Ja. Romijn et al., LACTATE-PYRUVATE INTERCONVERSION IN BLOOD - IMPLICATIONS FOR IN-VIVO TRACER STUDIES, The American journal of physiology, 266(3), 1994, pp. 50000334-50000340
We have evaluated lactate and pyruvate kinetics in whole blood or plas
ma by the addition of [1-C-13]lactate (n = 5) or [1-C-13]pyruvate (n =
5) and application of compartmental modeling to the resulting data. P
yruvate and lactate concentrations and tracer-to-tracee ratios were me
asured at frequent intervals for 45 min. Pyruvate and lactate tracer-t
o-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 fou
r to five times (pyruvate to lactate) and three to four times (lactate
to pyruvate) the net production rate of lactate. We conclude that the
re is a very rapid interconversion between lactate and pyruvate in blo
od that has to be considered in the interpretation of in vivo tracer s
tudies.