Effect on vitamin A on the development of galactosamine-induced hepatitis in rats

In order to elucidate the role of lysosomes in experimental hepatitis caused by D-galactosamine in rats the activities of cathepsin A and D and acid carboxypeptidase were measured. Enzyme activities were assayed in liver homogenate, lysosomal supernatant fraction and lysosomal sediment fraction. Lysosomal enriched fractions were prepared according to De Duve. Vitamin A in high doses aggravates the morphological alterations observed in galactosamine treated rats. At the same time the labilization of lysosomes increases substantially. This effect was induced by doses of retinyl-palmitate that normally caused only an activation of Kupffer cells and no significant liberation of lysosomal peptidehydrolases. The activities of cathepsin A and D increased 2-fold in liver homogenate after combined treatment with galactosamine and vitamin A, whereas the activity of acid carboxypeptidase decreased markedly.