A 13C isotopomer n.m.r. method for monitoring incomplete β-oxidation of fatty acids in intact tissue

S. R. Gavva, A. J. Wiethoff, P. Zhao, C. R. Malloy, A. D. Sherry

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Abstract

An n.m.r. method is presented for monitoring the extent to which fatty acids undergo β-oxidation without release of shorter-chain intermediates. It is based upon a 13C isotopomer analysis of glutamate from tissue presented with a mixture of [2,4,6,8-13C]octanoate and [1,2,3,4-13C]octanoate. The method does not require steady-state metabolic or isotopic conditions, so it may be applied during a variety of metabolic circumstances, including perfused tissue under stress and in vivo. We have tested the method in perfused rat hearts during anoxia, a model where previous work has shown that β-oxidation of palmitate is incomplete and shorter-chain intermediates are released. Indeed, n.m.r. spectra of freeze-clamped, acid-extracted tissue show that octanoate undergoes complete β-oxidation in control normoxic rat hearts, but not in anoxic hearts. Complete β-oxidation of octanoate was observed under a number of other metabolic conditions in perfused rat hearts, including low-pressure-induced ischaemia, KCl arrest and in the presence of high concentrations of competing substrates. We also demonstrate that the technique is applicable in intact tissue by taking direct measurements in perfused rat hearts using a recently published {13C}homonuclear decoupling technique and in in vivo heart and liver removed from rats after an intravenous infusion of a mixture of [2,4,6,8-13C]octanoate and [1,2,3,4-13C]octanoate.

Original languageEnglish (US)
Pages (from-to)847-853
Number of pages7
JournalBiochemical Journal
Volume303
Issue number3
DOIs
StatePublished - Jan 1 1994

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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