Characterization of the metabolic gradient in cat small intestine by layer fractionation

¹ Department of Physiology, University of Illinois, Urbana, Illinois

Gradations in oxygen consumption were observed in preparations of intact segments and in layer fractions of cat small intestine, which were excised following Nembutal anesthesia. Mechanical separation of the intestinal segments into layers provided a means for localization of these gradients within specific components of the intestinal wall. Gradients were found in segments of the submucosal and mucosal layers and in segments composed of circular muscle, submucosa, and mucosa; but none was observed in segments of the isolated circular muscle layer. Inactivation of one or both intrinsic ganglionic plexuses by mechanical separation abolished the gradient associated with the circular muscle layer. The tentative explanation of these findings is that the existence of a metabolic gradient within the intestine arises from two sources: a) a graded activity within the submucosal mucosal layers and b) a sharply graded differential oxygen consumption within the muscular layers which is controlled by the functional activity of the intrinsic ganglia.