Glycogen changes in the liver cells of young rats following isoprenaline treatment. (Histochemical and ultrastructural investigations).

Glycogen changes were investigated by light and electron microscopy in the liver cells of newborn rats following isoprenaline (IPR) treatment either for 1 day (2 intraperitoneal injections at 12 h interval), or for 8 days (2 intraperitoneal injections daily). On the day following the interruption of both treatments glycogen depletion was observed as compared to control rats, as evaluated by PAS reaction and confirmed by higher total phosphorylase activity. During this stage electron microscopy revealed mainly alpha-particles of glycogen associated to highly dilated smooth endoplasmic reticulum (SER) after 1-day-treatment, and to mostly increased SER after prolonged treatment. In the animals submitted to prolonged IPR administration and sacrificed at later times, glycogen masses intensely PAS-positive were strongly increased, while the activity of total phosphorylase proved accordingly lower than in the rats sacrificed at earlier times. Electron microscopy examination confirmed an increased amount of glycogen (alpha- and beta-particles) differently distributed: beta-particles were more numerous in the liver of the rats sacrificed on the last day of the experiment. At this time SER didn't appear modified as compared to control rats.