Effects of thoracic spinal cord transection on colonic motor activity in rats

The resting colonic motor activity before and consecutively after spinal cord transection was recorded in male Sprague-Dawley rats. Recording probes were anchored surgically in the ascending and descending colon. Pressure changes were recorded on a dynograph using a low compliance perfusion system. A motility index took into account the amplitude, duration and frequency of contractions. Following a baseline recording animals were subjected either to spinal cord transection at T4 level or a sham operation. The recording sessions continued regularly on alternate days for the observation period of 3 weeks. Transection of the thoracic spinal cord markedly reduced the motility index of the distal colon on the first postoperative day. However, the motor activity gradually returned to pre-operative values after 7 days. Sham surgery did not influence the motor activity. These findings suggest that colonic motor activity is influenced by spinal shock and probably by different neural mechanisms mediating proximal and distal activities of the colon in rats.