The isolated perfused rat pancreas with duodenal exclusion was used to study the stimulation
of glucose-induced insulin release in response to chicken and porcine vasoactive intestinal
peptide (VIP). The insulin response to 5.5 or 16.7 mM glucose was markedly enhanced
by 750 pM porcine VIP and a concentration of 250 pM was still effective. At 250 pM,
chicken VIP exhibited a slightly higher potency than porcine VIP at both glucose concentrations.
The main difference between the two peptides was that the effect of porcine VIP disappeared
immediately after the peptide suppression but that of chicken VIP persisted for an
additional period of 8-10 min. Somatostatin (10 ng/ml) blocked the stimulatory effect
of both VIP molecules on glucose-induced insulin secretion. After suppression of VIP
and Somatostatin from the perfusion medium, insulin release increased to levels higher
than those with glucose alone in the case of the avian peptide, but not in that of
porcine VIP. The data are consistent with previous results in the literature on stimulation
of exocrine pancreas secretion and interaction with intestinal epithelium.
Vasoactive Intestinal Peptide
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Insulin Secretion
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Somatostatin
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Pancreas Perfusion
