Changes in cardiac glycogen synthase and phosphorylase activities following stimulation of beta-adrenergic receptors in rats

Following a subcutaneous injection of isoprenaline into rats (5 mg·kg−1b.w.) the cardiac glycogen stores were depleted by about 90% in less than 15 min. Complete restoration of myocardial glycogen was slow (more than 7–8 hours) despite an elevated glycogen synthase activity. A cardioselective beta-adrenergic receptor blockade (using atenolol) resulted in a complete restoration of glycogen stores in 30 min.