Modulation of acetylcholine release from parasympathetic nerves innervating guinea-pig and human trachea by endomorphin-1 and -2
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Updated: Oct 19, 2026

In vitro Measurements of Tracheal Constriction Using Mice
Published on: June 25, 2012
H J Patel1, P Venkatesan, J Halfpenny
1Thoracic Medicine, Imperial College School of Medicine at the National Heart and Lung Institute, London, UK.
Abstract:
Endomorphin-1 and -2 (mu-opioid receptor agonists) produced a concentration-dependent and naloxone-sensitive inhibition of cholinergic contractile responses in guinea-pig trachea (at 10 microM, 46.1 +/- 8.0% and 33.8 +/- 8.6%, respectively). Endomorphin-1 and -2 also inhibited electrically-evoked acetylcholine release from cholinergic nerves innervating guinea-pig (at 0.1 microM, 41.8 +/- 10.9%; at 1 microM 60.1 +/- 6.3%, respectively) and human trachea (at 10 microM, 76.2 +/- 18.1%, and 77.7 +/- 14.3%, respectively). Naloxone prevented the inhibition by endomorphin-1 and -2 in both guinea-pig and human trachea, suggesting that these peptides can inhibit cholinergic, parasympathetic neurotransmission to the airways via the activation of classical opioid receptors.
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