Characteristics of fasting and fed myoelectric activity in rat small intestine: evaluation by computer analysis

Evaluation of gastrointestinal myoelectric activity has been limited by the assessment techniques and the complexity of the recorded myoelectric signal. Commonly, myoelectric activity is evaluated as motor patterns, which only gives a semiquantitative measure of myoelectric events within the bowel wall. Using myoelectric recordings from the proximal small intestine in rats, a computerized system for acquisition, storage, display and calculation of characteristics for the myoelectric activity was developed. The software was tested in myoelectric recordings from nine rats in fasting and fed states. All migrating myoelectric complexes (MMCs) during fasting and fed myoelectric patterns were recognized in both digital and analog recordings. Reproduction of myoelectric recordings by the computerized system was indistinguishable from that of the analog system. Employing an appropriate cut-off trigger level and a high sampling frequency, spike potentials were recorded in the proximal jejunum with 0.4 (0.3-0.5) spikes 10 s-1 during phase 1 of MMC, 19.5 (15.1-23.9) (P < 0.001) during phase 2, and 103.8 (97.2-110.5) (P < 0.001) during phase 3. In fasted state, MMCs were most frequent in the proximal jejunum whereas fewer were found in the duodenum and distal jejunum. To achieve stable values for MMC cycle length at least four MMCs had to be calculated. After feeding in phase 1, the myoelectric activity increased to 23.8 (13.6-33.9) spikes 10 s-1 (P < 0.001), whereafter the spiking activity decreased over a period of 2 h until a fasting motor pattern was resumed. It is concluded that computerized technology enables evaluation not only of myoelectric patterns, but also of spiking activity per time unit, i.e. the intensity of myoelectric activity in the gut.