Comparative effects of various calcium entry blockers and anti-asthmatic compounds on antigen-induced bronchoconstriction in rat and histamine release from rat mast cells.

The effects of four calcium entry blockers (diltiazem, nifedipine, mesudipine and verapamil) were studied on antigen-induced bronchoconstriction in sensitized rats and histamine release from rat mast cells, in comparison with compounds frequently used in atopic patients (theophylline, isoproterenol, disodium cromoglycate, ketotifen and clemastine). The four Ca2+ entry blockers produced a dose-related inhibition of the IgE-dependent bronchoconstriction in rat whereas the other drugs exhibited a weak effect or even were inactive. 48/80-induced histamine release was antagonized by nifedipine, verapamil and ketotifen. On the contrary, diltiazem, mesudipine, theophylline, isoproterenol, disodium cromoglycate and clemastine were not able to interfere with this release process. These data may suggest an important role of both extra- and intracellular calcium in such phenomena.