title: Recognition of the 'calcium paradox' and the effects of verapamil and gallopamil in human adenoidal mast cells.
abstract: Human mast cells from adenoids show when resuspended in medium containing 10(-3) M CaCl2 after their temporary exposure to Ca2+-free saline for about 20 min an irreversible reduction of responsiveness to a variety of stimuli: The histamine release induced by concanavalin A or ionophore A 23187 is only 30-50% of the one obtained in cells which were kept in 10(-3) M Ca2+ throughout the experiment. This phenomenon called 'calcium paradox' can be almost entirely avoided if the cells are temporarily exposed to 10(-4) M Ca2+ instead of Ca2+-free saline. Number yields, average histamine contents of mast cells and the rate of the spontaneous histamine release are not affected by the transitory lack of Ca2+, nor is the histamine release enhancing effect of adenosine. At 10(-3) M Ca2+ concentration the calcium antagonists verapamil or gallopamil cause a significant inhibition of the Con A-induced histamine release only at concentrations much higher (10(-4) M than those effective in smooth muscle preparations. The actions of both calcium antagonists were not affected by the presence of added extracellular adenosine.
mesh_terms: D000234:Adenoids / Q000166:cytology; D002118:Calcium / Q000502:physiology*; D003208:Concanavalin A / Q000494:pharmacology; D005711:Gallopamil / Q000494:pharmacology*; D006636:Histamine Release / Q000187:drug effects; D006801:Humans; D008407:Mast Cells / Q000187:drug effects* / Q000378:metabolism; D014700:Verapamil / Q000494:pharmacology*
chemical_list: D003208:Concanavalin A; D005711:Gallopamil; D014700:Verapamil; D002118:Calcium