Submitted on May 12, 2003
Accepted on October 1, 2003
A New Model of Pacing in the Mouse Intestine
E. E. Daniel1*, Geoffrey Boddy1, Alicia Bong1, and WooJung Cho1
1 Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
* To whom correspondence should be addressed. E-mail: edaniel{at}ualberta.ca.
A simple model of pacing in mouse intestine to longitudinal (LM) as well as circular muscle (CM) has been developed. Undissected segments of LM or CM from mouse ileum or
jejunum were prepared to record contractions, nerve functions were inhibited and regular spontaneous contractions recorded. These had the properties expected of ICC paced contractions:
ileum slower than jejunum, inhibited but not abolished by nicardipine, reduced in frequency by cyclopiazonic acid, abolished by Ca 2+-free media and high temperature dependence (Q10~2.6-3.2). Nicardipine significantly reduced the pacing frequency in LM and CM. Intestinal segments
from W/WV mice had few, irregular contractions in CM, but had regular contractions in LM. Other differences were found between LM and CM which suggest that the control of pacing of LM differed from pacing of CM. Moreover, both LM and CM segments in wild type and W/WV and after cyclopiazonic acid responded to electrical pacing (50 V/cm, 50 or 100 ms) at 1 pps. Temperature < 26 °C inhibited electrically paced contractions in CM. These findings
suggest that the current models of ICC pacing need to be modified to apply to intact segments of
mouse intestine.
