Airway smooth muscle, asthma, and calcium ions.

The intracellular concentration of free Ca2+ ions regulates many functions of cells including secretion, contraction, transport processes, and motility, among others. All of the pathogenetic processes in asthmatic airways are Ca2+-dependent phenomena: excitation-contraction coupling in smooth muscle, stimulus-secretion coupling in mast cells and mucous glands, nerve impulse initiation and conduction, and the development of inflammatory infiltration. Ca2+ entry blockers such as nifedipine and verapamil may affect exercise-induced asthma, airway tone, mast cell mediator release, and experimental anaphylaxis. Calmodulin-active drugs can inhibit smooth muscle contraction and mediator release. A new generation of Ca2+ antagonists may find a role in the management of asthma.