NON-MAST CELL HISTAMINE 



the second category are duodenum, ileum, caecum and liver in which the 

 histamine values show little change throughout. However, there is a third 

 category containing but one tissue, the pyloric half of the stomach, in which 

 a slight fall in histamine content from an initial high value is followed, not 

 merely by restoration of the initial level by day eleven, but by a considerable 



Table XXI 



Histamine values for a wide variety of tissues from rats, given compound 48 '80 and allowed to recover 



{a) on normal diet, (b) with added histamine, and (c) with added histidine. The only outstanding 



feature is the rapid over-compensation of the loss of histamine from the pyloric half of the stomach 



rise above its starting value. This conclusion is not altered by the findings in 

 later work that the initial value for pylorus in this experiment was somewhat 

 lower than normal. 



We therefore examined the histamine and mast-cell contents of the pyloric 

 portion of the stomach in more detail, scraping off the mucosa and estimating 

 histamine separately in mucosa and 'muscle' (i.e. the rest of the stomach wall). 

 The results of three such experiments are shown below in Table XXII. 



Table XXII 



Histamine values (\xg.jg. tissue) of the pyloric portion of rat stomach 



estimated (a) in intact tissue, and (b) after separation of the mucosa 



from the rest of the stomach wall (' muscle ') 



133 



