STUDIES ON ALBUMIN SYNTHESIS: THE EFFECTS OF DEXTRAN AND CORTISONE ON ALBUMIN METABOLISM IN RABBITS STUDIED WITH ALBUMIN-I131*

Abstract

This report attempts to define albumin metabolism in the presence of dextran-induced hypoalbuminemia. After development of hypoalbuminemia, rates of albumin synthesis and degradation were studied and compared with control values. Cortisone acetate was then given to increase the rate of albumin degradation, and the rates of albumin synthesis were remeasured. Rabbit albumin-Il31 was employed as a tracer for endogenous albumin distribution and metabolism. Following an initial injection of albumin-I131 and a control period, dextran, 1.0 - 1.5 gm/day, was administered for 17-30 days. Albumin metabolism was remeasured with a second injection of albumin-I131 while dextran was continued. Six rabbits then received cortisone acetate, 3 mg/kg/day, for 9-17 days and the study repeated in the presence of the combined treatment. Two rabbits received dextran and cortisone simultaneously. Dextran infusions resulted in a 22.3% increase in plasma volume and decreases of 35.8% in plasma albumin concentration, 15.5% in the albumin pool, and 22.3% in albumin degradation. Thus albumin synthesis was depressed even further. Extravascular albumin fell only 10%. Cortisone treatment resulted in increases of 59.5% in plasma volume, 7.4% in albumin concentration, 38.4% in albumin pool and 92% in albumin degradation, indicating an even greater increment in albumin synthesis. Dextran levels remained essentially unaltered in the presence of the expanded plasma volume indicating a similar alteration in dextran distribution. It is postulated that the combination of extravascular albumin and dextran may have resulted in an extra-vascular colloid concentration high enough to inhibit albumin synthesis. Cortisone by mobilizing extravascular albumin and dextran may have reversed this effect and stimulated albumin synthesis.