Metabolism of prealbumin in rats and changes induced by acute inflammation

Prealbumin was purified from rat plasma by chromatography on Blue Sepharose CL-6B, followed by chromatography on concanavalin-A--Sepharose and preparative electrophoresis in polyacrylamide gel. The overall recovery was 20%. The purified prealbumin was homogeneous upon electrophoresis in detergent containing polyacrylamide gel and was used to raise a monospecific anti-serum in rabbits. During perfusion of rat liver, [14C]-leucine was incorporated into prealbumin secreted into the perfusion medium, suggesting that the liver was synthesizing prealbumin. The ratio of the rate of incorporation of leucine into prealbumin to that into total protein was 1.5%. 125I-prealbumin had a half-life of 29 h in the bloodstream of healthy Buffalo rats on a diet containing 20% protein. Whole body homogenates from healthy rats contained 6.2 mg prealbumin/100 g body weight. The rate of synthesis of prealbumin, calculated from half-life and total body pool, was 3.6 mg prealbumin X (100 g body weight)-1 X day-1. Two days after induction of inflammation by a subcutaneous injection of turpentine, both the concentration of prealbumin in the plasma and the amount of prealbumin in the whole body homogenates decreased to a minimum of about one third of normal. The relative rate of degradation of 125I-prealbumin did not change during inflammation. The rate of synthesis of prealbumin decreased considerably, or even ceased, during acute inflammation.