Pyruvate shuttle in muscle cells: high-affinity pyruvate transport sites insensitive to trans-lactate efflux.

The specificity of the transport mechanisms for pyruvate and lactate and their sensitivity to inhibitors were studied in L6 skeletal muscle cells. Trans- and cis-lactate effects on pyruvate transport kinetic parameters were examined. Pyruvate and lactate were transported by a multisite carrier system, i.

Relations between the stage of cell maturation and lactate transporter activities in rat neonatal muscle cells in culture.

Lactate transport was investigated in newborn rat muscle cells in culture. The aim was to study the lactate transport function at two stages of cell differentiation in culture: (i) during the proliferative phase characterized by myoblasts and myotubes (MyB/MyT2) obtained after 2-3 seedings, (ii) when myotubes (MyT1) grow old in culture after 8-9 seedings. In both developmental stages MyB/MyT2, lactate was carried following a saturable and sigmoidal velocity curve: the Hill and the Scatchard plot analyses confirmed an allosteric or multisite mechanism of lactate transport with two classes of carriers: one of low and one of high affinity i.

Lactate transport in L6 skeletal muscle cells and vesicles: allosteric or multisite mechanism and functional membrane marker of differentiation.

Membrane lactate transport was studied in skeletal muscle cells and membrane vesicles from the L6 line in relation to in vitro myogenesis. In myoblasts, lactate was transported by simple diffusion and insensitive to classical inhibitors: a positive correlation between onset of creatine kinase activity and lactate transport in differentiated myotubes was observed and could be considered to be a functional marker of cell differentiation. In myotubes, complete analysis of the velocity curves (direct coordinates, Eadie-Scatchard plots, Hill plots) gave parameters showing that lactate was carried by an allosteric or multisite system.