EFFECTS OF IMIDAZOLINE DERIVATIVE RX871024 ON INSULIN, GLUCAGON, AND SOMATOSTATIN SECRETION FROM ISOLATED-PERFUSED RAT PANCREAS

The effects of the imidazoline compound RX871024 on arginine-induced i nsulin, glucagon, and somatostatin secretion in the isolated perfused rat pancreas have been investigated. Arginine induced biphasic insulin , glucagon, and somatostatin release when infused for 20 min at 20 mM concentration and 3.3 mM glucose in the medium. RX871024, at 10 mu M, did not influence basal hormone secretion but enhanced arginine-stimul ated insulin and somatostatin release, In contrast, glucagon secretion was markedly inhibited by 10 mu M imidazoline. RX871024 (1 mu M) did not significantly affect arginine-induced insulin and somatostatin sec retion but had an inhibitory effect on the second phase of glucagon re lease. In conclusion, RX871024 exerts a complex effect on the endocrin e pancreas challenged by arginine, comprising stimulation of insulin a nd somatostatin release and inhibition of glucagon release. These effe cts on hormone release probably constitute the main mechanism of the a ntidiabetogenic action of the imidazolines. (C) 1998 Academic Press.