Effects of caerulein and bombesin on insulin and glucagon secretion from the isolated, perfused rat pancreas

Caerulein and bombesin, peptides first isolated from amphibian skin, act upon the mammalian gastrointestinal tract. To determine if these peptides influence mammalian endocrine pancreatic function, we tested their effects on the isolated, perfused rat pancreas. In these experiments, we examined effects of constant infusions of either caerulein (10^-11 M through 10^-8 M) or bombesin (10^-11 M through 3.0·10^-7 M) which were superimposed upon glucose. Secretory studies consisted of a 20-min basal period (60 mg/dl glucose), then a 15-min infusion of glucose (150 mg/dl). Effects of the peptides (10^-9 M) upon the response to post-glucose arginine (168 mg/dl), cofusion with glucose (60 mg/dl) for 15 min, were also studied. Neither peptide had any effect on basal insulin secretion. However, both peptides had distinct effects on insulin responses to the stimuli. Both caerulein and bombesin produced enhancement of glucose-induced insulin secretion, increasing total insulin secretion in a dose-dependent manner. Only caerulein enhanced arginine-induced insulin secretion. These peptides had no effect upon arginine-induced glucagon secretion.