Lactate transport through the blood-retinal and the blood-brain barrier in rats

The retinal and brain uptake index method was utilized in a study on rats to evaluate the existence of transport systems for lactate in the blood-retinal and the blood-brain barrier, respectively. For both retina and brain a saturable, pH-dependent uptake of L-lactate was observed. The uptake could also be inhibited by pyruvate and 3-hydroxybutyrate. It is concluded that lactate is transported through the blood-retinal and the blood-brain barriers by similar carrier-mediated transport systems with affinity also to other monocarboxylic acids, such as pyruvate, and to the ketone body 3-hydroxybutyrate. The pH-dependence of the lactate transport suggests that co-transport of H+ ions or counter-transport of OH- ions takes place.