Metabolic responses to adrenaline and muscle glycogen content in dogs treated with thyroxine.

Lipolytic, hyperglycaemic and lactacidaemic responses to 1h adrenaline infusion (0.1 microgram/kg/min) were compared in resting dogs before (control) and after prolonged thyroxine (T4) treatment. Besides, the effect of 2-week thyroxine administration on muscle glycogen content, and its changes following adrenaline infusion were examined. Prolonged T4-treatment of dogs resulted in considerable alterations of the metabolic actions of adrenaline. A marked difference between the control and T4-treated dogs was also found in the muscle glycogen content, which was significantly lower in the latter. Both in the control and T4-injected dogs adrenaline infusion caused similar depletion of the muscle glycogen store. However, in all the control animals examined supercompensation of muscle glycogen was noted 1 h following termination of adrenaline infusion, whereas T4-treated dogs were unable of incurring any significant muscle glycogen deposition.