Intravenous thiobarbital anaesthesia for determination of liver glycogen phosphorylase activity in rats subjected to various forms of stress.

Glycogen phosphorylase activity was determined in rat livers obtained by laparotomy in thiobarbital (Inactin, PROMONTA) anaesthesia induced by injection of the drug via a polyethylene catheter into a jugular vein as described previously [Németh et al. 1983a]. Intact rats and animals exposed to open field stress without or after i.p. injection of the alpha blocker phentolamine (Regitine, CIBA; 20 mg kg-1, 90 min before stress) or the beta blocker propranolol (Inderal, ICI; 2 mg kg-1, 30 min before stress) were studied. In stressed animals a net increase of phosphorylase activity was observed. This response was abolished after alpha blockade, while after beta blockade it was potentiated. In a further series on animals subjected to the same type of anaesthesia, the activating effect of immobilization stress on phosphorylase activity was confirmed in both fed and fasted animals, the response of the latter issuing from a lower initial level but being of the same extent as in the fed rats.