Figure 2
From: Is there a rationale and role for long-acting anticholinergic bronchodilators in asthma?
Autonomic regulation of airway smooth muscle tone.29,32,49,50 M1, M2, M3, muscarinic acetylcholine receptors 1, 2 and 3. + and − symbols represent signals increasing and decreasing airway smooth muscle tone, respectively. Note that non-adrenergic non-cholinergic autonomic pathways have been omitted for simplicity. Adapted from the study by Cazzola, et al.,32 with permission from the American Society for Pharmacology and Experimental Therapeutics.
