Gluconeogenesis is the process by which glucose and glycogen are synthesized in the animal body from noncarbohydrate precursors. The liver and the kidney are the two organs which carry out gluconeogenesis and gluconeogenic substrates include lactate, pyruvate, glycerol, and the glucogenic amino acids. Although all the natural amino acids except leucine and lysine are potentially glucogenic by virtue of the fact that they yield pyruvate, oxalacetate, aketoglutarate, succinyl-CoA, or fumarate during their catabolism, studies in the perfused liver indicate that only alanine, serine, proline, threonine, glutamine, asparagine, glutamate, aspartate, and arginine yield significant amounts of carbohydrate (Ross, Hems, and Krebs, 1967).