Lysine, a Precursor of Carnitine in the Rat

Abstract

Abstract Rats, fed a 20% gluten diet in which lysine is the limiting amino acid, exhibited a reduction of growth, anemia, and hypoproteinemia. Carnitine concentrations in skeletal muscle and heart of such lysine-deficient rats were significantly lower than in rats supplemented with 0.8% lysine, but were higher in the liver. Following intraperitoneal administration in lysine-deficient rats, radioactivity from dl-[6-14C]lysine, but not dl-[2-14C]lysine, was significantly incorporated into carnitine in the liver and skeletal muscle. These data thus establish a role for lysine in carnitine biosynthesis in the rat. A hypothetical scheme postulating transformations of lysine to yield carnitine is considered.