Effects of rest, stress, and food on myoelectric spiking activity of left and sigmoid colon in humans

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Abstract
The great variability which is known to affect colonic motility may partly be the result of changes in physiological conditions. In order to test this hypothesis, 40 subjects were sequentially put in conditions of vigilance, rest, stress, and feeding while colonic motility was monitored. The myoelectric spiking activity of the left colon was recorded with a 50-cm-long silastic tube equipped with four bipolar ring electrodes (located 10 cm apart) introduced into the left colon by flexible sigmoidoscopy. Tracings were performed while the subjects were kept awake (by conversation) for 1 hr, put at rest (quiet) for another 1 hr, submitted to a stress (by alternatively immersing and removing one hand from 2–4‡C cold water) for 20 min, and finally recorded for 2 hr after a 800-kcal meal. In 18 other subjects, the sequences of vigilance and rest were randomized. The results showed that colonic spiking activity was made of sporadic bursts that are known to be associated with intraluminal propulsion and of stationary bursts that probably play no role in colonic peristalsis. The duration of sporadic spiking activity was respectively 13.6±1.2 min/hr (mean±sem) during the period of vigilance, 5.4±0.6 min/hr during the period of rest (P<0.001), 14.3±1.0 min/hr during the period of stress (NS), and 16.8±1.2 min/hr after a meal (P<0.05). The duration of stationary spiking activity did not change significantly throughout the four periods, respectively, 6.6±4.9, 4.4±3.7 (NS), 5.2±3.9 (NS), and 3.3±2.8 min/hr (NS). When the sequences of vigilance and of rest were randomized, sporadic spiking activity was also significantly decreased during the periods of rest. These results indicate that colonic motor activity may show considerable changes during control recordings depending on whether the subjects are in a state of vigilance or of rest.