Cortisol and lysosomal stability in normal and atheromatous rats.

The effect of cortisol on lysosomal stability has been studied in rats fed atherogenic and normal diets. beta-Glucuronidase has been taken as a lysosomal marker enzyme. Cortisol did not significantly alter total lysosomal enzyme activity in the liver or aorta or the activity present in the hepatic nuclear fraction. However, the hormone significantly increased activity in the intact lysosome and decreased soluble activity. The ratio of soluble activity (released from the lysosomes) to activity present in the intact lysosome showed that hepatic lysosomal stability was significantly increased in rats on cortisol. Cortisol tends to restore the decreased stability observed in atheromatous rats back to that in normal rats. The rate of release of enzyme from hepatic and aortic lysosomes was reduced by cortisol in both normal and atheromatous rats. Activity of serum lysosomal enzyme was also significantly lower in rats receiving cortisol. Cortisol subsequently added in vitro after the animals had been fed a normal or an atherogenic diet caused a significant in vitro decrease in the amount of enzyme released from hepatic lysosomes. The in vitro release of enzyme from lysosomes in normal rat liver progressively fell with increasing concentration of cortisol form 10(-5)--10(-4) M. Further increase in concentration up to 5 X 10(-4) M did not significantly alter enzyme release. Since cortisol was administered as its hemisuccinate the effect of succinate on lysosomal stability was also studied. It stabilized lysosomes, but the effect was much less than with cortisol.