Direct observation of lactate and alanine by proton double quantum spectroscopy in rat hearts supplied with [3-13C]pyruvate.
The 13C-fractional enrichments in the lactate and alanine methyl carbon positions were determined by 1H NMR spectroscopy of extracts of rat hearts perfused with various concentrations of [3-13C]pyruvate +/- unlabeled glucose or acetate. In general, the 13C-fractional enrichment of the alanine methyl carbon pool paralleled the 13C-fractional enrichment of the acetyl-CoA which entered the TCA cycle (as determined by 13C-isotopomer analysis) while the 13C-fractional enrichment of the lactate methyl carbon was always significantly lower, consistent with a pool of lactate which does not mix with exogeneous [3-13C]pyruvate. This has also been examined in intact, perfused, KCl-arrested rat hearts supplied with [3-13C]pyruvate by proton double quantum metabolite specific spectroscopy (MSS). A comparison of MSS spectra of intact hearts with one pulse spectra of extracts of those same hearts indicates there is a sizeable non-enriched pool of lactate in the intact hearts which is not visible by NMR spectroscopy.
Zhao
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P
Department of Chemistry, University of Texas at Dallas, Richardson 75083-0688.
Sherry
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AD
Malloy
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CR
Babcock
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EE
D000409:Alanine / Q000032:analysis*; D000818:Animals; D002247:Carbon Isotopes; D007773:Lactates / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D009206:Myocardium / Q000737:chemistry*; D010477:Perfusion; D011773:Pyruvates / Q000737:chemistry*; D051381:Rats; D011919:Rats, Inbred Strains
D002247:Carbon Isotopes; D007773:Lactates; D011773:Pyruvates; D000409:Alanine