When muscle protein is catabolized in muscle during a fast, what are the fates of the amino acids?
Some AA's are partially oxidized to produce energy in muscle and other tissues.
What is not used for energy in these tissues is released into the blood and travels to the liver as glutamine, alanine, and all the other amino acids. In the liver, the carbon skeletons are converted into glucose or used for energy. The nitrogen from these amino acids is incorporated into urea and excreted in the urine