Intestinal mucosal oxygenation influences absorptive hyperemia

Abstract

Intestinal villus oxygen tension (PO2) is decreased from normal values of 14-17 to 4-7 mmHg, and blood flow is nearly doubled during glucose absorption. The current study evaluated The role of oxygen supply to the mucosa in the absorptive hyperemia mechanism. With a constant PO2 (40-45 mmHg) over the intestinal muscle layer, the mucosal tissue PO2 increased only 4-5 mmHg, and intestinal blood flow decreased from about 125 to 65% of control (PO2 = 4045) as the mucosal solution PO2 increased from 5 to 75 mmHg. When glucose was present (100 mg/100 mL), mucosal tissue PO2 was s-7 mmHg at mucosal suffusion PO2 of s-75 mmHg. When glucose was present (100 mg/100 mL), mucosal tissue PO2 was s-7 mmHg at mucosal suffusion PO2 of s-75 mmHg. Blood flow in the presence of glucose was 210 and 110% of control at a solution PO2 of 5-10 and 70-75 mmHg. Tissue PO2 in the vicinity of the submucosal series arterioles was only slightly affected by all of the manipulations described. At rest or during glucose exposure, elevation of mucosal solution PO2 caused constriction, and lowering the mucosal solution PO2 caused dilation even though tissue PO2 in the various regions of the bowel wall remained nearly constant. The data indicate that the supply of oxygen available for the tissue rather than the actual tissue PO2 is best correlated to oxygen's role in control of arterioles throughout the intestine during absorptive hyperemia.