Quantitative Assessment of Blood Lactate in Shock: Measure of Hypoxia or Beneficial Energy Source

Figure 1

Schematic diagram showing the processes involved in cellular lactate biochemistry. The cellular lactate can diffuse in from the blood through the plasma membrane monocarboxylate transporters (MCT) or be produced from the reduction of pyruvate to lactate, catalyzed by the cytosolic LDH or mitochondrial mLDH. Pyruvate is produced by glycolysis of cellular glucose, which is derived from transport from the blood by the glucose transporter (GLUT) or produced from breakdown of intracellular glycogen (glycogenolysis). Pyruvate is transported into the mitochondria (MIT) via the mitochondrial pyruvate carrier (MPC) where it is oxidized to CO₂. It is hypothesized that the mitochondrial oxidative lactate processes (left side) may be spatially separated from the glycolytic processes (right side), allowing simultaneous lactate uptake and release in the same cell.