Preservation of peristaltic reflex in the hypertrophied ileum of
the guinea pig.
Schulze-Delrieu, Konrad, Bruce Brown, Bob Herman, C Kice Brown, David
Lawrence, Siroos Shirazi, Tina Palmieri, and John Raab.
Gastroenterological Research Laboratories, VAMC, and the Medical
College of the University of Iowa, Iowa City, IA 52242
APStracts 2:0024G, 1995.
Chronic obstruction of the guinea pig ileum leads to distension and
muscular hypertrophy but how this affects passive biomechanical and
the nerve-mediated contractions and clearance known as peristaltic
reflex is unclear. Ileum of controls had a diameter of 3.0 1.1 mm and
a circular muscle thickness of 37.2 11.2 m; 4 weeks after placement
of a nonconstricting Gore-Tex band, the ileum was distended to 10.0
0.19 mm and its muscle had hypertrophied to 195.0 61.2 m,
respectively. Hypertrophied segments exceeded the controls in
capacity (e.g. 5.1 1.1 ml vs 1.1 0.2 ml at 6 cm), compliance and
hysteresis. Threshold volumes and pressures which triggered the
reflex were 3.3 1.3 ml and 3.1 .01 mmHg in hypertrophied versus 0.7
0.2 ml and 1.5 0.2 mmHg in controls. The diameter increase which
triggered the reflex was 1.4 0.1 mm in hypertrophied and 0.6 0.1 mm
in controls. Hypertrophied segments generated fewer contractions of
virtually the double amplitude, and failed to generate a pressure
differential between up and downstream sites as controls did.
Hypertophied segments generated larger stroke volumes and cumulative
clearance than controls. The ratio of antegrade to retrograde
clearance was similar in hypertrophied and control segments. The
length of the occluding segment in hypertrophied preparations
exceeded that of controls. Control contractions indented the
antimesenteric border and propagated antegrade from their site of
origin; bizarre writhing movements of hypertrophied segments made
their contractions difficult to monitor. Thus, distension and
muscular hypertrophy do not interfere with the ability of the
chronically obstructed guinea pig ileum to generate a peristaltic
reflex at least as readily and as powerful and as effective in
clearing the lumen as controls.
Received 14 June 1994; accepted in final form 3 February 1995.
APS Manuscript Number G231-4.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 February 1995.