Arginine, Glutamate, and Proline as Substrates for Oxidation and for Glycogenesis in Cephalopod Tissues

Abstract

In addition to the usual metabolic roles for arginine and proline in cephalopod metabolism (the first serving in anaerobic metabolism and the second in augmenting the Krebs cycle pool of intermediates), we found that arginine and proline were vigorously oxidized and that their catabolism appeared to proceed through two common intermediates, glutamate and ornithine. In addition, we found that glutamate and proline were both capable of supplying precursors for the gluconeogenic pathway. On a unit mass basis, highest rates of 14C-glutamate and 14C-proline incorporation into glycogen occurred in the kidney, but when overall organ and tissue mass were considered, muscle, kidney, and gill displayed comparable rates of glycogen formation from these amino acids. The possibility was considered that these interactions between arginine, proline, and glycogen metabolism may be utilized during replenishment of all three substrate stores during recovery from exhaustive exercise.