Alterations in Albumin Metabolism after Serum and Albumin Infusions*

Abstract

The intravenous administration of whole serum or of serum albumin results in a temporary increase in the concentration of circulating protein; the rate of return toward preinfusion levels depends upon the state of protein depletion or pool size and upon the rates of synthesis and degradation of albumin (1-6). Much of the infused protein can be accounted for by increased nitrogen excretion in the urine (2-4); the remainder has been assumed to be stored in intravascular or extravascular areas (1-6). The rate of disappearance of tracer-labeled homologous and heterologous albumin from plasma has been observed to increase during the infusion of whole serum or of serum albumin (6-7). Thus, although there is an increase in protein degradation associated with at least a temporary storage of protein, observations on the changes in endogenous protein synthesis and degradation that might follow such infusions are not available. The effects of prolonged infusions of pooled homologous serum or salt-poor human serum albumin on albumin metabolism in rabbits tolerant to human albumin are reported in the present study. MethodsFemale rabbits were used in all studies and were fed a standard Rockland rabbit ration. The rabbits were kept in metabolism cages, and complete urine and stool collections were made daily. Endogenous albumin metabolism was measured with rabbit albumin labeled with I' in all studies. Lugol's solution (2 to 3 drops) was added to the animals' drinking water daily to inhibit the thyroidal uptake of I' released from degraded protein.* Submitted for publication April 22, 1964; accepted June 11, 1964. A preliminary report of this work appeared in Clin. Res. 1964, 12, 279. This investigation was supported in part by grant no. A-2489 from the U. S. Public Health Service.The procedures for separating rabbit albumin from pooled rabbit serum and labeling with I' have been described previously (8-9). Two groups of rabbits were studied. The first group of 12 rabbits received whole rabbit serum.1 After the intravenous injection of 30 to 300 uc of rabbit albumin 131 (RSA-I"'), 0.6 to 0.8 ml of heparinized blood was obtained from the ear opposite to the side of injection 6 and 10 minutes later and daily thereafter for a control period of 10 to 12 days. Daily infusions of 20 to 30 ml of pooled serums containing 530 to 935 mg of albumin (equivalent to 105 to 207 mg of albumin per kg body weight) were then started and continued for 18 to 24 days while observations on plasma, urine, and stool radioactivity were continued. At this time, and while the infusions were continued, a second injection of albumin I131 was made to remeasure albumin distribution and pool size. Plasma samples were obtained just before the serum infusion for that day.A second group of 6 rabbits, tolerant to human serum albumin, was also studied. Seventy-five to 100 ,uc of rabbit albumin I' was injected intravenously, and control values were obtained for 7 to 10 days as described above. The rabbits then received between 125 and 150 mg of human albumin per...

Factors Determining the Post-Operative Hypo-Albuminaemia in Cancer Patients-Stepwise Regression Analysis

“…Our study reveals that there is a negative correlation between the supply of IG and albuminaemia. The infusion of any colloidal solution can decrease albumin synthesis, because albumin synthesis in the liver is primarily regulated by osmoreceptors in the hepatic interstitial space (36). Our study suggests that immunoglobulin supply intensifies the acute phase negative response and, at the same time, decreases the positive reactants response.…”

Turnover of autologous? 1-antitrypsin in a patient with congenital analbuminemia

“…In the extreme situation of analbuminemia the half-life of radiolabelled albumin can be prolonged up to six times the normal value [4,8,17]; however, it returns to normal after infusion of albumin. In addition, the half-life of albumin decreases during albumin infusion into normal laboratory animals [14].…”

Albumin and gamma-globulin tracer studies in protein depletion states.

“…In a series of papers based on experimental reduction and expansion of the albumin pool size Rothschild and his colleagues (36)(37)(38)(39) concluded that the quantity of albumin degraded was related to albumin concentration or pool size. It would be of interest to know whether a fall in albumin catabolic rate is brought about by reduction of the serum albumin concentration or by contraction of either the intra-or extravascular pool.…”

“…These findings may correspond to our plasmapheresis experiments with ad libitum feeding and suggest that albumin synthesis will increase when protein is lost from the body, provided dietary nitrogen is adequate. In their series of experiments Rothschild and his colleagues (36)(37)(38)(39) concluded that synthesis of albumin was regulated by the colloidal osmotic pressure of plasma, not by the albumin concentration. This problem may not finally be answered until a direct method of measuring albumin synthesis is applied.…”