Effect of stress, meal and neostigmine on rectosigmoid electrical control activity (ECA) in normals and in irritable bowel syndrome patients.

An intraluminal probe with two sets of bipolar electrodes (4 cm apart) was used to record electrical control activity (ECA) from the rectosigmoid of 17 normal subjects and 16 IBS patients in the resting state, during neutral and stressful interviews, and after a meal or neostigmine. Fast Fourier transform method was used for the frequency analysis of ECA. The ECA was present at all times in both the groups but was variable in frequency and amplitude and was phase-unlocked during all recording periods. Up to four frequency components were observed in the lower frequency range (LFR) of 2.0-9.0 c/min and up to two in the higher frequency range (HFR) of 9.0-13.0 c/min during all recording periods. The frequency and organization of ECA were not significantly different between the normal and the IBS groups in the resting state. Neutral and stressful interviews did not significantly affect the mean ECA frequency in either of the groups but the mean ECA frequency of the dominant frequency component in LFR was lower in IBS patients than in the normal subjects during the stressful interview. Meal and neostigmine did not significantly affect the ECA frequency or its organization in either of the groups. It appears from this study that alternations in colonic ECA may not form the basis of motility disorder in irritable bowel syndrome.