Some studies on the release of histamine from mast cells stimulated with polylysine.

1 Polylysine is an extremely potent releaser of histamine from rat peritoneal mast cells. Isolated mesenteric mast cells of the rat also respond to the secretagogue but guinea-pig mesenteric cells are unreactive. 2 The release does not require the presence of extracellular calcium ions but shows some dependence on internal stores of the cation. 3 The effect of polylysine is blocked by extremes of temperature and by metabolic inhibitors. 4 The release is very rapid and is virtually complete within 10 s of adding the inducer. 5 The release is unaffected by the anti-allergic drug, doxantrazole, but is inhibited by theophylline and disodium cromoglycate. The latter compounds are effective in both the presence and absence of added calcium. This result is discussed in terms of the postulated effect of the drugs on calcium transport.