Vago-vagal reflex motility patterns of the rat esophagus.
Lu, Wei Yang, and Detlef Bieger.
Division of Basic Medical Sciences, Faculty of Medicine, Memorial
University of Newfoundland, St. John's A1B 3V6 Canada
APStracts 5:0048R, 1998.
Esophageal reflex motility and its neural correlates were investigated
in 94 urethane anesthetized adult male albino rats. When distended by
means of a stationary balloon, the cervical and thoracic esophageal
portion responded with a single pressure wave (type I response),
whereas the diaphragmatic (intercrural) segment exhibited rhythmic
contractions (type II response). Balloon deflation resulted in an
off-response aboral to the balloon. Bilateral cervical vagotomy or
systemic D-tubocurarine abolished all types of reflex responses. Both
type I and type II responses were associated with multi-unit
discharges in the central subnucleus of the solitarius complex (NTSC)
and the compact formation of the nucleus ambiguus (AMBC). Type I
discharges consisted of single, type II of rhythmic 0.6 Hz bursts
that preceded intraesophageal pressure waves in a fixed phase
relationship, persisted after contralateral vagotomy and were
eliminated by ipsilateral vagotomy. During neuromuscular paralysis,
peak intraburst discharge rates were reduced in both the NTSC and
AMBC with a concomitant decrease in rhythmicity. It is concluded that
bolus-evoked peristalsis of the rat esophagus is 1) segmentally
organized; 2) effected by a bilateral uncrossed reflex arc consisting
of vagal viscerosensory, NTSC premotor, and AMBC motor neurons
innervating the striated muscle tunic; and 3) strongly facilitated by
reafferent feedback.
Received 12 June 1997; accepted in final form 2 February 1998.
APS Manuscript Number R366-7.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 19 February 1998