Roffel_1990_Pulm.Pharmacol_3_47

The muscarinic receptor subtype involved in human airway smooth muscle contraction was characterised for the first time, using subtype-selective muscarinic antagonists. It was demonstrated that methacholine-induced contraction of central (trachea) and peripheral (small bronchi) airway smooth muscle preparations was antagonised by pirenzepine, AF-DX 116, 4-DAMP methobromide, hexahydrosiladifenidol, and methoctramine with pA2-values characteristic of M3 (smooth muscle/glandular) muscarinic receptors. Since these pA2-values demonstrate significant correlations with those found in bovine and guinea-pig tracheal smooth muscle contraction, it is concluded that these animal tissues provide a good model for the study of M3 subtype-selective muscarinic antagonists to be used as bronchodilators.