Origin and Possible Significance of Alanine Production by Skeletal Muscle

摘要: Abstract These experiments were undertaken to determine the source of alanine released by skeletal muscle and clarify possible relationships between this process degradation branched chain amino acids, release glutamine, protein turnover in tissue. During incubation vitro, rat diaphragm underwent net breakdown acids into medium at a linear rate. The larger amounts glutamine lower leucine, isoleucine, valine than would be expected from average composition protein. Addition increased production alanine, glutamate, lysine, but not concentration-dependent manner. At same time, inhibited breakdown; therefore lysine must have resulted de novo synthesis or reduced catabolism these acids. All other together failed increase glutamate. Alanine appears related rapid oxidation In diaphragms fasted rats, both processes occurred rates. Amino groups on could account for all nitrogen recovered alanine. rats upon addition glucose even further when insulin was present. incorporated 14C [U-14C]glucose [14C]alanine [14C]glucose. Therefore, does reflect instead synthesized primarily exogenous findings suggest existence acid-alanine cycle organism. fasting, enhanced provide energy muscle, while concomitant serve shuttle ammonia gluconeogenic precursors back liver.