Control of Concentration Gradients of Pyruvate and Lactate Across Cell Membranes in Blood

The relationships of extracellular and intracellular concentrations of pyruvate and lactate ions were investigated using fresh human blood cells. Oxygen, CO2 and ph were constant within narrow limits because arterial blood was used, collected at '6° to '10°C and denatured in less than 3 minutes. Plasma values were derivable from whole blood concentrations by multiplying by 1.21 and 1.07, respectively, for pyruvate and lactate (per liter of plasma or blood water). Plasma/cell ratios were 2.30 and 1.37. These factors were the same at all levels of blood pyruvate and lactate during rest and exercise, fever, hyperventilation and thiamine deficiency. The values of cell membrane gradients and their behavior during completely in vivo experiments suggested that lactate moved passively, and freely, across the membrane, while the pyruvate gradient resulted from metabolic activity of the cells plus passive diffusion through a membrane of relatively high resistance. Submitted on February 6, 1956