Colonic myoelectrical activity and propulsion in the dog.

Electrical spike activity was recorded on the colon of the dog. The duration of the bursts of the spike was used to divide the spike activity into two different types: long and short spike bursts (LSB and SSB). LSBs lasted from 7 (ascending) to 37 sec (descending) and SSBs lasted about 1 sec, independent of the site. These measurements were applied to colons of colostomized dogs for which the colonic transit time was negatively correlated to the LSBs expressed as percent of the time. The effects of high- and low-residue diets were tested. Intake of large amounts of dry food was associated with an increase of the LSB activity. A meat diet was accompanied with an increase of the SSB activity. These results suggest a propulsive effect for the LSBs stimulated by large amounts of colonic contents while the SSB activity may reflect some degree of emptiness.