EFFECTS OF HISTAMINE-LIBERATORS 



In a similar way 'Anthisan' countered the disruptive effect on mast cells of 

 the agar-serotoxin. Thus the disintegration of mast cells by both chemical 

 histamine-liberators and anaphylatoxin is prevented by pretreatment with an 

 antihistamine drug. 



Tissue spread of uterine fringe from rat treated with an anti-histamine drug before being 



subjected to the disruptive action of a chemical histamine-liberator. The mast cells have 



been protected. Toluidine blue ( X 108). 



Direct application of histamine-liberators to tissue spreads 



In a further attempt to gain information on the mode of action on mast 

 cells of the chemical histamine-liberators and the agar-activated serotoxin, 

 samples of the various solutions which had been prepared for injection were 

 applied directly to fresh spreads of rat mesentery, using the peritoneal inter- 

 spaces as cups for holding the solutions under test. 



Preliminary experiments soon showed that any aqueous solution, including 

 even normal saline, quickly causes diffusion of the metachromatic material 

 from the granules of mast cells, which later swell and burst, freeing such 

 granules as remain. Despite this limitation of the method, it was observed 

 that the diamidines exhibit the same avidity for mast cells in fresh spreads of 

 mesentery as they do when they reach the cells through the blood stream. If 



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