Influence of phenobarbital on glycogen metabolism of rat liver pretreated with N-nitrosomorpholine

Sprague-Dawley rats were treated with N-nitrosomorpholine. (NNM)alone (7 weeks, 120 mg/I in drinking water), with NNM followedby phenobarbital (PB) (750 mg/l for 6 weeks) or PB alone. Thelivers from these animals were investigated for glycogen contentand activities of glucose-6- phosphatase, glucose-6-phosphatedehydrogenase, glycogen phosphorylase and glycogen synthetase.The following parameters proved to be significantly alteredin the livers of rats treated with either NNM or PB or bothcompared with untreated controls: glycogen content was increasedand the activities of glucose-6-phosphalase and glycogen synthetasewere decreased. Although these data show some similarities inchanges of glycogen metabolism of livers treated with NNM orPB, earlier histochemical investigations revealed importantdifferences in the distribution of these alterations withinthe liver parenchyma.