Wu Y, Fang L B, Yang Q H
Department of Pharmacology, School of Medicine, Zhejiang University, Hangzhou 310006, China.
Acta Pharmacol Sin. 2000 Oct;21(10):945-8.
To study the effect of nociceptin (orphanin FQ), a newly discovered heptadecapeptide, on cholinergic constrictions in isolated trachea and bronchus of rat.
The electric field stimulation (EFS) induced a monophasic constriction, which was due to an activation of the cholinergic nerves.
Nociceptin 0.001-0.1 mumol/L inhibited cholinergic constriction in a concentration-dependent manner. IC50 (95% of confidence limits) were 0.06 (0.04-0.08) mumol/L and 0.07 (0.05-0.1) mumol/L in tracheae and bronchi respectively. The constrictions inhibited by nociceptin 0.01 mumol/L in traheae and bronchi were (58 +/- 32)% and (60 +/- 26)% respectively compared with the control, in which nociceptin was not applied. After pretreatment with naloxone 0.1 mumol/L, the constrictions were (60 +/- 19)% and (54 +/- 20)% (P > 0.05 vs the above figures). However, the constrictions induced by exogenous acetylcholine were unaffected by nociceptin 0.01 mumol/L. kappa-Opioid receptor agonist, U-50488H (0.01-1 mumol/L) did not affect the EFS-induced cholinergic constrictions in rat airways.
Nociceptin inhibits EFS-induced cholinergic constriction, which is not affected by naloxone in rat airways.
