Synthesis of hepatic glycosaminoglycans in the early stages of galactosamine hepatitis: a rapid decline of heparan sulfate is followed by elevation of chondroitin sulfate and dermatan sulfate.

Administration of a single dose of D-galactosamine to rats causes time-dependent, biphasic changes of total glycosaminoglycan synthesis in liver. A rapidly occurring inhibition is followed by a significantly enhanced (greater than 2 fold) production of 35S-labeled glycosaminoglycans in later stages of injury. Degree and duration of the inhibitory phase are dose-dependent; 50% inhibition is reached at 80 mg/kg and maximum inhibition (nearly 80%) at about 300 mg/kg body weight 2 h after injection of D-galactosamine. The hepatotoxin impairs preferentially the production of heparan sulfate, whereas that of chondroitin sulfate and dermatan sulfate is diminished only slightly and for a rather short period of time. The synthesis of the latter, however, is more stimulated than that of heparan sulfate in later stages of injury. The specific radioactivity of 35S-labeled 3'-phosphoadenosine-5'-phosphosulfate (PAPS) did not change significantly during the course of acute liver damage. Glycosaminoglycan synthesis in regenerating liver was nearly unaffected by D-galactosamine. Uridine at the dose applied partially reversed D-galactosamine-inhibited synthesis of proteoheparan sulfate. In accordance with the labeling studies the content of glucosamine-containing glycosaminoglycans in treated liver decreased, whereas that of galactosamine-containing glycosaminoglycans slightly increased, resulting in a nearly 50% reduction of the glucosamine/galactosamine ratio 5 h after administration of D-galactosamine. Ion exchange chromatographic studies of 35S-labeled specific types of glycosaminoglycans from normal and galactosamine-injured liver revealed only minor structural differences.