AJP - GI Watch the video to see how APS reaches out to developing nations.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Gastrointest Liver Physiol 292: G154-G164, 2007. First published September 28, 2006; doi:10.1152/ajpgi.00173.2006
0193-1857/07 $8.00
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
292/1/G154    most recent
00173.2006v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
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 Web of Science (3)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Takeuchi, T.
Right arrow Articles by Azuma, Y.-T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Takeuchi, T.
Right arrow Articles by Azuma, Y.-T.

MUCOSAL BIOLOGY

M2 and M3 muscarinic receptors are involved in enteric nerve-mediated contraction of the mouse ileum: findings obtained with muscarinic-receptor knockout mouse

Tadayoshi Takeuchi,1 Keisuke Tanaka,1 Hidemitsu Nakajima,1 Minoru Matsui,2 and Yasu-Taka Azuma1

1Department of Veterinary Pharmacology, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai Osaka, Japan; and 2Division of Neuronal Network, Department of Basic Medical Sciences, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan

Submitted 26 April 2006 ; accepted in final form 11 July 2006

The involvement of muscarinic receptors in neurogenic responses of the ileum was studied in wild-type and muscarinic-receptor (M-receptor) knockout (KO) mice. Electrical field stimulation to the wild-type mouse ileum induced a biphasic response, a phasic and sustained contraction that was abolished by tetrodotoxin. The sustained contraction was prolonged for an extended period after the termination of electrical field stimulation. The phasic contraction was completely inhibited by atropine. In contrast, the sustained contraction was enhanced by atropine. Ileal strips prepared from M2-receptor KO mice exhibited a phasic contraction similar to that seen in wild-type mice and a sustained contraction that was larger than that in wild-type mice. In M3-receptor KO mice, the phasic contraction was smaller than that observed in wild-type mice. Acetylcholine exogenously administrated induced concentration-dependent contractions in strips isolated from wild-type, M2- and M3-receptor KO mice. However, contractions in M3-receptor KO mice shifted to the right. The sustained contraction was inhibited by capsaicin and neurokinin NK2 receptor antagonist, suggesting that it is mediated by substance P (SP). SP-induced contraction of M2-receptor KO mice did not differ from that of wild-type mice. SP immunoreactivity was located in enteric neurons, colocalized with M2 receptor immunoreactivity. These results suggest that atropine-sensitive phasic contraction is mainly mediated via the M3 receptor, and SP-mediated sustained contraction is negatively regulated by the M2 receptor at a presynaptic level.

M2- and M3-receptor knockout mouse; neurogenic response; acetylcholine-mediated phasic contraction; substance P-mediated tonic contraction


Address for reprint requests and other correspondence: T. Takeuchi, Dept. of Veterinary Pharmacology, Graduate School of Life and Environmental Sciences, Osaka Prefecture Univ., Sakai Osaka 599–8531, Japan (e-mail: takeuchi{at}vet.osakafu-u.ac.jp)






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online
Copyright © 2007 by the American Physiological Society.