Distribution of Radioactive Carbon Administered as Carbonate in the Body and Excreta of Mature Rat.

Radioactive carbon was administered to unfasted mature rats either by intraperitoneal injection of Na2C14O3 or by implantation in the peritoneal cavity of CaC14O3. Quantitative studies were made of the relative amounts of C14 excreted in the urine, the feces, expired air and incorporated by the tissues and derived components. A significant incorporation of C14 was found in the inorganic carbonate fraction of bone and in bone protein, the dentin, and enamel of the teeth, fatty acids, glycerol, hemin, red cell protein, plasma proteins, central nervous system protein, liver and muscle glycogen, muscle protein, and in the proteins of the testes and of the thoracic and abdominal viscera.