Vasoactive intestinal polypeptide increases whole pancreatic blood flow but does not affect islet blood flow in the rat.

To evaluate the effects of vasoactive intestinal peptide (VIP) on whole pancreatic blood flow and islet blood flow in the rat, anaesthetized adult rats were injected intravenously for 90 s with VIP (500 ng/kg body weight). Immediately after the injection, the whole pancreatic and islet blood flows were measured with a microsphere technique. VIP markedly increased the former but did not affect the latter. Thus, the fraction of the whole pancreatic blood flow diverted through the islets was decreased. In separate experiments, the effects of VIP on the blood glucose and serum insulin concentrations of anaesthetized animals were investigated. VIP caused an acute increase (after 2 min) in the latter, but did not affect the former. It is concluded that VIP exerts its blood flow stimulatory properties only on the exocrine pancreas, and that it may increase the serum insulin concentrations without an associated change in islet blood perfusion.