Chapter IX 

 HIST AMINE IN TISSUE MAST CELLS: NORMAL TISSUES 



RESULTS OBTAINED BY COMBINING HISTOLOGICAL AND 

 PHARMACOLOGICAL TECHNIQUES 



THE evidence cited in the previous section indicates that the tissue mast 

 cells of the rat undergo profound morphological changes following 

 contact with chemical histamine-liberators. It is now necessary to 

 ascertain whether the mast cells are in fact the source of the histamine which is 

 released during this reaction: in other words, are the initial values for histamine 

 in normal tissues proportionate to their mast-cell contents, and do these values 

 vary with the morphological changes in the mast cells which follow the 

 administration of the chemical histamine-liberators? 



It will be recalled that Jorpes used the first of the above criteria in seeking 

 the location of heparin in the tissues. We therefore first confirmed the mast- 

 cell contents of the tissues used by him, for which the corresponding heparin 

 values are also available (Jorpes, 1946), and estimated their histamine contents 

 (Riley and West, 1953). 



Materials and methods 



All material was obtained fresh, either at the slaughter-house or in the 

 laboratory. Tissue blocks for mast cells were fixed, as before, in formol 

 corrosive and stained with toluidine blue. 



Representative samples of fresh tissue for histamine assay were weighed and 

 placed as soon as possible in a known volume of 10 per cent trichloracetic acid, 

 usually 1 ml. acid per 1 g. tissue, or twice that volume of acid if the tissue was 

 not adequately covered. Thereafter the tissue was chopped with scissors, or 

 if tough, ground with a little sand in a mortar, to ensure complete extraction 

 of the histamine into the acid. After a minimum period of one hour the 

 extract was centrifuged and the clear supernatant then shaken vigorously four 

 times with a fourfold volume of ether (or shaken further if the p\\ was still 

 below 6-0) in order to remove the acid. 



The assay itself was made against a standard solution of histamine acid 

 phosphate (10~ 3 ) either on the conventional guinea pig ileum preparation or 

 on the blood pressure of the atropinized cat. All values are expressed as [xg 

 histamine base per gram wet weight of tissue. 



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