title: Lactate-pyruvate interconversion in blood: implications for in vivo tracer studies.
abstract: We have evaluated lactate and pyruvate kinetics in whole blood or plasma by the addition of [1-13C]lactate (n = 5) or [1-13C]pyruvate (n = 5) and application of compartmental modeling to the resulting data. Pyruvate and lactate concentrations and tracer-to-tracee ratios were measured at frequent intervals for 45 min. Pyruvate and lactate tracer-to-tracee ratios equilibrated almost completely within 3-4 min in whole blood, whereas there was no isotopic exchange in plasma. The average rate of interconversion between unlabeled lactate and pyruvate was four to five times (pyruvate to lactate) and three to four times (lactate to pyruvate) the net production rate of lactate. We conclude that there is a very rapid interconversion between lactate and pyruvate in blood that has to be considered in the interpretation of in vivo tracer studies.
authors.affiliation: Metabolism Unit, Shriners Burns Institute, Galveston, Texas.
authors.forename: J A
authors.initials: JA
authors.lastname: Romijn
authors.forename: D L
authors.initials: DL
authors.lastname: Chinkes
authors.forename: J M
authors.initials: JM
authors.lastname: Schwarz
authors.forename: R R
authors.initials: RR
authors.lastname: Wolfe
mesh_terms: D000328:Adult; D002247:Carbon Isotopes; D006801:Humans; D007700:Kinetics; D007773:Lactates / Q000097:blood*; D019344:Lactic Acid; D008297:Male; D013058:Mass Spectrometry; D008954:Models, Biological; D009994:Osmolar Concentration; D011773:Pyruvates / Q000097:blood*; D019289:Pyruvic Acid
chemical_list: D002247:Carbon Isotopes; D007773:Lactates; D011773:Pyruvates; D019344:Lactic Acid; D019289:Pyruvic Acid