Dynamics of canine pancreatic blood flow and of insulin secretion during an intravenous glucose load.

Blood flow through the superior pancreaticoduodenal artery of anaesthetized dogs increases immediately after an i.v. glucose load and parallels to glycemia, but not to insulin output. Flow of superior mesenteric, and femoral arteries as well as of portal vein are also enhanced after rapid i.v. injections of glucose or mannitol. Extent and duration of all flow increases are dose-dependent and strongly related to the alterations of arterial plasma osmolality (maximum increase 24 mosmoles/kg). Heart rate, mean arterial blood pressure, and hematocrit remain unchanged after the first test minute. There is a considerable decrease of peripheral vascular resistance in the circulatory regions investigated. Flow through aorta ascendens is augmented for a short time. Possible mechanisms of vasodilatation are reflexes produced by osmoreceptors and/or local effects of osmolality on the tonus of vascular muscle. Within the physiological range pancreatic perfusion does not determine the amount of insulin released.