The catalytic activities of 4
glycosidases (hyaluronate-4-glycanohydrolase (EC 3.2.1.35), beta-N-acetyl-D-
glucosaminidase (EC 3.2.1.30),
beta-glucuronidase (EC 3.2.1.31),
alpha-L-iduronidase (EC 3.2.1.76)), of the
arylsulphatases A and B (EC 3.1.6.1) and of the
protease cathepsin D (EC 3.4.23.5) were measured in extracts from hepatocytes and non-parenchymal cells and in serum during the development of
thioacetamide-induced rat
liver fibrosis (22 weeks). In non-parenchymal liver cells the catalytic activities of beta-N-acetyl-D-
glucosaminidase,
beta-glucuronidase,
alpha-L-iduronidase and
cathepsin D were increased significantly during chronic liver damage, but that of hyaluronate-4-glycanohydrolase was reduced by 40 to 65% during the period of application of
thioacetamide. The catalytic activities of the
arylsulphatases were lowered by 65% compared to control values in the 12th week but with advancing liver damage the catalytic activities returned to nearly normal values. Parenchymal cells of rats, which had been liver-damaged for 6 months, contained strongly elevated activities of
beta-glucuronidase, beta-N-acetyl-D-
glucosaminidase,
arylsulphatases A and B, and
cathepsin D but only slightly increased activities of hyaluronate-4-glycanohydrolase and
alpha-L-iduronidase, respectively. In the serum of liver-damaged rats the activity of
alpha-L-iduronidase was strongly elevated, while that of
N-acetyl-beta-D-glucosaminidase was only slightly increased. The activities of
beta-glucuronidase and of
arylsulphatases A and B were decreased during the whole period of treatment. The catalytic functions of hyaluronate-4-glycanohydrolase and of
cathepsin D, respectively, were decreased initially, but both
enzyme activities were elevated during the more advanced stages of long term
thioacetamide treatment.