| Abstract: | In order to classify the receptors involved in the hyperglycaemic response to catecholamines in the mouse, the relative potency of noradrenaline, adrenaline and isoprenaline in the induction of hyperglycaemia has been tested by giving increasing doses from 10 μg/kg to 1 mg/kg of one of the amines intraperitoneally. Following catecholamine administration the maximal concentration of glucose in the blood occurred between 10 and 30 min. and amounted to about 300 mg%. The relative potency was: adrenaline > noradrenaline while isoprenaline was inactive. The antagonistic effect on adrenaline induced hyperglycaemia of the α-adrenergic blocking compounds: phenoxybenzamine HCl (dibenzyline®) and phentolamine (regitin®) and the β-adrenergic blocking compounds: 1-(isopropylamino)-3-(o-phenoxyphenoxy)-2-propanol (Ph QA 33) and propranolol were tested by giving 1 and 10 mg/kg intraperitoneally 30 min. before the administration of adrenaline. Only phentolamine at the highest dose level was capable of preventing the hyperglycaemic response to adrenaline. Phenoxybenzamine, Ph QA 33 and propranolol proved to be inactive. It is concluded that the mechanism of adrenaline induced hyperglycaemia in mice cannot be explained simply by an α- and/or β-receptor activation. |
