CA2-ISLET CELLS SECRETING GLUCAGON AND SOMATOSTATIN( OSCILLATIONS IN PANCREATIC)

Immunohistochemically identified glucagon-releasing alpha(2)-cells fro m mouse pancreatic islets exhibited large amplitude oscillations of th e cytoplasmic Ca2+ concentration in 3 mM glucose. Other small islet ce lls with similar oscillations in the presence of 20 mM glucose were id entified as somatostatin-releasing alpha(1)-cells. The oscillations in both cell types resembled those induced by glucose in the surrounding larger beta-cells in starting from the basal level and disappearing a fter addition of the voltage-dependent Ca2+ channel blocker methoxyver apamil. The discovery that the alpha(1)- and alpha(2)-cells have intri nsic abilities to generate oscillatory Ca2+ signals indicates that pul satile release of somatostatin and glucagon do not require functional coupling to the beta-cells. (C) 1995 Academic Press. Inc.