title: Effect of epinephrine infusions imitating plasma epinephrine levels in immobilization stress and of fasting on the activity of key enzymes of liver glycogen metabolism.
abstract: In adult male rats anaesthetized with pentobarbital, intravenous infusion of 0.25 microgram kg-1 min-1 of epinephrine increased plasma epinephrine levels to more than 10 pmol ml-1 within 5 min, the values remaining constant during the next 20 min. On the other hand, a maximal increase of liver phosphorylase a was found after 5 min and this response was attenuated at 10 and 20 minutes in the fed rats. Fasting for 24 h extinguished the greatest part of this response. During infusion, a decrease of liver synthase a activity was observed in the fasted and of total synthase activity in both the fed and fasted animals. In fed rats an i.v. bolus of 0.50 microgram.kg-1 or doubling of the infusion rate for 5 min, both immediately after 20 min of infusion, led to maximal phosphorylase a activity again and to a decrease of synthase a activity. The levels of cAMP in the liver were increased by the infusion in one series and unchanged in another.
mesh_terms: D000818:Animals; D004837:Epinephrine / Q000097:blood / Q000494:pharmacology*; D005215:Fasting; D006006:Glycogen Synthase / Q000378:metabolism; D007103:Immobilization; D007262:Infusions, Intravenous; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008112:Liver Glycogen / Q000378:metabolism*; D008297:Male; D006005:Phosphorylases / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013312:Stress, Physiological / Q000378:metabolism
chemical_list: D008112:Liver Glycogen; D006005:Phosphorylases; D006006:Glycogen Synthase; D004837:Epinephrine