The cholinergic effect on the airways is mediated by muscarinic receptors in the target airway cells. The activation of these receptors in bronchial smooth muscles initiates a cascade of biochemical events that result in bronchoconstriction.
Muscarinic receptors also mediate the secretory response to vagal nerve stimulation. Cholinergic agonists have a high secretory activity thereby stimulating the secretion of mucus from the submucosal glands and epithelial goblet cells, the main sources of mucus in the peripheral airways.
Therefore, both short- and long-acting anticholinergics are of major significance in the treatment of COPD.