Influence of alpha-cellulose on myoelectric activity of proximal canine colon

The relations between dietary fiber intake and myoelectric activity of the proximal canine colon were examined in four normal beagles fed four diets of varying fiber content in a randomized block design. The basal diet was a canned, meat-based product to which 3, 6, and 9% by weight of alpha-cellulose was added. Colonic motility was monitored using four bipolar Ag-AgCl electrodes. Two slow-wave frequencies were observed: 1) 18.4 +/- 0.1 cycles/min (cpm) and 2) 5.6 +/- 0.03 cpm. Fiber had no effect on either frequency. Spike activity showed three distinct patterns: 1) short bursts phase locked to slow waves of the 18.4 cpm frequency, 2) short bursts phase locked to slow waves of the 5.6 cpm frequency, and 3) prolonged sequences unrelated to slow waves, lasting from 5 to greater than 60 s and grouped in distinct aborally conducted bursts that occurred at a frequency of 2.9 +/- 0.1/h (SE). Fiber had no effect on the frequency of these bursts, but as fiber intake increased there was a linear decrease in burst duration from 11.4 +/- 0.6 min for the basal diet to 8.2 +/- 0.4 min for the high-fiber diet (P less than 0.001). We conclude that luminal factors influence spike burst activity in the proximal colon, because increments of undigestible fiber reduce burst duration on a dose-related basis.