Prejunctional muscarinic receptors regulating neurotransmitter release in airways.
Prejunctional pA2 values of five muscarinic antagonists were determined in the guinea-pig trachea under stimulation conditions in which the antagonists alone did not enhance acetylcholine release. The antagonists were partly selective at M1 (pirenzepine), M2 (AQ-RA 741, himbacine) and M3 receptors (hexahydrosiladifenidol, dicyclomine). The profile of the antagonist affinities was different from that obtained at cardiac M2 receptors but resembled the profile reported in the literature for the cloned m4 receptor. This suggests that autoinhibition of acetylcholine release in the trachea is mediated via M4 receptors.
Kilbinger
H
H
Department of Pharmacology, University of Mainz, Germany.
von Bardeleben
R S
RS
Siefken
H
H
Wolf
D
D
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D002794:Choline / Q000378:metabolism; D004558:Electric Stimulation; D006168:Guinea Pigs; D006325:Heart Atria / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D018721:Muscarinic Agonists / Q000494:pharmacology; D018727:Muscarinic Antagonists / Q000378:metabolism / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism; D010095:Oxotremorine / Q000494:pharmacology; D011976:Receptors, Muscarinic / Q000378:metabolism*; D014132:Trachea / Q000187:drug effects* / Q000378:metabolism
D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; D011976:Receptors, Muscarinic; D010095:Oxotremorine; D002794:Choline; D000109:Acetylcholine