Lactate is produced exclusively as the result of glucose metabolism as t he normal endpoint of tissue glycolysis. It is produced from pyruvate, mainly by skeletal muscle, erythrocytes, the brain, the gut, and skin, in a reaction catalyzed by lactate dehydrogenase (LDH):
The lactate produced is a dead-end product and is simply converted back to pyruvate, which is then utilized primarily by the liver (about 50 per cent) and the kidneys (about 25 per cent). Lactate is used for gluconeogenesis, or is oxidized to carbon dioxide and water via the tricarboxylic acid cycle in the mitochondria, producing adenosine triphosphate (ATP). In the presence of cellular hypoxia, the ratio of NADH to NAD increases so that the ratio of lactate to pyruvate increases (type A lactic acidosis). When glycolysis is stimulated or pyruvate metabolism is impaired by depressed activity of pyruvate dehydrogenase, the formation of both pyruvate and lactate can be increased, but the ratio of lactate to pyruvate remains normal (type B lactic acidosis).
Was this article helpful?