Characteristics of the spike bursts of the duodenal minute rhythm in fasted and non-fasted sheep

Abstract

The ‘minute rhythm’ (MR), the common motility pattern, occurs in the small bowel, but its character has not been fully recognized. For this purpose, seven adult rams were supplied with seven bipolar electrodes attached to the pyloric (abomasal) antrum and the entire small bowel for the electromyographic recordings. The number of the spike bursts in one MR episode and the number of spikes in the given MR-spike-burst were counted. Furthermore, the duration of the overall periods of ten consecutive MR episodes, illustrating MR incidence, was calculated. In fasted and non-fasted animals, feeding shortened the MR period duration either in the duodenal bulb during phase 2a and 2b of the myoelectric complex (MMC) or in the duodenum, especially during phase 2b of the MMC. Feeding also caused the increased number of spikes in the MR-spike bursts in fasted animals. These changes were mostly denoted during phase 2b of the MMC. In non-fasted animals, the effects of feeding upon the number of the MR-related spike bursts were less pronounced. The number of the spikes in one spike burst was often greater in the duodenal bulb than in the duodenum. The results confirm the high variability of the MR and suggest that this motility pattern can finely be controlled to be well adapted to the current situation in the gut