Knook D L, Sleyster E C, van Noord M J
Adv Exp Med Biol. 1975;53:155-69. doi: 10.1007/978-1-4757-0731-1_12.
Intact and viable parenchymal and non-parenchymal liver cell preparations were isolated by enzyme perfusion techniques from young and old rats. The distribution of the lysosomal enzymes acid phosphatase, beta-galactosidase, cathepsin D, acid DNAse, and arylsulphatase B over parenchymal and non-parenchymal cells was determined. In addition, morphological and morphometric changes which occur in parenchymal cells with age were investigated. All lysosomal enzymes studied are present in both cell classes, but non-parenchymal cells possess much ligher activities per mg protein than do parenchymal cells. This phenomenon is most pronounced for cathepsin D with a 13-times higher specific activity in non-parenchymal cells. Electron microscopic observations demonstrated that the lysosomal activities in non-parenchymal cells can be attributed mainly to the large and numerous lysosomal structures in Kupffer cells. Parenchymal cells from old rats have higher lysosomal enzyme activities per mg protein than do hepatocytes from young rats. This observation is in agreement with the general increase with age in the cytoplasmic volume fraction occupied by lysosomal structures in parenchymal cells. In general, non-parenchymal cells show no increase in specific enzyme activities with age. The results obtained suggest an increase in the heterogeneity--in both appearance and enzyme content--of the lysosomal structures in parenchymal cells with age.
采用酶灌注技术从年轻和老年大鼠中分离出完整且有活力的实质和非实质肝细胞制剂。测定了溶酶体酶酸性磷酸酶、β-半乳糖苷酶、组织蛋白酶D、酸性脱氧核糖核酸酶和芳基硫酸酯酶B在实质和非实质细胞中的分布。此外，还研究了实质细胞随年龄发生的形态学和形态计量学变化。所研究的所有溶酶体酶在这两类细胞中均有存在，但非实质细胞每毫克蛋白质的活性比实质细胞高得多。这种现象在组织蛋白酶D中最为明显，其在非实质细胞中的比活性高13倍。电子显微镜观察表明，非实质细胞中的溶酶体活性主要归因于枯否细胞中大量且众多的溶酶体结构。老年大鼠的实质细胞每毫克蛋白质的溶酶体酶活性比年轻大鼠的肝细胞高。这一观察结果与实质细胞中溶酶体结构所占细胞质体积分数随年龄普遍增加一致。一般来说，非实质细胞的比酶活性不会随年龄增加。所得结果表明，实质细胞中溶酶体结构的异质性——在外观和酶含量方面——随年龄增加。
