Alterations in Albumin Metabolism after Serum and Albumin Infusions*

Abstract

Administration of whole serum or albumin induces a temporary increase in serum protein levels, but the effects of such infusions on albumin synthesis is not known. To determine the effects of exogenous serum on endogenous albumin metabolism, pooled rabbit serum containing 11-19 g of albumin were infused into 12 rabbits over 17-23 days. Following an intravenous injection of Rabbit Albumin-I131 (RSA 1131), control observations on plasma, urine and stool radio-activity were made for 7-11 days during which serum infusions were started. A second injection of RSA I131 was made to remeasure albumin metabolism at the end of the experimental period. Following the serum infusions, the mean serum albumin level increased from 3.9 to 4.2 g/100 ml. The total exchangeable albumin pool increased 20%. There was no change in albumin distribution. Albumin degradation increased by a mean of 46% and accounted for 81% of the infused albumin. In 6 rabbits made tolerant to human serum albumin (HSA), the infusion of HSA equivalent to 2[beta] of the animals, average daily albumin synthesis was accompanied by an increase in albumin degradation which accounted for 58% of the infused albumin.