Changes in plasma albumin concentration, synthesis rate, and mRNA level during acute inflammation.

Abstract

Induction of acute inflammation in rats by the subcutaneous injection of turpentine resulted in a marked fall in the concentration of albumin in plasma. This fall, which reached a minimum of 45% of the control level at 36 h after injection of the inflammatory agent, occurred in the presence of no significant change in the concentration of total protein in plasma. It was accompanied by a corresponding decline in the relative abundance of albumin mRNA in liver, which reached a minimum of 25% of the control level at 36 h after initiation of the inflammatory response. Perfused livers from 36-h postinjection rats exhibited albumin secretion rates that were reduced to 38% of control values. In contrast, release of total secretory proteins, secretion of nonalbumin plasma proteins, and synthesis of nonexported proteins by perfused livers were elevated to 166, 266, and 117% of the control values, respectively, as a result of the inflammatory response. These results demonstrate that acute inflammation causes a relative reduction in hepatic albumin mRNA, which leads to a corresponding decrease in albumin synthesis and secretion by liver and a fall in the concentration of albumin in plasma. The concentration of total protein in plasma is maintained during acute inflammation in part by increased synthesis and secretion by liver of nonalbumin plasma proteins, e.g. the acute-phase reactants.