抄録
In order to investigate the effect of vasoactive intestinal peptide (VIP) upon the secretion of insulin and glucagon, experimental studies were carried out using a local circulation of the pancreas of anesthetized dogs. VIP was infused into the pancreatic artery in doses of 20, 100, 200 and 400ng for 10 minutes. The blood glucose level in the femoral artery did not change during and after VIP infusion. Blood flow rate in the pancreatic vein did not change throughout the experiment with graded doses of VIP. The secretion rate of insulin in the pancreatic vein increased transiently during the infusion of 20ng of VIP but a constant and significant increase in insulin secretion was observed in the experiment with a dose of 400ng of VIP. In contrast, the glucagon secretion in the pancreatic vein increased significantly following the infusion of VIP in doses of 20 to 400ng for 10 minutes.
To determine the regulation of VIP secretion, the plasma levels of VIP were measured in the animal experiment as well as in human study. Radioimmunoassay for VIP used in the present study was established by Yanaihara and in the assay system 10pg of VIP could be detected. The fasting levels of plasma VIP did not exceed 200pg/ml in patients with diarrhea or diabetes mellitus, except for the cases with renal failure. Plasma VIP did not change during glucose tolerance test. A small rise in VIP was observed in diabetic patients during arginine infusion test. When glucose (2g/kg) or amino acids mixture (1g/kg) was infused into the duodenum of the conscious dogs, plasma VIP in the mesenteric vein as well as in the vena cava increaed by 30 minutes. However, delayed rise in plasma VIP was observed in the mesenteric vein after butter Administration in dogs. From the present studies, it was suggested that VIP secreted from the gut during the absorption of nutrients might modulate the secretion of insulin and glucagon from the pancreas.
