Dictionary of Allergies .. Calcium ions

The release of histamine from mast cells following antigen-IgE binding is dependent on increased permeability to calcium ions through specific calcium channels in the cell membrane [1]. The secretion of mediators from mast cells can also be initiated by calcium ionophore or by direct injection of calcium ions into the cell, even in the aence of antigen. The release of mediators is thus regulated by extracellular and intracellular levels of calcium ions. [2]. Smooth muscle contraction is believed to occur by the mechanism of excitation-contraction coupling, which proceeds by depolarization of the cell membrane, influx of calcium ions into the cell via "calcium channels", and suequent interaction of the contractile proteins to cause the contraction [3]. The inhibition of calcium ion influx should be beneficial in allergic asthma, which involves both increases in bronchial hypereactivity and in the release of mast cell mediators [4].

References

1. Foreman, JC, Hallet MB, Mongar JL: The relationship between histamine secretion and 45-Ca uptake by mast cells. J. Physiol. 1977; 271: 193-214.

2. Mongar JL, Foreman GC: Control of histamine secretion, in Pepys J, Edwards Am (eds): The Mast Cell: Its Role in Health and Disease.

3.Tunbridge Wells, England, Pitman Medical, 1979, p. 30. Ebashi, S, Mikawa T, Hirata M, et al: Regulatory proteins of smooth muscle, in Casteels R, et al (eds): Excitation-Contraction Coupling in Smooth Muscle. Amsterdam, Elsevier/North-Holland Biomedical Press, 1977, p. 325.

4. Ferrari, M. et al: Diffrential effects of nifedipine and diltiazem on methacholine-induced bronchospasm in allergic asthma. Annals of Allergy, 1989, 63:196.