Inhibition of allergic and non-allergic histamine secretion from rat peritoneal mast cells by calcium antagonists

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Abstract
1 Bepridil, TMB-8 (8-(diethylamino)octyl 3,4,5-trimethoxybenzoate hydrochloride),diltiazem, verapamil and nifedipine exerted concentration-dependent inhibition of antigen and calcium ionophore A23187-induced histamine release from rat peritoneal mast cells. 2 The inhibitory effects of verapamil and bepridil against calcium ionophore A23187-induced histamine secretion were antagonized by increased Ca2+ concentrations in the extracellular medium. These observations suggest that both agents act by interfering with the influx of Ca2+ into the mast cells. 3 The inhibitory activities of five different Ca2+ channel blockers on allergic and non-allergic histamine secretion from rat peritoneal mast cells varied considerably depending upon the nature of the secretagogue as well as concentration and type of Ca2+-antagonist examined.