Antral Waves Research Articles

Inductograph method for recording muscle activity, especially pyloric sphincter physiology

The inductograph method for registering in vivo muscle activity under physiological conditions is described. The method is applied to a study of the physiology of the pyloric sphincter region of well-trained, unanesthetized dogs, but is readily applicable for similar studies of the heart, uterus, skeletal muscle, etc. The motor activity of the pyloric sphincter and the pyloric antrum during fasting, feeding and gastric evacuation; the response of these regions to parasympatheticomimetic and sympatheticomimetic stimulation; and the role of the sphincter in gastric evacuation is presented. These studies show that the pyloric sphincter and the pyloric antrum are either quiescent and relaxed or the pyloric sphincter contracts momentarily in a rhythmic manner four to six times a minute in response to each propagated antral peristaltic wave. The inherent rhythm of the pyloric sphincter region is almost impossible to alter, but one or more contraction cycles may be inhibited by excitement, epinephrine, atropine, etc. or the inherent rhythm in a quiescent sphincter may be made manifest by feeding, pilocarpine, etc.

GASTRIC MOTILITY

I. RELATION OF ANTRAL CONTRACTION TO THE PYLORIC MECHANISM Cannon's1theory of the acid control of the pylorus has long been accepted by numerous physiologists. Briefly stated—it will be referred to again later—he holds that the pylorus is closed during digestion, that an acidity of 0.2 per cent, on the gastric side brings about its opening, and that the presence of acid in the duodenum effects its closure. The antral waves sweep on repeatedly to the pylorus, but this gateway remains closed until the continued secretion of hydrochloric acid brings up the concentration of the acidity to the level indicated above. The pylorus then opens and the next advancing wave forces the antral contents into the duodenum. But after studying numerous dogs2by the method previously described, it seemed that this theory could not explain some of the observations that were made. For it became more and more