Inhibition by insulin of the physiological autophagic breakdown of cell organelles.

By using electron microscopic morphometry it was found that the fractional volume of autophagic vacuoles in the cytoplasm of liver cells decreased rapidly after administering 5 units insulin per kg body weight to otherwise untreated rats. From the decay which appears to follow first order kinetics a half-life of 9 min was found for the compartment of autophagic vacuoles. The rates of autophagic breakdown calculated were different for the different cytoplasmic components, indicating that selecting mechanisms are involved in the process of segregation which is the first step in autophagy.