Clinical Research
Copyright ©The Author(s) 2005. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jul 28, 2005; 11(28): 4367-4374
Published online Jul 28, 2005. doi: 10.3748/wjg.v11.i28.4367
Sensory-motor responses to mechanical stimulation of the esophagus after sensitization with acid
Asbjorn Mohr Drewes, Hariprasad Reddy, Camilla Staahl, Jan Pedersen, Peter Funch-Jensen, Lars Arendt-Nielsen, Hans Gregersen
Asbjorn Mohr Drewes, Hariprasad Reddy, Camilla Staahl, Jan Pedersen, Hans Gregersen, Center for Biomechanics and Pain, Department of Gastroenterology, Aalborg Hospital, Aarhus University Hospital, Aalborg, Denmark
Lars Arendt-Nielsen, Center for Sensory-Motor Interactions (SMI), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
Peter Funch-Jensen, Department of Surgical Gastroenterology L, Aarhus University Hospital, Aarhus, Denmark
Author contributions: All authors contributed equally to the work.
Supported by the "Det Obelske Familiefond," "Spar Nord Fonden and the Danish Technical Research Council
Correspondence to: Professor Asbjorn Mohr Drewes, MD, PhD, DMSc, Center for Biomechanics and Pain, Department of Medical Gastroenterology, Aalborg Hospital, DK-9000 Aalborg, Denmark. drewes@smi.auc.dk
Telephone: +45-99322505 Fax: +45-99322503
Received: November 15, 2004
Revised: December 20, 2004
Accepted: December 23, 2004
Published online: July 28, 2005
Abstract

AIM: Sensitization most likely plays an important role in chronic pain disorders, and such sensitization can be mimicked by experimental acid perfusion of the esophagus. The current study systematically investigated the sensory and motor responses of the esophagus to controlled mechanical stimuli before and after sensitization.

METHODS: Thirty healthy subjects were included. Distension of the distal esophagus with a balloon was performed before and after perfusion with 0.1 mol/L hydrochloric acid for 30 min. An impedance planimetry system was used to measure cross-sectional area, volume, pressure, and tension during the distensions. A new model allowed evaluation of the phasic contractions by the tension during contractions as a function of the initial muscle length before the contraction (comparable to the Frank-Starling law for the heart). Length-tension diagrams were used to evaluate the muscle tone before and after relaxation of the smooth muscle with butylscopolamine.

RESULTS: The sensitization resulted in allodynia and hyperalgesia to the distension volumes, and the degree of sensitization was related to the infused volume of acid. Furthermore, a nearly 50% increase in the evoked referred pain was seen after sensitization. The mechanical analysis demonstrated hyper-reactivity of the esophagus following acid perfusion, with an increased number and force of the phasic contractions, but the muscle tone did not change.

CONCLUSION: Acid perfusion of the esophagus sensitizes the sensory pathways and facilitates secondary contractions. The new model can be used to study abnormal sensory-motor mechanisms in visceral organs.

Keywords: Esophagus; Mechanical; Sensitization; Motility; Reflux; Pain