Lactate transport in rat adipocytes: identification of monocarboxylate transporter 1 (MCT1) and its modulation during streptozotocin‐induced diabetes

Abstract

We have characterised L-lactate transport in rat adipocytes and determined whether these cells express a carrier belonging to the monocarboxylate transporter family. L-Lactate was taken up by adipocytes in a time-dependent, non-saturable manner and was inhibited (by approximately 90%) by alpha-cyano-4-hydroxycinnamate. Lactate transport was stimulated by 3.7-fold upon lowering extracellular pH from 7.5 to 6.5 suggesting the presence of a lactate/proton-cotransporter. Antibodies against mono carboxylate transporter 1 (MCT1) reacted positively with plasma membranes (PM), but not with intracellular membranes, prepared from adipocytes. MCTI expression was down-regulated in PM of adipocytes from diabetic rats, which also displayed a corresponding loss (approximately 64%) in their capacity to transport lactate. The data support a role for MCT1 in lactate transport and suggest that changes in MCT1 expression are likely to have important implications for adipocyte lactate metabolism.