Comparison of isoproterenol - Induced changes in lysosomal enzyme activityin vivo and in vitro

Isoproterenol was used as a drug which, when administered in high doses, is able to induce lysosomal enzyme activity changes in in vivo conditions. We correlated lysosomal enzyme activity in the absence and presence of isopro terenol, obtained in whole animals and in HeLa and HeDG2 cells in tissue cu lture. In vivo experiments: male Wistar rats (270 300 g) were treated subcu taneously with isoproterenol in various doses. Effect of isoproterenol on l ysosomal enzyme activity was assayed in the heart after differential centri fugation. In vitro experiments: Isoproterenol in concentrations 0.1-100 mu g/ml was added to HeLa and HepG2 cells and the activity of lysosomal enzyme was measured in the cell homogenate. In the sedimentable and nonsedimentab le fractions of the rat my ocardium, the isoproterenol-induced changes in t he activity of lysosomal enzyme were time-and dose-dependent. In HeLa cells . isoproterenol administration caused a dose-dependent increase of lysosoma l enzyme activity, while in HepG2 cells the activity remained unchanged. Th us the isoproterenol-induced changes in lysosomal enzyme activity in the ra t myocardium were comparable with the results found in vitro in HeLa cells.