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

Abstract

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.

Comparative effects of PACAP and VIP on pancreatic endocrine secretions and vascular resistance in rat

“…Our data are supported by a recent study showing by in situ hybridization that VIP, receptor mRNA is clearly associated with blood vessels in rat pancreas (Usdin et al, 1994). It has been shown that VIP increased whole pancreas blood flow without affecting islet blood flow in rat in vivo and thus, there is no correlation between increase in islet blood flow and hormone secretions (Jansson, 1994). On the other hand, it must be noted that, at the high concentration of 10-7M, the vasodilator effect of PACAP was reversed to a clear transient decrease in pancreatic flow rate.…”

“…Indeed, no study has compared the effect of these peptides on glucagon secretion; on the other hand, for insulin secretion it has been reported that PACAP was more potent than VIP suggesting an action at a PACAP receptor type I (Yada et al, 1994) whereas it has been shown that receptors with similar binding properties to the type II are expressed in an insulin-secreting fi cell line (Inagaki et al, 1994). In addition, these peptides are known to exhibit a vasolidator effect in various vascular beds (see Christophe, 1993) and VIP has been reported to increase whole pancreatic blood flow in rat (Jansson, 1994). The present study was designed to compare the effects of PACAP and VIP on pancreatic endocrine secretions and vascular resistance in order to characterize the PACAP/VIP receptor types involved.…”

Immunodetection of cocaine- and amphetamine-regulated transcript in bovine pancreas

“…Intrapancreatic neurons and ganglia, blood vessel innervating nerve fibres, also constitute a substantial source of the CART peptide, which is, in turn, associated with regulation of the exocrine parts, while VIP presence at nerve endings has a stimulating effect on local blood flow (Jansson, 1994).…”

Characterisation of CART-containing neurons and cells in the porcine pancreas, gastro-intestinal tract, adrenal and thyroid glands

“…Thus, one function of CART in the intrapancreatic neurons could be to regulate exocrine secretion. Since we found that CART is localised to VIP containing neurons, and since VIP is known to exert stimulatory effects on local blood flow [41] and on exocrine secretion [42], it is not inconceivable that CART may modulate these VIP-induced effects on the exocrine pancreas. In addition, CART in pancreatic neurons may be neuroprotective and/or neurotrophic in situations of stress or injury, since such actions of CART have been observed in certain central and enteric neurons [17,43-45].…”