Synthesis and turnover of prothrombin during experimental inflammation in rats

The response of prothrombin to inflammatory reactions was investigated in rats. Inflammation was induced by the administration of either subcutaneous turpentine or intraperitoneal endotoxin, and its effects were studied 24 h and 48 h later. Albumin and alpha 1-acute-phase globulin served as the controls. There were only insignificant changes in plasma prothrombin concentration during inflammation which contrasts sharply with a decrease in circulating albumin by approximately 25% and an increase in alpha 1-acute-phase globulin by 300-400%. These changes were paralleled by similar changes in the incorporation of [3H]lysine into these proteins during the incubation of liver slices from rats that had been pretreated with the phlogistic agents. Prothrombin catabolism, studied using 131I-prothrombin, was increased by approximately 20%; albumin turnover, studied simultaneously with 125I-albumin, was not significantly affected, though the capillary transfer rate of albumin was significantly elevated 48 h after the induction of inflammation. It is concluded that rat prothrombin is not an acute-phase protein.