Influence of starvation on the intra-lysosomal proteolysis in rat liver.

Starvation induced changes in the intralysosomal proteolysis in rat liver were assessed in terms of the degradation of intravenously administered [131I]-human serum albumin 30 min after injection. Fasting for five days resulted in nearly 11% increase in the endocytic uptake of the labeled protein in lysosome rich fraction. However, the rate of degradation of internalized protein measured in terms of TCA soluble products showed a distinct decline in starved animals as compared to fed controls. The observed decrease in proteolysis was reversed completely by refeeding the starved rats for 10 days. The restoration of the degradation profiles in fasted animals was also accomplished by isolating lysosomes at a post injection period of 90 min. The results indicated that the starvation induced decrease in proteolysis was a consequence of delayed fusion of lysosomes and the phagosome containing the labeled protein.