A STUDY OF CERTAIN PROBLEMS RESULTING FROM VAGOTOMY IN DOGS WITH SPECIAL REFERENCE TO EMESIS

Abstract

An exptl. study was made in the dog before and after double vagotomy at different levels from the diaphragm anteriorly to the larynx. Particular attention was paid to the mechanism of emesis after vagotomy at high levels as well as the nervous control of the esophagus and the cardia. Regurgitation and emesis were a common consequence after vagotomy was done at, and especially higher than, the level of the hilus of the lung. Similar, although much less severe, phenomena occurred when nutrition was maintained only by parenteral feeding. The most important change after vagotomy at a high level in the dog is a complete loss of the peristaltic activity of the lower part of the esophagus. The lower two thirds of the esophagus were involved when vagotomy was done at any level above the arch of the aorta. The paralyzed esophagus was shown to retain food material or secretions which might be either partly pushed down to the stomach or partly regurgitated, apparently by the aid of the diffuse tonic contraction of the whole esophagus as a response to the rapid distention. Mere retention of the food in the paralyzed esophagus or distention of the esophagus was not the cause of the nausea and vomiting. The nausea and vomiting in these animals apparently resulted from irritation of the pharynx by the large amt. of the regurgitated material. The response to the pharyngeal irritation was more sensitive in many dogs after than before vagotomy. Coincidently in another series of expts., the response to appropriate doses of apomorphine was greater after than before vagotomy, a result that suggests a hyperexcitable status of the vomiting center. The possibility of irritation of the sectioned nerve stumps as the cause of vomiting was eliminated by similar findings in dogs after the exteriorized vagus nerve had been blocked with procaine hydrochloride. Similar consequences occurred after vagotomy in dogs on which complete sympathetic ganglionectomy had been performed. After complete sympathetic ganglionectomy, two dogs did not show any significant change of the function of the esophagus and the cardia and in a 3d dog the tone of the cardia was only slightly reduced. The peristalsis of the lower 2/3 of the esophagus was dependent on the extrinsic vagal supply. But it is not likely that the nerve supply to the upper 3d is derived from the branches arising from the vagus posterior to the larynx. The vagus contains both inhibitory and motor fibers to the cardia. There is evidence that the inhibitory fibers branch off from the main vagus trunks above the level of the arch of the aorta and take an intrinsic course in the esophageal wall to reach the cardia. When the cardia was freed from vagal control its tone was never increased but was reduced to different degrees in the majority of cases. In one dog, the tone of the cardia did not change after complete sympathetic ganglionectomy but was reduced by subsequent double cervical vagotomy.