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This Article Full Text Full Text (PDF) Supplemental data All Versions of this Article: 582/1/229    most recent jphysiol.2007.130823v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lennerz, J. K. M. Articles by Reeh, P. W. Search for Related Content PubMed PubMed Citation Articles by Lennerz, J. K. M. Articles by Reeh, P. W. Related Collections Neuroscience

¹ Department of Physiology and Pathophysiology, Friedrich-Alexander-University Erlangen-Nürnberg, Universitätsstrasse 17, D-91054 Erlangen, Germany
² Department of Anatomy I, Friedrich-Alexander-University Erlangen-Nürnberg, Krankenhausstasse 9, 91054, Erlangen, Germany
³ Department of Otorhinolaryngology, University of Dresden Medical School, Fetscherstrasse 74, 01307, Dresden, Germany

Emerging evidence indicates a nociceptive role of vagal afferents. A distinct oesophageal innervation in the rat, with muscular and mucosal afferents travelling predominantly in the recurrent (RLN) and superior laryngeal nerve (SLN), respectively, enabled characterization of mucosal afferents with nociceptive properties, using novel isolated oesophagus–nerve preparations. SLN and RLN single-fibre recordings identified 55 and 14 units, respectively, with none conducting faster than 8.7 m s^–1. Mucosal response characteristics in the SLN distinguished mechanosensors (n = 13), mechanosensors with heat sensitivity (18) from those with cold sensitivity (19) and a mechanoinsensitive group (5). The mechanosensitive fibres, all slowly adapting, showed a unimodal distribution of mechanical thresholds (1.4–128 mN, peak 5.7 mN). No difference in response characteristics of C and A fibres was encountered. Mucosal proton stimulation (pH 5.4 for 3 min), mimicking gastro-oesophageal reflux disease (GORD), revealed in 31% of units a desensitizing response that peaked around 20 s and faded within 60 s. Cold stimulation (15°C) was proportionally encoded but the response showed slow adaptation. In contrast, the noxious heat (48°C) response showed no obvious adaptation with discharge rates reflecting the temperature's time course. Polymodal (69%) mucosal units, > 30% proton sensitive, were found in each fibre category and were considered nociceptors; they are tentatively attributed to vagal nerve endings type I, IV and V, previously morphologically described. All receptive fields were mapped and the distribution indicates that the posterior upper oesophagus may serve as a ‘cutbank’, detecting noxious matters, ingested or regurgitated, and triggering nocifensive reflexes such as bronchoconstriction in GORD.

(Received 3 March 2007; accepted after revision 26 April 2007; first published online 3 May 2007)
Corresponding author P. W. Reeh: Department of Physiology and Pathophysiology, Friedrich-Alexander-University Erlangen-Nürnberg, Universitätsstrasse 17, 91054 Erlangen, Germany. Email: reeh{at}physiologie1.uni-erlangen.de

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