Differential effects of gastrointestinal Hormones on the blood flow of the alimentary tract of the dog

Abstract

The blood flow of the alimentary tract in anesthetized dogs was measured with radioactively labeled 15-micron microspheres before and after i.v. application of the gastrointestinal hormones glucagon, vasoactive intestinal polypeptide (VIP), secretin, and somatostatin. After 5 min glucagon in a dose of 75 micrograms/kg bolus + 5 micrograms/kg X min-1 infusion increased significantly the blood flow in liver, stomach, duodenum, jejunum, ileum, and colon as well as the cardiac output by 160%, 761%, 662%, 576%, 817.3%, 320%, and 108%, respectively. A dose of 3 ng/kg X min-1 resulted in reduction of the circulation in liver, gastric fundus, duodenum, and colon by 27.7%, 19.1%, 16.2%, and 10.7% after 5 min while the cardiac output was not affected. Vasoactive intestinal polypeptide (VIP) infused in a dose of 3.3 pmol/kg X min-1 for 5 min increased the blood flow in the pancreas by 30% and reduced it in the spleen and gastric corpus by 26.9% and 41.5%, respectively. Secretin, another member of the glucagon family, after a 5-min infusion of a dose of 0.5 CU/kg X min-1 increased the cardiac output by 49.96% and the renal circulation by 120.7%. In the gastrointestinal tract circulation of the gastric antrum was stimulated by 474%, of the duodenum by 93.5% and of the ileal mucosa by 178%. Infusion of the pancreatic hormone somatostatin (3.5 micrograms/kg bolus followed by infusion of 3.5 micrograms/kg X h-1) increased the blood flow in the liver by 13%, in the pancreas by 23.15%, and in the spleen by 29.8%, while it reduced it in the fundic mucosa by 17.1% and corpus mucosa by 28.8%. In summary, the gastrointestinal hormones examined exert marked and distinct effects on the circulation of the gastrointestinal tract, each hormone in different parts of the digestive tract. Thus, the local microcirculation of the gastrointestinal tract seems to be subject to hormonal in addition to nerval control.

Vasoactive Intestinal Polypeptide and Gastrin-Releasing Peptide Attenuate Hepatic Microvasculatory Disturbances following Intestinal Ischemia and Reperfusion

“…Similar effects from the bombesin-like peptide GRP have been documented, which has vasodilatory effects on mesenterial precapillary arterioles, whereas under physiological conditions it leads to vasoconstriction in renal proglomerular arterioles [29, 30, 31]. These hormonal vasodilatory effects leading to improved blood flow might be responsible for the attenuation of microcirculatory disturbances, hepatic dysfunction and mucosal injury we observed in our study.…”

Impact of Gastrin-Releasing Peptide on Intestinal Microcirculation after Ischemia-Reperfusion in Rats

“…Red blood cell velocity even exceeded that one of normal controls. These results are well in accordance with the vasodilative effect of GRP on precapillary arterioles described previously [37, 38, 39]rather than a direct action at the capillary level. However, specific GRP receptors that could explain the vasoactive effect of GRP [40]have not yet …”

Modulation of Immune Checkpoints and Graft-versus-Leukemia in Allogeneic Transplants by Antagonizing Vasoactive Intestinal Peptide Signaling

“…VIP decreases Th1 chemokine expression (CCR5 ligands, CCL3, CCL4, and CCL5 expression)(3) and deactivates CCR5 signaling by dephosphorylation of CCR5(39), consistent with our observation of increased retention of CCR5 + donor T-cells in lymphoid organs of VIPhyb-treated mice. Furthermore, changes in splanchnic circulation induced by VIP may be relevant, since VIP reduces blood flow to the spleen (40,41). Thus VIPhyb-treatment led to retention of activated T-cells in lymphoid organs, and reduced their homing to GvHD target organs(42).…”