The Effect of Glucagon on Intestinal Motility and Blood Flow

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Abstract
The mechanism by which glucagon inhibits intestinal and vascular smooth muscle tone was studied in anesthetized cats. The intestinal motility was recorded by a volume recording device and the intestinal blood flow by connecting the left carotid artery via a drop recording unit with the superior mesenteric artery by a wide bore polyethylene tube. A femoral artery was used for recording of arterial pressure. Glucagon was administrated close intraarterially at different rates. In animals where the adrenals were left intact glucagoninfusion was followed by a considerable and immediate increase of intestinal blood flow and a somewhat delayed motility inhibition and blood pressure increase. When the adrenals were excluded glucagon still induced a blood flow increase. The motility inhibition and the blood pressure increase were both abolished, however. It is therefore suggested that glucagon exerts its action on the splanchnic area in two different ways, on the one hand by a direct effect on the vascular smooth muscles on the other hand by a release of catecholamines from the adrenal medullae which, in turn, inhibits intestinal smooth muscles.