The effect of VIP/PACAP family of peptides on pancreatic blood flow and secretion in conscious dogs.
The effects of PACAP-38, PACAP-27, VIP and secretin on pancreatic blood flow were compared with those of meals in five conscious dogs using an ultrasound transit-time blood flow meter. All peptides (1-100 pmol/kg) induced dose-related increases of pancreatic blood flow, and fluid and bicarbonate secretion. Only PACAPs stimulated protein secretion. Both PACAPs at doses which did not stimulate pancreatic secretion, induced significant pancreatic vasodilatation. VIP was less potent than PACAP-38 and PACAP-27 at lower doses (1-25 pmol/kg), but was similar to PACAPs at higher doses. The maximal effects of PACAPs and VIP were comparable to those observed after meals. Secretin was a significant but weak vasodilator. When pancreatic secretion was maximally stimulated by secretin, a reduction of vascular resistance was 75% of postprandial peak levels. PACAP(6-38), a competitive antagonist of PACAP, inhibited pancreatic vascular responses to PACAPs, but not those to VIP and secretin. Its inhibitory effects on protein response to PACAPs were not significant. Atropine inhibited pancreatic protein but not the vascular effect of PACAP-27. Pancreatic vasodilatation by PACAPs appears to be mediated by both PACAP-specific and VIP/PACAP common receptors in dogs. PACAP, like VIP, is a good candidate for a mediator of atropine-resistant vasodilatation of the pancreas.
Ito
O
O
Department of Internal Medicine II, School of Medicine, Nagoya University, Japan.
Naruse
S
S
Kitagawa
M
M
Ishiguro
H
H
Ko
S
S
Nakajima
M
M
Hayakawa
T
T
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001639:Bicarbonates / Q000378:metabolism; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D003243:Consciousness; D004285:Dogs; D005260:Female; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D008297:Male; D009479:Neuropeptides / Q000494:pharmacology*; D010179:Pancreas / Q000098:blood supply* / Q000187:drug effects / Q000502:physiology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D012039:Regional Blood Flow / Q000187:drug effects*; D012633:Secretin / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000494:pharmacology
D001639:Bicarbonates; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D014665:Vasodilator Agents; D012633:Secretin; D014660:Vasoactive Intestinal Peptide; D001285:Atropine