Laberee, K. & Milligan, C.L. (1999). Lactate transport across sarcolemmal vesicles isolated from rainbow trout white muscle. J. Exp. Biol. 202:1100-1109
Rainbow trout (Oncorhynchus mykiss) retain the majority
of lactate produced during exhaustive exercise within the white
muscle. Previous studies have suggested that this retention is
partially via a re-uptake of released lactate. The purpose of
this work was to study lactate uptake using trout white muscle
sarcolemmal vesicles. Lactate uptake in trout white muscle is
partially through a low-affinity, high capacity carrier (apparent
Km = 55 mmol l-1 and Vmax = 44.5 nmol min-1 . mg protein-1). At
high concentrations, (20 and 50 mmol l-1) pyruvate partially (37%)
inhibited lactate uptake, suggesting involvement of a monocarboxylate
carrier. The anion transport inhibitor, 4-acetoamido-4'-isothiocyanstilbene-2,2'-disulphonic
acid (SITS) and the monocarboxylate transport inhibitor a-cyano-4-hydroxycinnamate
(CHC), stimulated apparent lactate uptake. The model developed
suggests that lactate is taken up by the vesicles, at least in
part by a pyruvate-sensitive monocarboxylate carrier, and its
subsequent efflux is inhibited by SITS and CHC, suggesting that
lactate export from trout white muscle is also carrier mediated.