Rhythmic Contractions of Stomach 



257 



contractions both in the stomach and intestine in intact ani- 

 mals (dog). 



Nicotin hydrochloride was administered intravenously in suc- 

 cessive gradually increasing doses. Artificial respiration was 

 employed as early as necessary and throughout the rest of the 

 experiment. Segmental contractions in the small intestine, peri- 

 stalsis in the stomach, rhythmic contractions of the pyloric sphinc- 

 ter, and antiperistalsis in the large intestine continued after the 

 administration of sufficient nicotin to abolish all responses either 

 to electrical stimulation of postganglionic sympathetic fibers or 

 the administration of adrenalin in relatively large doses (0.01 

 to 0.025 mg. per kg. of body weight). At this time the admin- 

 istration of adrenalin brought about no change in blood pressure. 

 It was found necessary, in order to secure these results, to 

 administer approximately three grams of nicotin hydrochloride 

 per kilogram of body weight. If now sufficient time was al- 

 lowed without the administration of more nicotin the conducting 

 mechanism recovered to such an extent that responses were 

 again elicited by electrical stimulation of postganglionic sym- 

 pathetic fibers or the administration of adrenalin in moderate 

 doses. 



The failure of relatively large doses of adrenalin, following 

 the administration of nicotin in the quantities stated above, to 

 bring about inhibition of the rhythmic contractions in the stom- 

 ach and intestine indicates at least a very great reduction in the 

 irritability of the myoneural junction. The failure of electrical 

 stimulation of postganglionic sympathetic fibers to bring about 

 any modification of these contractions indicates paralysis of 

 the nerve fibers or the myoneural junction or both. Therefore, 

 we may assume that the rhythmic contractions in the stomach, 

 pyloric sphincter, and the small and large intestine which con- 

 tinue when this stage in the nicotin paralysis is reached do so 

 in the absence of nervous influences. Consequently, the capacity 

 to execute rhythmic contractions is inherent in the gastroin- 

 testinal musculature. Furthermore, the rhythmic contractions 

 above indicated in the several parts of the gastro-intestinal canal 

 probably belong to the same category of functional motility. 



The results of these experiments do not demonstrate the ab- 

 sence of nervous control, under normal conditions, of the ryth- 

 mic contractions in any part of the gastro-intestinal canal. The 

 tracings recorded throughout the progress of any successful ex- 



