Blockade of adrenaline-induced hyperglycaemia in the anaesthetized cat by continuous infusion of phentolamine and propranolol.

1 The effects of adrenoceptor blocking drugs on the metabolic responses to adrenaline infusion (1 microgram kg-1 min-1) have been studied in the anaesthetized, fasted cat. 2 Propranolol, in doses (0.25 or 1 mg/kg) which prevented completely adrenaline-induced tachycardia, reduced but did not abolish adrenaline-induced hyperglycaemia. 3 Phentolamine infusion, at a rate (15 micrograms kg-1 min-1 after a priming dose of 2.5 mg/kg) which reversed the pressor effect of adrenaline, reduced but did not abolish adrenaline-induced hyperglycaemia. 4 The continuous infusion of a combination of phentolamine (15 micrograms kg-1 min-1 after a priming dose of 2.5 mg/kg) and propranolol (5 micrograms kg-1 min-1 after a priming dose of 0.25 mg/kg) prevented completely the hyperglycaemia response to adrenaline infusion over a 6 h period. 5 The increase in blood lactate concentration produced by adrenaline was prevented completely by the combined infusion of propranolol and phentolamine but was not modified by phentolamine alone.