Effect of a 5'-substituted adenosine analogue (744c96) on insulin and glucagon release in isolated rat islets of Langerhans.

The effect of adenosine-5'-(N-ethylcarboxamide) (744-96), a highly vasoactive adenosine analogue, was investigated on insulin and glucagon release from isolated rat islets of Langerhans. The compound inhibited glucose-induced insulin release in a dose-dependent manner (concentration range 10(-8) to 10(-5 M). No effect of 744-96 was observed on basal or on arginine-induced glucagon release. By contrast, 744-96 (5 microgram/kg i.v.) produced a significant increase in plasma glucagon and glucose levels in normal as well as in reserpinized rats. The observed failure to promote glucagon release from isolated islets may be attributable to the isolation procedure, to a release of glucagon in vivo from non-pancreatic stores, or to a non-specific effect of 744-96 on glucagon secretion.