Rc. Poole et Ap. Halestrap, TRANSPORT OF LACTATE AND OTHER MONOCARBOXYLATES ACROSS MAMMALIAN PLASMA-MEMBRANES, The American journal of physiology, 264(4), 1993, pp. 761-782
Transport of L-lactate across the plasma membrane is of considerable i
mportance to almost all mammalian cells. In most cells a specific H+-m
onocarboxylate cotransporter is largely responsible for this process;
the capacity of this carrier is usually very high, to support the high
rates of production or utilization of L-lactate. The best characteriz
ed H+-monocarboxylate transporter is that of the erythrocyte membrane,
which transports L-lactate and a wide range of other aliphatic monoca
rboxylates, including pyruvate and the ketone bodies acetoacetate and
beta-hydroxybutyrate. This carrier is inhibited by alpha-cyanocinnamat
e derivatives and some stilbene disulfonates and has been identified a
s a protein of 35-50 kDa on the basis of purification and specific lab
eling experiments. Other cells possess similar alpha-cyanocinnamate-se
nsitive H+-linked monocarboxylate transporters, but in some cases ther
e are significant differences in the properties of these systems, suff
icient to suggest the existence of a family of such carriers. In parti
cular, cardiac muscle and tumor cells have transporters that differ in
their K(m) values for certain substrates (including stereoselectivity
for L- over D-lactate) and in their sensitivity to inhibitors. Mitoch
ondria, bacteria, and yeast also possess H+-monocarboxylate transporte
rs that share some properties in common with those in the mammalian pl
asma membrane but are adapted to their specific roles. However, there
are distinct Na+-monocarboxylate cotransporters on the luminal surface
of intestinal and kidney epithelia, which enable active uptake of lac
tate, pyruvate, and ketone bodies in these tissues. This article revie
ws the properties of these transport systems and their role in mammali
an metabolism.