Fig. 3. The effect of artificially elevated lactate concentrations (lactate clamp) on metabolic processes. Increased circulatory lactate concentrations (1) result in lactate entering the cytosol, where it then enters the mitochondrion via MCT1 (2). Within the mitochondrion, lactate is converted to pyruvate via mLDH (3), which then progresses into the tricarboxylic acid (TCA) cycle (4). However, artificially raised cytosolic lactate concentrations (5) lead to suppression in glycolysis. Therefore, a resulting increase in H⁺ and NADH occurs, and acidosis inhibits phosphofructokinase (PFK) activity (6). This suppression finally results in reduced glycolytic activation and a reduction, or sparing, of glycogenolysis.