Neuronal activity of submucosal plexus of pyloric and ileocecal sphincteric regions of the cat gastrointestinal tract.

Extracellular recording of neuronal activity of the submucosal plexus of isolated pyloric and ileocecal sphincteric regions of cat intestine revealed both spontaneously active and silent neurons. The spontaneously active neurons consisted of fast- and slow-burst-type units and single-spike units. The silent neurons generated trains of spikes in response to deformation of the ganglion by the recording electrode or in response to local application of acetylcholine (Ach, 6 X 10(-5) -6 X 10(-2) microM/l) on the ganglion surface. Interactions of the excitatory type were made manifest by the synchronous activity of cells in the forms of a "driver-follower" interaction. Even more complex interactions of an excitatory and inhibitory character were observed when the beginning of discharge of one neuron caused activation of another which was followed by a pause as in the first neuron discharge. Analysis of the obtained data indicated a qualitative similarity of the neuronal organization of the submucosal plexus along the entire length of the alimentary canal. It is concluded that neurons of the plexus in sphincteric regions are interconnected in a single functional ensemble. However, the results of the study show that silent cells and single-spike neurons predominate and are located mainly at the mesenteric border and in the central band of the segment. This is evidently a reflection of the functional significance of the sphincters which prevent reflux within the alimentary canal.