HEPATIC COLLAGEN-SYNTHESIS AND DEGRADATION DURING LIVER-REGENERATION AFTER PARTIAL-HEPATECTOMY

To elucidate hepatic collagen metabolism during liver regeneration aft er partial hepatectomy, we measured collagen content, collagen synthes is, and collagen-degrading enzyme activity in the remnant livers of ra ts 3, 5, 7, and 14 days after a partial hepatectomy of 68%. Hepatic co llagen synthesis was significantly higher 3, 5, and 7 days after parti al hepatectomy than it was in sham-operated control rats, but there wa s no such difference 14 days after surgery, the maximal hepatic collag en ynthesis being observed 5 days after surgery. Although the collagen concentration in the remnant liver was similar to that in the control liver, the total collagen content of the remnant liver increased rapi dly with liver regeneration until 7 days after partial hepatectomy. He patic collagenase activity was similar to the control; however, hepati c cathepsin B and cathepsin L activity and the intracellular degradati on of newly synthesized collagen were markedly decreased 3, 5, and 7 d ays after partial hepatectomy compared with the controls. Hepatic coll agen synthesis was significantly and inversely correlated with catheps in L activity and with the intracellular degradation of newly synthesi zed collagen. These findings suggest that a combination of increased c ollagen synthesis and decreased intracellular collagen degradation con tributes to the rapid supply of collagen that is observed during the e arly phase of liver regeneration.