§4.111 



DIGESTIVE GLANDS 



125 



4-1); but, as its name implies, it stimulates those gland cells which 

 secrete the digestive enzymes. Vagal stimulation also facilitates 

 the secretion of enzymes ; but the action of the hormone persists 

 after bilateral section of both the vagus and the sympathetic 

 nerves. Experiments (Wang and Grossman, 1951) on trans- 

 planting the pancreas, to eliminate any possibility of nerve con- 



Fig. 4-5. Diagram, as in Fig. 4-4, showing the effectiveness of 

 various substances in stimulating enzyme secretion from a trans- 

 planted pancreas, for 3-5 dogs in each case. The change in enzyme 

 secretion indicates the quantity of pancreozymin released into the 

 circulation from the duodenum, in response to each substance. 

 Peptones and amino acids are more effective than acid in stimu- 

 lating pancreozymin secretion (from Wang and Grossman, 1951) 



nection between the duodenum and the pancreas, prove the 

 presence and independent action of pancreozymin as a hormone. 

 The stimuli that have been reported to cause the release of 

 pancreozymin include soap, peptone, casein, starch, various sugars 

 and even distilled water, introduced into the duodenum ; they have 

 now been rigorously tested on pancreatic transplants. These 

 experiments show that peptones and the amines, leucine, trypto- 

 phane and phenylalanine, resuhing from protein digestion, are 

 more effective than acid (Fig. 4-5). 



