Influence of aminophylline or beta-adrenoceptor blockade on glucagon release by a vasoactive adenosine analogue

The glucagon-releasing activity of adenosine-5'-ethyl-carboxamide (744-96) was studied in conscious dogs pretreated either with aminophylline or with bupranolol, a beta-adrenoceptor blocking drug. The adenosine antagonist, aminophylline, inhibited both the glucagon-releasing and the blood pressure lowering effects of 744-96 (10 microgram/kg i.v.). The actions of the adenosine analogue on glucagon release and haemodynamics were not affected by bupranolol pretreatment. These results indicate that the adenosine analogue mediates glucagon release by interaction with so-called adenosine receptors. A beta-adrenoceptor mediated release secondary to 744-96-induced hypotension and baroreceptor-activation can be excluded.