Molecular characterization of autonomic and neuropeptide receptors

© 1994 by Marcel Dekker, Inc. All Rights Reserved. For many years, it was believed that the control of airway function was dependent on the balance between the cholinergic (parasympathetic) and adrenergic (sympathetic) nervous systems. The cholinergic system is considered excitatory because it plays a role in maintaining airway tone and in mediating acute bronchospastic responses (Casale, 1993). The effect of acetylcholine to produce narrowing of the airways is blocked by atropine, indicating that this effect is mediated by muscarinic acetylcholine receptors (Colebatch and Halmagyi, 1963; Olsen et al., 1965). In contrast, the adrenergic system in the lung is considered inhibitory because stimulation of β-adrenergic receptors produces relaxation of bronchial smooth muscle. The beta-blockade theory of the pathogenesis of asthma from Szentivanyi (1968) proposed that asthma was related to an imbalance in the autonomic control of airway diameter due to a decrease in β-adrenergic sensitivity in bronchial smooth muscle, mucus glands, and mucosal blood vessels