enrichment in 13C-labelled glucose, arising from [2-13C]glycerol and [1,3-13C]glycerol, is explained by label scrambling through the pentose shunt and a label exchange in the triose phosphate pool. From relative enrichments it is estimated that the ratio of the pyruvate kinase flux to the gluconeogenetic flux is 0.97:1 and that the ratio of pyruvate carboxylase activity relative to pyruvate dehydrogenase activity is 2.0:1. Our results show that 13C-NMR spectroscopy, using 13C-labelled substrates, is a powerful tool for the examination of renal metabolism.
Jans
A W
AW
Max-Planck-Institut für Systemphysiologie, Dortmund, Federal Republic of Germany.
Willem
R
R
D000818:Animals; D002247:Carbon Isotopes; D004735:Energy Transfer; D005943:Gluconeogenesis; D005990:Glycerol / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000201:enzymology / Q000378:metabolism*; D007773:Lactates / Q000096:biosynthesis; D009682:Magnetic Resonance Spectroscopy; D011766:Pyruvate Carboxylase / Q000378:metabolism; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism; D011817:Rabbits
D002247:Carbon Isotopes; D007773:Lactates; D011768:Pyruvate Dehydrogenase Complex; D011766:Pyruvate Carboxylase; D005990:Glycerol