Serum-albumin Metabolism in X-irradiated Mice with Implanted Rat Bone-marrow

Summary The kinetics of loss of 131I-labelled human-serum albumin, the rate of incorporation of glycine 1-14C into endogenous-serum albumin, and the serum-albumin concentration and pool size were studied in x-irradiated mice treated with rat bone-marrow. Comparisons were made with unirradiated mice and with x-irradiated mice protected by lead shielding over one femur or by the radiation-protective compound, S, 2-aminoethylisothiuronium bromide hydrobromide. The results indicated that, in the mice with implanted rat bone-marrow, there was an increased fractional rate of loss of endogenous-serum albumin (greater than any increase in synthesis) that led to a decrease in the serum-albumin pool. Observations of glycine 1-14C incorporation suggested increased albumin synthesis. The serum-albumin concentration was subnormal; presumably because of the decreased pool and a possible increase in the plasma volume. The increased fractional rate of loss of serum albumin was attributed to increased catabolism or leakage of protein into the gastrointestinal tract or both. It could not be ascribed to renal excretion, since no protein-bound radioactivity was detected in the urine.