| Abstract: | The origin of the lipids accumulated in liver lysosomes after administration of Triton WR-1339 was investigated. When Triton WR-1339 was injected into rats, serum triglyceride and cholesterol increased markedly. The highest content of triglyceride was observed in the second-day serum, from which very-low-density lipoprotein (VLDL) was isolated. The VLDL was administered to normal rats, then the light mitochondrial fraction of the liver at 24 h was centrifuged in a sucrose density gradient. The activities of lysosomal enzymes, acid phosphatase, N-acetyl-beta-D-glucosaminidase and acid lipase, were all shifted to less dense fractions as compared with those of normal lysosomes. 3H]Triglyceride-labeled VLDL was injected similarly, and at 12 and 24 h after the administration, the light mitochondrial fraction of the liver was fractionated by sucrose gradient centrifugation. Protein content and radioactivity in the immunoprecipitate with anti-VLDL serum at 12 h showed almost the same distribution as acid phosphatase activity. At 24 h, though acid phosphatase activity, immunoprecipitable protein content and radioactivity were all found in less dense fractions than in the case of normal lysosomes, the former two distributions were significantly different from the latter. The anti-VLDL serum reacted in Ouchterlony tests not only with Triton-induced VLDL and normal VLDL but also with the extract from low-density lysosomes. These results suggest that the lipids accumulated in low-density lysosomes following the administration of Triton WR-1339 were probably derived from the elevated serum VLDL induced by the treatment. |
