AJP - Gastrointestinal and Liver Physiology, Vol 264, Issue 6 1024-G1030, Copyright © 1993 by American Physiological Society
Changes in colonic motility following abdominal irradiation in dogs
R. W. Summers and B. Hayek
Department of Internal Medicine, Department of Veterans Affairs Medical Center, Iowa City, Iowa 52240.
The purpose of the study was to compare colonic motor patterns before and
after a single abdominal dose of X-rays in dogs. Recordings were made from
five serosally implanted strain gauges at equidistant intervals along the
colon in seven dogs (2 dogs also had 2 jejunal electrodes and 1 had ileal
electrodes). Control recordings were made for 3 h in the fasted state and
daily for 2 wk after an absorbed X-ray dose of 938 cGy was delivered to the
abdomen. The duration of migrating colonic motor complexes decreased from
7.2 +/- 0.5 to 3.9 +/- 0.4 min while the mean amplitude fell from 10.3 +/-
0.6 to 1.8 +/- 0.2 g (P < 0.05). The rate of nonmigrating colonic motor
complex occurrence increased from 0.6 +/- 0.1 to 1.2 +/- 0.2 per hour (P
< 0.05). Colonic giant migrating contractions were rarely observed
during control recordings (2 in 80 h of recording). In contrast, repetitive
clusters of giant contractions were observed 5-8 days after exposure in
five of seven dogs (1.5/h) and were associated with restlessness, whining,
and passage of diarrheal stools (sometimes bloody) with nearly every
occurrence. The basic colonic motility patterns were less disrupted than
were jejunal myoelectric patterns at the same irradiation dosage. However,
the study demonstrates the important role of colonic giant migrating
contractions in pathological diarrheal states such as irradiation injury.
