The role of lysosomes in exercise-induced hepatic protein loss.

Previous reports have shown that exercise causes a loss of liver protein. The purpose of the present study was to elucidate the mechanism of this exercise-induced protein loss. Exercise caused: (1) an increase in mechanical and osmotic lysosomal fragility; (2) a significant loss of hepatic water, glycogen, protein, phospholipid and RNA; (3) loss of protein from the soluble, mitochondrial and microsomal fractions: (4) loss of mitochondrial, microsomal and cytosolic, but not lysosomal, enzyme activity; (5) an increase in the number of autophagic vacuoles; (6) an increase in the lysosomal size. Taken together, these results suggest that the autophagolysosomal system is responsible for the exercise-induced hepatic protein loss.