[Functional and ultrastructural lysosome changes in surviving rat liver sections as affected by blood serum...

Using surviving rat liver slices, the influence of blood serum lipoproteins on cellular lysosomes was studied. Lipoproteins were isolated by the preparative isopicnic ultracentrifugation method. Apoproteins were separated by means of delipidation of suitable lipoprotein fractions. After preincubation of liver slices in media with high density lipoproteins (HDLP), low and very low density lipoproteins (LDDLP, VLDLP), apo-HDLP and apo-VLDLP, the rise of free acid hydrolase activities was seen. The stability of lysosomes in hypotonic solutions turned out to be low, and the tendency to lysosomal aggregation increased. Typical peribiliary localization of lysosomes in the cell remained unchanged. Following preincubation of liver slices with hydrocortisone, adrenalin and VLDLP or LDLP, the rise of free lysosomal enzyme activity, greater aggregation and lysosome polymorphism and their less osmotic resistance took place. After liver slice preincubation with hormones and HDLP, besides all of these changes, the lysosomal translocation to the nuclei was seen. When apoproteins, separately or together with hormones, were added, the same type of alteration of lysosomal membranes occurred. Our results suggest an importance of lipo (apo) proteins in the control of structure and functions of cellular lysosomal apparatus.