Anticholinergic effect in the lung
Anticholinergic effects in the lung
Vagal stimulation of the respiratory tract's muscarinic-3 receptors causes airway constriction. By blocking this parasympathetic stimulation, the anticholinergic agents reduce ASM tone and lead to dilatation of the constricted airway.
There are three principle muscarinic (M) receptors: M1=postganglionic and CNS, M2=postsynaptic in heart nodes and myocard, and M3=postsynaptic in smooth muscle, vascular endothelium and secretory glands. The M4 stimulates molecular mechanisms like the M2receptors but its function is unclear. The M5 receptor is like the M1 receptor and is also found in the CNS, but its role is elusive.
The anticholinergic agents are the inhaled bronchodilators of first choice in asthma.
Extra info: The anticholinergic agents are primarily utilized as additional therapy after inhaled steroids and/or β-agonists have been applied. Anticholinergics are often used as first line agents in COPD.
Anticholinergic agents are airway specific.
Extra info: When administered by the inhaled route, anticholinergic remain primarily in the lung. However, systemic administration will affect all cholinergic receptors throughout the body and thus have multiple adverse effects.