Blood flow measurement in the canine pancreas.

There are two distinct types of preparation for studying blood flow and perfusion in the canine pancreas. The fust is the in vivo gland which can be examined in either anesthetized or ambulant dogs. Both flow and perfusion are under the influences of changes within the pan creas and of external stimuli, including nervous and hormonal factors. Investigators have evaluated blood flow and perfusion in the gland and the changes that occur in various metabolic states or following the administration ofhormones or drugs. In the second type of preparation blood flow is controlled artificially, so as to allow measurements of other parameters in the in situ or ex vivo gland In 1926 Babkin and Starling [4] described preparations ofboth an in situ and an ex vivo gIand Since then many modifications have been developed of both fue preparation ~ the model and the maintenance of flow or perfusion [1, 9, 19, 34, 35, 38, 39, 49, 50, 55,60,66,74]. This review is entire1y concerned with evaluation of the intact gland in the living animal. No further consideration is made of preparations in which blood flow has been maintained artificially. Methods of measurement of blood flow evaluate either total blood flow to the gland or tissue perfusion. B10od flow is a measure of the amount of bl00d passing through an organ, but does not indicate if all or onIy part of the volume recorded is available for tissue perfusion. Any blood passing through an arteriovenous shunt will be included in fue measurement although it does not pass through fue capillary red. Tissue perfusion indicates the volume of blood which actually passes through fue capillary bed and therefore represents tissue perfusion. It does not include any flow that passes through an arteriovenous shunt. If, however, fue entire blood flow to an organ participates in tissue perfusion, measurements of"flow" and "perfusion" will have equal value. T o measure flow in fue canine pancreas it is essential to be familiar with the anatomy of the blood supply which has been demonstrated to be from three main sources (Fig: 1) [17, 35, 42}. The su~rior pancreaticoduodenal artery, one of fue two end-arteries of fue gastroduodeDal artery, supplies fue head of the giand and part of fue body and uncinate process. Branches of the splenic artery supply a portion of!he body and tail, and fue inferior pancreaticoduodenal artery, arising from fue superior mesenteric artery, supplies part afilie uncinate process [35, 42]. The degree to which each artery supplies an afea is variable and anomalies occur. It is important to be aware that part of the flow from the superior and inferior pancreaticoduodenal arteries supplies fue duodenum through !he vascular connections be. tween the head of fue giand and fue duodenum. This review examines blood flow and perfusion measurements in fue canine pancreasfirst in anesthetized dogs and sUbsequentIy in ambulant animals. It is difficult to compare