King, Brian F;
(2021)
P2X3 receptors participate in purinergic inhibition of gastrointestinal smooth muscle.
Autonomic Neuroscience
, 234
, Article 102830. 10.1016/j.autneu.2021.102830.
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Abstract
The ATP analogue α,β-meATP is a potent relaxant of gastrointestinal smooth muscle, but its molecular target is uncertain inside the gut. α,β-meATP relaxed the carbachol-precontracted guinea-pig taenia coli in a concentration-dependent manner (EC50, 2.0 ± 0.1 μM). A luciferase-based assay confirmed that α,β-meATP solutions were minimally contaminated with ATP. α,β-meATP-evoked relaxations were inhibited by the competitive P2Y1 antagonist MRS2179 (pA2 = 5.36), but also by the competitive P2X3 antagonist, A-317491 (pA2 = 5.51). When MRS2179 and A-317491 were applied together, residual α,β-meATP responses converted from brief to prolonged relaxations. Sodium nitroprusside (a nitric oxide donor) also caused prolonged relaxations. Immunohistochemistry revealed that P2X3 receptors were present in myenteric ganglion cells and their varicose nerve terminals. The amplitude of α,β-meATP responses was not inhibited by TTX (NaV channel blocker) and ωCgTx (N-type CaV channel blocker). However, responses to α,β-meATP were inhibited by TEA (non-selective K+-channel blocker), indicating that relaxations involved opening K+-channels. The findings of this study are consistent with the conclusion that α,β-meATP stimulates Ca2+-permeable P2X3 receptors on varicose nerve terminals to release inhibitory nucleotides: 1) ATP and β-NAD release results in P2Y1-mediated brief relaxations; 2) another released transmitter (possibly NO) results in prolonged relaxations. Prejunctional P2X3 receptors represent a purinergic feed-forward mechanism to augment the action of inhibitory nerves on gut motility. This positive feed-forward mechanism may counter-balance the known negative feedback mechanism caused by adenosine and prejunctional A1 receptors on inhibitory motor nerves.
| Type: | Article |
|---|---|
| Title: | P2X3 receptors participate in purinergic inhibition of gastrointestinal smooth muscle |
| Location: | Netherlands |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.autneu.2021.102830 |
| Publisher version: | https://doi.org/10.1016/j.autneu.2021.102830 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Science & Technology, Life Sciences & Biomedicine, Neurosciences, Neurosciences & Neurology, Gastrointestinal tract, Purinergic transmission, ATP, PIG TAENIA-COLI, RELAXATION-MEDIATING P-2-PURINOCEPTORS, ADENINE-NUCLEOTIDE ANALOGS, NITRIC-OXIDE, NEUROMUSCULAR-TRANSMISSION, ALPHA,BETA-METHYLENE ATP, JUNCTION POTENTIALS, MYENTERIC NEURONS, P2Y(1) RECEPTORS, RAT |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Neuro, Physiology and Pharmacology |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10164363 |
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