“…Although skeletal muscle tissue appears to be one of the primary sources for La − production and clearance during exercise, La − that is not metabolized in the skeletal muscle may end up in circulation (e.g., plasma) where some of the La − can be taken up via an MCT (e.g., MCT1) into red blood cells (RBC) as an intermediate step for transportation. Interestingly, La − transportation into RBC may reduce the levels of La − and H+ in the plasma, resulting in a larger gradient from interstitial fluid to plasma, which may positively influence the rate of release of these ions from exercising muscle tissue [ 70 , 71 ]. Once La − has entered circulation, it can be transported to various tissues such as the liver, heart, inactive and active skeletal muscles, and other tissues, including the brain [ 72 ].…”