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Endogenous noradrenaline release from guinea‐pig isolated trachea is inhibited by activation of M 2 receptors
Author(s) -
Racké Kurt,
Hey Claudia,
Wessler Ignaz
Publication year - 1992
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1992.tb14454.x
Subject(s) - oxotremorine , muscarinic acetylcholine receptor , pirenzepine , methoctramine , guinea pig , stimulation , agonist , endocrinology , medicine , receptor , endogeny , muscarinic agonist , chemistry , atropine , acetylcholine , biology
Overflow of endogenous noradrenaline (NA) from guinea‐pig isolated tracheae was evoked by electrical field stimulation (3 Hz, 540 pulses). The muscarinic receptor agonist oxotremorine inhibited the evoked overflow of NA in a concentration‐dependent manner (EC 50 84 n m ). Methoctramine, pirenzepine and p ‐fluoro‐hexahydrosiladiphenidol (each 1 μ m ) shifted the concentration‐response curves of oxotremorine to the right with apparent pA 2 values of 7.60, 6.74 and 6.18, respectively. It is concluded that sympathetic nerve terminals in the guinea‐pig trachea are endowed with inhibitory muscarinic M 2 receptors.