Free and small peptide-bound [ 14c]hydroxyproline synthesis in vitro in ethanol-induced hepatic injury in the rat liver

Abstract

To clarify the significance of free and small peptide-bound hydroxyproline synthesis in ethanol-induced liver injury, we measured the in vitro synthesis of [ 14C]hydroxyproline in the 67% ethanol-soluble fraction in rat liver slices, together with hepatic protein-bound [ 14C]hydroxyproline synthesis. The synthesis of free and small peptide-bound [ 14C]hydroxyproline was 11.1 ± 2.0 dpm × 10 −4/ g liver/3 hr and the synthesis of protein-bound [ 14C]hydroxyproline was 10.1 ± 3.3 dpm × 10 −4/g liver/ 3 hr in control rat liver. In the ethanol-fed rat liver, the synthesis of free and small peptide-bound [ 14C]hydroxyproline significantly increased 1.5-fold and the synthesis of protein-bound [ 14C]hydroxy-proline significantly increased 1.6-fold, while the hepatic collagen content did not change. There was a significant correlation between free and small peptide-bound [ 14C]hydroxyproline synthesis and protein-bound [ 14C]hydroxyproline synthesis. These results suggest that free and small peptide-bound hydroxy-proline synthesis plays an important role in regulating the content of hepatic collagens.