Acetylcholine-induced relaxation and contraction of rat tail artery: Role of muscarinic receptor subtypes

Acetylcholine (Ach)-dose responses were observed in phenylephrine- contracted perfused segments of the rat tail artery in the presence or absence of muscarinic receptor subtype antagonists [pirenzepine, M1; gallamine, M2 or 4-diphenylacetoxy N-methylpiperidine methiodide (4-DAMP), M3]. Dose responses to each antagonist was also observed in the presence or absence of Ach. Arterial endothelium was either left intact, denuded with saponin or was …