The half-lives of typical acute phase proteins in rats and beagle dogs during acute inflammation were investigated. Acute inflammation was induced by injection of turpentine oil in rats and administration of indomethacin in beagle dogs. Serum concentrations of α2-macroglobulin (α2M) and C-reactive protein (CRP) were measured by enzyme-linked immunosorbent assay and α1-acid glycoprotein (AAG) was measured by single radial immunodiffusion. Half-life was calculated as 0.693/elimination rate constant (K). The mean half-lives in the terminal elimination phase of α2M and AAG were 68.1 and 164.8 h, respectively. The half-life of AAG was significantly longer than that of α2M. Mean half-lives in the terminal elimination phase of CRP and AAG were 161.9 and 304.4 h, respectively. The half-life of AAG was significantly longer than that of CRP in beagle dogs. No significant differences in the half-life of AAG were observed between rats and beagle dogs. Furthermore, serum concentrations in the terminal elimination phase could be simulated with the K data acquired in this study.

Abstract:The aim of this study was to investigate the synthesis of α 2 -macroglobulin (α2M) in hepatopathic rats injected with turpentine oil to induce acute inflammation. Hepatopathy was induced by oral administration of acetaminophen at a dose of 1 g/kg daily for 2 weeks or a 25% solution of carbon tetrachloride (CCl 4 ) at 2 ml/kg body weight three times per week for 7 weeks. Acute inflammation was induced by intramuscular injection of turpentine oil at a dose of 1.0 ml/kg body weight. Serum concentrations of α2M were measured by enzyme-linked immunosorbent assay. Aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and total protein differed significantly between acetaminophen or CCl 4 -induced hepatopathic rats and acetaminophen control (AA-control) or CCl 4 control (CC-control) rats. Furthermore, pathological examination confirmed hepatopathy in rat livers. Peak serum concentrations and area under the time-concentration curve for α2M showed significant differences between hepatopathic rats and AA-control or CC-control rats. Thus, serum concentrations of α2M did not increase when compared with nontreated rats.

Synthesis of α2-macoglobulin (α2M) by 3-week-old juvenile rats was compared to that of mature 7- and 11-week-old rats. Serum concentrations of α2M, interleukin (IL)-6- and cytokine-induced neutrophil chemoattractant (CINC)-1 were measured by enzyme-linked immunosorbent assay. The area under the concentration vs. time curve (AUC) for α2M was significantly different among the three groups. The synthesis of α2M increased in an age-dependent manner. No significant difference was observed for the AUC of IL-6, but that of CINC-1 in 3-week-old rats was significantly lower than that in 7- or 11-week-old rats. These results suggest that synthesis of α2M was increased in mature compared to juvenile rats, possibly due to differences in liver function. The maximum concentration of CINC-1 in 3-week-old rats was observed 6 h after turpentine oil injection. The serum concentrations of IL-6 and CINC-1 increased more quickly in juvenile rats than in mature rats after inflammatory stimulation.