Effect of atropine on bile-oleic acid-induced alterations in dog jejunal hemodynamics, oxygenation, and net transmucosal water movement

Abstract

The effects of intraluminal bile-oleic acid on jejunal blood flow, oxygen uptake, net transmucosal fluid flux, and mucosal infrastructure were studied in isolated autoperfused jejunal segments before and after cholinergic blockage with atropine. Bile-oleic acid increased jejunal blood flow (40%), decreased oxygen extraction (24%), and increased oxygen uptake (15%). Cholinergic blockade did not abolish the bile-oleic acid-induced changes in these parameters. Bile-oleic acid induced net fluid secretion or significantly depressed absorption. Cholinergic blockade reversed net volume secretion to absorption or attenuated the depression of absorption produced by bile-oleic acid. Ultrastructural analyses of tissue samples taken during bile-oleic acid-induced secretion indicate major structural damage to the mucosal membrane which was not affected by cholingergic blockade. The physiologic and ultrastructural data acquired in this study suggest that: (a) the effects of bile-oleic acid on net transmucosal water movement are reversed by cholinergic blockade and (b) the hyperemia, increased oxygen consumption, and morphologic alterations induced by bile-oleic acid are not affected by cholinergic blockade. The results of this study may have important implications in steatorrheal diseases in that, atropine may alleviate the diarrhea induced by the presence of excess lipid in chyme without compromising the intestinal hyperemia and enhanced oxygen delivery required to meet the increased metabolic demands during nutrient absorption.