The effects of NECA (adenosine-5'N-ethylcarboxamide) and of adenosine on glucagon and insulin release from the in situ isolated blood-perfused pancreas in anesthetized dogs.

The effect of adenosine-5'-N-ethylcarboxamide, (NECA), a long-lasting adenosine derivative with pronounced vasoactivity was investigated on glucagon and insulin release from the in situ isolated blood perfused pancreas in the anesthetized dog: NECA (10(-9) to 10(-5) mol/l) led to a dose-dependent glucagon release. Insulin release was inhibited by NECA at low concentrations, but significantly increased at higher concentrations of the adenosine analogue. Similar effects were observed with infusion of adenosine at 10(-7) and 10(-6) mol/l. Aminophylline (10(-4) mol/l) produced a 10-fold attenuation of the actions of NECA. The preponderance of glucagon release at low concentrations of NECA and adenosine in contrast to that of insulin release at high concentrations may represent a local pancreatic regulatory mechanism of adenosine in glucose homeostasis.