Site of Catabolism of Serum Albumin

Abstract

THE relative importance of the liver, kidneys and intestines for the catabolism of serum albumin has been examined in Swiss albino mice, 5–6 weeks of age. Mouse serum albumin and human serum albumin were labelled with iodine-131 as described elsewhere¹ and given to the mice intravenously, about 0.5 µc or 5–15 µgm. iodoalbumin per mouse. The biological half-lives of the radioiodinated albumins were determined by one or more of three methods: (1) the living whole mouse was counted at intervals in a crystal scintillator; (2) pooled serum was obtained by exsanguination of two or three mice at a time from a given group and the protein-bound radioactivity of the serum determined; (3) protein-bound radioactivity in the individual whole mouse of a given group was estimated after homogenization of the animal in 10 per cent trichloracetic acid. All animals were given sodium iodide in their drinking water throughout the period of an experiment. Surgical operations were performed under ether anæsthesia. In these experiments, iodinated human albumin behaved in vivo as did iodinated mouse albumin; detectable antibodies to human serum albumin were not formed during the periods of study chosen.