Hepatic lysosomal cathepsin activities after acute ethanol administration.

In order to determine whether acute ethanol administration produces alterations in hepatic lysosomal protease activities, male Sprague-Dawley rats were given either ethanol or isocaloric glucose by gastric intubation and the free and total activities of cathepsins B, D, H and L were measured. Twelve hours after administration, the free (nonlatent) activities of cathepsins D and H were higher in ethanol-fed rats than in glucose-fed controls, indicating a slightly higher lysosomal fragility which probably resulted from a nutritional deficiency which was evident in ethanol-fed animals. Measurement of the total (latent plus nonlatent) activities of these cathepsins in detergent-treated homogenates revealed that only cathepsin H activity in ethanol-fed rats was higher than in controls. The results indicate that acute ethanol consumption causes little or no change in the total activities of the cathepsins examined. Thus previously-reported alterations in hepatic protein catabolism following ethanol administration are not related to changes in the activities of these lysosomal proteases.