Conversion of dense lysosomes into light lysosomes during hepatocytic autophagy.

Incubation of isolated rat hepatocytes under conditions which support maximal autophagy (amino acid-free medium) caused a marked alteration in the density distribution of lysosomes in continuous metrizamide gradients (mean peak density reduced from 1.14 to 1.09 g/ml). The autophagic sequestration inhibitor 3-methyladenine (3MA) partially prevented the density shift, presumably by stopping the formation of light autophagosomes which otherwise fuse with dense lysosomes and thereby alter the lysosomal density.