J Physiol Society Meetings
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
 QUICK SEARCH:   [advanced]


     


Physiology in Press

First published online on October 10, 2003.
Copyright © 2003 by The Physiological Society
This Article
Right arrow Full Text (Rapid PDF)
Right arrow All Versions of this Article:
553/3/911    most recent
jphysiol.2003.053140v1
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Reed, D. E
Right arrow Articles by Vanner, S. J
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Reed, D. E
Right arrow Articles by Vanner, S. J

Received August 8, 2003
Revised September 1, 2003
Accepted after revision October 6, 2003

Long vasodilator reflexes projecting through the myenteric plexus in guinea pig ileum

David E Reed1 and Stephen J Vanner1*

1 Queen's University

* To whom correspondence should be addressed. E-mail: vanners{at}hdh.kari.net.

This study examined enteric neural reflexes activating submucosal cholinergic vasodilator motoneurons, which innervate the final resistance vessels regulating mucosal blood flow. Videomicroscopy was employed to monitor dilation of submucosal arterioles in in vitro preparations from guinea pig ileum. Balloon distension of intact lumen evoked reflex vasodilatation and flat sheet preparations were employed to separate mucosal mechanical stimulation from intestinal distension. Mucosal stroking and balloon distension of the orad segment evoked vasodilatations >1.5 cm from the stimulating site. Mucosal stimulation was blocked by combined 5-HT3/5HT4 antagonists but distension-evoked responses were unaffected. Distension-evoked responses were also unaffected by nifedipine (5µM) or nifedipine (1µM) and wortmannin (300nM), suggesting stretch-activation rather than stretch-activated contraction was involved. Mucosal and distension-evoked responses were completely blocked when the myenteric plexus was surgically lesioned and were significantly inhibited by hexamethonium. The muscarinic antagonist 4-DAMP, which inhibits vasodilatations evoked by submucosal cholinergic vasodilator neurons, blocked dilations elicited by mucosal stimulation and balloon distension. Maximal dilations evoked with either sensory modality could be further enhanced when stimulated with the second modality. Dilations evoked by stimulation of the aborad segment were similar to those elicited in the orad segment. In conclusion, sensory mechanisms in the mucosa and muscularis propria activate vasodilator pathways in the myenteric plexus which project for significant distances in both ascending and descending directions before innervating submucosal arterioles. These reflexes could co-ordinate mucosal blood flow during multiple motor events such as peristalsis and intestinal mixing between propulsive events.


Key words: Afferent • Enteric reflexes • Vasodilatation







HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
Copyright © 2003 The Physiological Society.