Collagenase and collagenolytic cathepsin in normal and fibrotic rat liver

Collagenase and collagenolytic cathepsin activities in normal and carbon tetrachloride-induced fibrotic livers of rats were simultaneously determined at 35 and 25 degrees C for 18 h, using the same 14C-labeled neutral soluble collagen as a substrate. Collagenolytic cathepsin had higher activity under the assay conditions at both 35 and 25 degrees C than collagenase in normal and fibrotic livers. On sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis, the collagen was visibly degraded by collagenolytic cathepsin, but not by collagenase. These results indicate that, unlike collagenase, collagenolytic cathepsins exist as active forms in the rat liver, and can participate in the degradation of collagens, especially of soluble collagens including procollagens.