Fasting and postprandial myoelectric spiking activity in the human sigmoid colon.

The colonic myoelectric spiking activity was recorded in 10 healthy subjects using an intraluminal tube equipped with four bipolar Ag-AgCl ring electrodes fixed 10 cm apart. The probe was introduced into the sigmoid colon by endoscopy so as to place the electrodes at 50, 40, 30, and 20 cm, respectively, from the anal verge. Recordings were performed for 2 h in the fasting state and for an additional 2 h after an 800-kcal mixed meal. The tracings showed two patterns of spiking activity. One was made of rhythmic and stationary potentials; the other was made of sporadically occurring potentials that were either propagating (at a speed of 8.4 +/- 2.5 cm/s, mean +/- SD) or nonpropagating. Food intake provoked a significant increase in both the propagating potentials (from 2.6% to 7.7% of the recording time, p less than 0.05) and the nonpropagating potentials (from 15.8% to 34.8% of the recording time, p less than 0.05). No significant change was observed for the stationary rhythmic potentials. After the meal, the sporadic nonpropagating spiking activity showed a first peak within 10-20 min and another peak within 60-70 min. Propagating spiking activity only showed one peak 70-80 min after the meal.