Evidence for glucagon-releasing activity of vasoactive adenosine analogues in the conscious dog.

An investigation was carried out in conscious dogs concerning the effects of three adenosine derivatives substituted at the 5'-(744-96) or 2'-, 3'-, and 5'-positions (744-98, 744-99), with pronounced and long-lasting coronary dilator activity, on glucagon release. All three compounds (10 microgram/kg i.v.) induced a sustained increase in plasma glucose and a decrease in plasma FFA concentration; concomitantly, plasma glucagon levels rose 2--3 fold. Changes in plasma insulin concentration were relatively small and of no statistical significance. A simultaneous fall in arterial blood pressure was also observed. A lowering of blood pressure of similar magnitude by sodium nitroprusside infusion in control experiments failed to show any significant effect on plasma glucagon level. These results point to a specific effect of vasoactive adenosine derivatives on glucagon release.