Effects of Intraluminal Pressure in the Colon on its Vascular Pressure-Flow Relationships∗

Distension of the small intestine has been shown to result in increased intraluminal pressure and resistance of blood flow (1). Welsh (2) concluded that mucosal blood flow in the colon is increased during periods of increased motility. Other studies showed that total colon blood flow is decreased during rhythmic contraction and by distension of the colon (3). Arterial pressure-flow studies have given evidence of autoregulation of blood flow in the small intestine (4) and colon (5). Elevation of venous pressure results in increased resistance in the intestine and the responses are abolished by the infusion of papaverine (5, 6). In the present paper data are given on the effects of distension of the colon on these vascular responses to changes in arterial or venous pressure.Methods.Dogs weighing 20-25 kg were anesthetized with pentobarbital (30 mg/kg, iv). The colon was exposed and freed of its mesenteric attachments. Heparin (500 units/kg, iv) was given. Then a second dog to serve as a perfusion donor was anesthetized and heparinized.