Preservation and propagation of cyclic myoelectric activity after feeding in rat small intestine

The cyclic nature and distal propagation of the fasting migrating motor complex (MMC) of the small intestine have been well described. The fate of the MMC after feeding, however, has not been elucidated. We used time series analysis with fast Fourier transforms (FFT) to study myoelectric cycling before and after feeding. Ten rats were chronically prepared with bipolar electrodes secured to the duodenum and proximal jejunum. Spikeburst frequency was recorded before and after feeding simple nutrients. During fasting, cyclic activity occurred at the MMC frequency. Although after feeding this periodicity appeared disrupted, FFT analysis showed persistent cycling at the fasted (MMC) rate. Digital filtering of data at the MMC frequency isolated cycling from background noise during both fasted and fed states and showed a depression in the amplitude of the waveform after feeding. Root-mean-square analysis of the waveform confirmed statistically significant depression of amplitude by 47-57%. The waveform propagated from the duodenum to the jejunum during both the fasted and fed state at an unchanged rate. We conclude that factors controlling myoelectric cycling during the fasted state persist after feeding, allowing continued net aborad propulsion of food.