Non-invasive electrocologram: correlation between the electrical activity of the dog colonic muscle wall recorded by cutaneous and implanted electrodes.

Chronic experiments were performed on dogs with silver, bipolar, ball-shaped electrodes implanted on the colonic and of the gastric muscle wall. Cutaneous electrodes were placed on the abdominal wall, along the projection of descending colon and also of the stomach, at the beginning of each experiment. Slow waves were led off in the electrocolomyogram (EColMG), corresponding to low-amplitude waves in the non-invasive electrocologram (EColG) with a frequency of 6.39 +/- 0.58 cpm (type A). When bursts of spike potentials appeared with the slow waves in the EColMG, increase of the amplitude of the EColG waves and decrease of the frequency (1.90 +/- 0.20 cpm) was observed. There was a significant difference between the colonic wave frequency and the frequency of the gastric waves (3.96 +/- 0.28 cpm). A good correlation was found between the number and frequency of the spike potentials in a group in the EColMG and the wave amplitude in the EColG. A sequence of low-frequency, high-amplitude waves (type B) characterized an activity period, while a sequence of low-amplitude, high-frequency waves (type A) corresponded to a quiescent period of the colonic motility. Thus the functional state of the colonic muscle wall could be judged by the differences in the frequency and amplitude of the EColG waves.