Tachykinin NK2 receptors facilitate acetylcholine release from guinea-pig isolated trachea

Abstract

The release of newly synthesised [3H]acetylcholine was evoked by electrical field stimulation (5 Hz, 600 pulses) of epithelium-deprived guinea-pig trachea strips after sensory neuropeptides depletion with 3 μM capsaicin. The selective tachykinin NK2 receptor agonist [βAla8]neurokinin A-(4-10) increased in a concentration-dependent manner the electrically-induced release of [3H]acetylcholine. The facilitatory effect was antagonised by the selective non-peptide tachykinin NK2 receptor antagonist, SR 48968 (apparent pK(B) 8.9). The tachykinin NK1 and NK3 receptor agonists substance P methyl ester and senktide (both 10 and 100 nM), respectively, did not affect the evoked release of [3H]acetylcholine. It is concluded that the cholinergic nerves of guinea-pig trachea are endowed with prejunctional facilitatory tachykinin receptors of the NK2 subtype. Copyright (C) 2000 Elsevier Science B.V.