Changes in colonic motility following abdominal irradiation in dogs.

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...