Effects of ligation and morphine on electric and motor activity of dog duodenum

Abstract

Electric activities and intraluminal pressures were simultaneously recorded from the duodenum of unanesthetized dogs. The effects of ligation and morphine were examined. The temporal relation of spike potentials to the basic electric rhythm (BER) was not altered by ligation or morphine. The BER below the ligature was decreased by extending the distal portion of the electrical complex. The propagation of the BER was also disturbed to generate a pattern suggestive of multiple foci activity. The morphine-enhanced motor activity bore a 1:1 ratio with the altered BER. The maintenance of this ratio is taken as evidence that the BER governs the conditions for discharge of spike potentials which determine duodenal contractions. Spike potentials indicate smooth muscle activity, the number and duration determining the magnitude of contractions. The data advance the concept that duodenal rhythmic changes in pressure (type 1 contractions) do not migrate and are concerned with rhythmic segmentation rather than caudal propulsion.