Alanine biosynthesis during starvation in skeletal muscle of the spiny dogfish, <i>Squalus acanthias</i>

Abstract

Abstract The release of alanine by dogfish ( Squalus acanthias ) skeletal muscle was assayed in vivo and alanine biosynthesis was characterized in vitro. Amino acid analyses of blood drawn from dorsal aorta and caudal vein indicated that after one day of starvation only alanine was released by tail muscle in statistically significant amounts. Alanine continued to be released for the following two weeks of starvation but fell significantly after that. Pelvic‐findepressor muscles incubated in a physiological medium synthesized significant amounts of alanine. This synthesis was dependent on a source of added isoleucine (or leucine) but not glucose. Addition to the incubation medium of 3‐mercaptopicolinic acid, an inhibitor of phosphoenolpyruvate carboxykinase had no effect on alanie biosynthesis. Thus, release of alanine by dogfish skeletal muscle is similar to that in mammals, but factors regulating biosynthesis may be different in the two groups.