AN IN-VITRO MODEL SUITABLE FOR STUDYING INSULIN-SECRETION IN AMPHIBIANS

The aim of this work was to develop an in vitro model suitable for stu dying insulin secretion in amphibians and for identifying agents capab le of either blocking or stimulating such a process in this group. For this purpose, pancreases from the toad Bufo arenarum were incubated f or 60 min at 25 degrees with several insulin secretagogues and blocker s, and the immunoreactive insulin released into the medium was measure d by radioimmunoassay. Under these experimental conditions, metabolic (glucose, ketoisocaproic acid, and arginine) and nonmetabolic (K+ and tolbutamide) agents as well as glucagon and acetylcholine significantl y stimulated the release of immunoreactive insulin. Conversely, somato statin and nifedipine blocked its secretion. All these agents exerted similar effects on the mammalian pancreas. These results prove that ou r model is a useful tool with which to study in vitro insulin secretio n in amphibians and to identify agents which affect hormone release in this group. (C) 1995 Academic Press, Inc.