Gastrointestinal blood flow in the dog.

• Measurement of blood flow to the individual gastrointestinal organs has been hampered by limitations of methodology. The oldest and most direct experimental technique for estimating blood flow to an organ is timed collection of its total venous outflow. Traumatic surgical procedures are required to accomplish such collections from the stomach, intestine, or colon. This method is not applicable to the pancreas, gall bladder, duodenum or esophagus because these latter organs are drained by multiple small vessels. Placement of flowmetering devices on or in the major vessels also requires relatively extensive operative manipulation. The complexity of the arterial inflow and venous outflow pathways of the gastrointestinal organs makes estimates for an individual organ by means of a flowmeter somewhat questionable. Furthermore, the flowmeter devices, whether based on thermal or electromagnetic principles, are generally more useful for estimating relative changes in blood flow than for determining absolute quantities. In recent years indicator clearance techniques have been developed which allow measurement of tissue blood flow with relatively little disturbance of normal function. The particular method used in the present study was the radiorubidium distribution technique. The first part of the investigation was an inquiry into the suitability of this method for measurement of blood flow to the various gastrointestinal organs. The method gave accurate estimates of total blood flow to the stomach, small intestine and colon. Indirect evidence suggested that it was probably suitable for pancreas, gall bladder and esophagus. In the second part of the study the