The turnover of autophagic vacuoles: evaluation by quantitative electron microscopy.

Accumulation of autophagic vacuoles was induced in mouse liver, exocrine pancreas and seminal vesicle cells by intraperitoneal injection of vinblastine, leupeptin, Triton X100 or estron acetate and the turnover of the autophagic vacuole content was estimated by morphometry from the time course of regression of autophagic vacuoles following the administration of cycloheximide to the animals. The volume fractions of autophagic vacuoles increased manifold following the administration of any of the drugs in each cell type investigated. The autophagic vacuoles regressed rapidly after administration of cycloheximide to the animals pretreated with Triton X100, estron acetate and leupeptin and the decay appeared to follow first-order kinetics; the estimated half life of autophagic vacuoles was about 6-9 min. Regression of autophagic vacuoles was very slow (apparent half life 30 min or longer) in mice, pretreated with vinblastine, indicating the inhibitory action of this drug on the turnover of autophagic vacuoles in vivo.