Effect of morphine and naloxone on the motor response of the human
esophagus to swallowing and distension.
Penagini, Roberto, Alessandra Picone, and Paolo A. Bianchi.
Cattedra di Gastroenterologia, University of Milan, IRCCS Ospedale
Maggiore, Milan, Italy
APStracts 3:0073G, 1996.
The effect of morphine on esophageal motility has been little
explored. In 8 healthy volunteers we studied the effect of iv
morphine (100[mu]g/kg) followed 60 min later by iv naloxone
(80[mu]g/kg), and of iv naloxone alone (80[mu]g/kg) on the esophageal
motor response to swallowing and 30-sec intraluminal distensions (4,
6, 8 and 10 ml) during two separate experiments. Morphine increased
(p<0.01) the velocity but did not alter the amplitude or
duration of primary peristalsis and it decreased the duration and
magnitude of swallow-induced lower esophageal sphincter (LES)
relaxation (p<0.01). It also markedly increased contractile
activity below the balloon at high distending volumes (p<0.05)
and decreased the magnitude of distension-induced LES relaxation
(p<0.05) but did not affect contractile activity above the
balloon. All effects were reversed by naloxone. The latter alone did
not influence the esophageal response to swallowing or distension.
Conclusions: 1) morphine exerts effects on the response of the human
esophagus to swallowing and intraluminal distension, which are
consistent with an action at the level of the inhibitory neural
pathways, 2) these effects occur through opioid receptors, and 3)
endogenous opioids do not seem to control esophageal motility at
least through [mu] receptors.
Received 30 March 1995; accepted in final form 26 March 1996.
APS Manuscript Number G131-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 16 April 96