AGMATINE IS NOT A GOOD CANDIDATE AS ENDOGENOUS LIGAND FOR IMIDAZOLINESITES OF PANCREATIC B-CELLS AND VASCULAR BED

In order to determine whether agmatine could be a putative endogenous ligand for imidazoline receptors mediating insulin secretion and vasoc onstriction, we compared its effects with those of the imidazoline, ef aroxan. Agmatine exhibited a much lower potency and efficacy than efar oxan on insulin secretion from rat pancreas perfused with 8.3 mM gluco se. On the other hand, in contrast to efaroxan (100 mu M), agmatine (3 mM) did not increase arginine-induced insulin release. In addition, a gmatine failed to reproduce the vasoconstrictor effect of efaroxan on pancreatic vessels. These results show that agmatine does not behave l ike efaroxan, an agonist for the imidazoline receptors mediating insul in secretion or vasoconstriction in the pancreas.