Nitrergic and purinergic mechanisms evoke inhibitory neuromuscular transmission in the human small intestine. Issue 3 (25th December 2013)

• Record Type: Journal Article
• Authors: Gallego, D.; Malagelada, C.; Accarino, A.; De Giorgio, R.; Malagelada, J. R.; Azpiroz, F.; Jimenez, M.
• Is Part Of: Neurogastroenterology & motility. Volume 26:Issue 3(2014:Mar.)
• Page Start: 419
• Page End: 429
• Publication Date: 2013-12-25
• Subjects: Gastrointestinal system -- Motility -- Periodicals; Gastrointestinal system -- Innervation -- Periodicals; 616.33
• DOI: 10.1111/nmo.12293
• Languages: English
• ISSNs: 1350-1925

Abstract

<abstract abstract-type="main" id="nmo12293-abs-0001"> <title>Abstract</title> <sec id="nmo12293-sec-0001" sec-type="section"> <title>Background</title> <p>Inhibitory neuromuscular transmission in the human colon is due to nitrergic and purinergic (P2Y<sub>1</sub>‐mediated) inputs. The aim of this study was to determine the mechanisms of neuromuscular transmission in different regions of the human small intestine.</p> </sec> <sec id="nmo12293-sec-0002" sec-type="section"> <title>Methods</title> <p>Ileal (n = 6) and jejunal (n = 6) samples underwent histological examination and were studied using sharp microelectrodes in smooth muscle cells and conventional muscle bath techniques. Electrical field stimulation (EFS) was used to stimulate inhibitory neurons.</p> </sec> <sec id="nmo12293-sec-0003" sec-type="section"> <title>Key Results</title> <p>No histological abnormalities were found. Resting membrane potential was −39.7 ± 1.5 and −45.5 ± 2.1 mV in the jejunum and ileum, respectively. Slow waves and spontaneous contractions were recorded at a frequency of about 8–9 and 6–7 cpm in the jejunum and ileum, respectively. In non‐adrenergic, non‐cholinergic conditions, EFS caused an inhibitory junction potential and mechanical relaxation. Both responses were blocked by tissue incubation with the nitric oxide synthase inhibitor (Nω‐nitro‐<sc>l</sc>‐arginine 1 mM) and the P2Y<sub>1</sub> receptor blocker 2′‐deoxy‐N<sup>6</sup>‐methyladenosine 3′, 5′‐bisphosphate tetrasodium salt (MRS2179; 10 μM). Both exogenous addition of sodium nitroprusside (1 μM) and the preferential P2Y<sub>1</sub> receptor agonist ADPβS (1 μM) hyperpolarized and relaxed smooth muscle cells. MRS2179 (10 μM) blocked ADPβS‐induced responses.</p> </sec> <sec id="nmo12293-sec-0004" sec-type="section"> <title>Conclusions & Inferences</title> <p>Similar to colon, inhibitory neurotransmission in the human small intestine is mainly mediated by purinergic (via P2Y<sub>1</sub> receptors) and nitrergic inhibitory neurotransmission. Similar mechanisms of inhibitory neurotransmission are present in different regions of the human intestine.</p> </sec> </abstract>