The sarcolemmal lactate transporter: transmembrane determinants of lactate flux.

Lactic acid is produced and consumed under various metabolic and pathogenic conditions in numerous cell types of mammalian tissues. The movement of lactic acid and lactate anions within and between tissues depends, ultimately, on flux rates between intracellular and extracellular compartments. Flux rates themselves are dependent on several variables, including (but not limited to) exchange surface area, flow through the tissues of interest, lactate and proton concentration gradients across the cell membranes, and proton concentration gradients across the cell membranes, and permeability of the membranes to these ions. This review focuses on the selective permeability characteristics of the principal cells of lactate metabolism: skeletal muscle, heart, liver, kidney, and erythrocytes. Special attention will be paid to lactate uptake and release in skeletal muscle, the premier tissue of lactate production and consumption, and the regulator of whole body lactate dynamics during exercise and recovery from exercise.