Egan_1985_Br.J.Pharmacol_85_733

Intracellular recordings were made from neurones of the rat locus coeruleus in vitro. Acetylcholine increased the firing rate by depolarizing the membrane; both muscarinic and nicotinic antagonists partially reduced this effect. In hexamethonium, pirenzepine shifted the acetylcholine dose-response curve to the right with an equilibrium dissociation constant of 200 nM, indicating an interaction with a m2-type of muscarinic receptor.