[Clinical and experimental studies on changes in lysosomal enzyme activity in fatty livers (author's transl)]

Abstract

In order to examine a role of lysosomes in the pathogenesis of fatty livers, analysis was made on possible etiologic factors, clinical signs and symptoms as well as laboratory data of routine liver function tests in 32 subjects with fatty livers. Of 18 cases, enzyme activities of serum acid phosphatase (Acp), beta-glucuronidase (betaG) and n-acetyl-beta-glucosaminidase (nbetaG) were measured and compared with those obtained in 20 normal subjects. Subjective symptoms were observed in 75% of the cases examined, liver swelling in 56%, positive GOT, GPT and BSP retention were in 59, 75 and 68%, respectively. The activity of serum lysosomal enzymes such as Acp, betaG and nbetaG were significantly increased and their incidence was 28, 89 and 78%, respectively. In animal experiments, activities of these enzymes in both serum and liver homogenate were examined in rats with choline-deficient, ethionine-treated, and alcoholic fatty livers. Results obtained were as follows: 1) Lysosomal enzyme activity in sera and livers of choline-deficient rats showed a significant decrease in lysosome-rich fraction and a significant increase in supernatant fraction and sera. 2) The enzyme activity in ethionine-treated rats decreased significantly in lysosome-rich fraction and tended to increase in supernatant fraction. The activity of betaG in sera increased markedly. 3) In rats given ethanol for 4 weeks, the enzyme activity of sera and liver homogenates significantly increased in lysosome-rich fraction. These results indicate that the analysis of serum lysosomal enzyme activity, in the light of clinical features and laboratory data of routine liver function tests, is useful for the diagnosis of the fatty liver. A discussion is given of a possible mode of variation of lysosomal enzymes in rats with fatty livers.