Influence of the interdigestive myoelectric complex on enteric flora in the rat

This study was designed to define the role of the interdigestive myoelectric complex in small intestinal bacteriostasis. In rats, six monopolar electrodes were surgically sewn to the small intestine at equal intervals. One week later myoelectric activity was recorded. Under different experimental conditions, segments of duodenum and ileum were cultured quantitatively, both aerobically and anaerobically. Five groups of 6 electrode-equipped animals each were studied after an overnight fast: rats in which (a) the interdigestive myoelectric complex was present, (b) the interdigestive myoelectric complex was disrupted for 6 h using morphine sulfate, (c) the interdigestive myoelectric complex was disrupted for 15 h using morphine sulfate, (d) the interdigestive myoelectric complex was disrupted for 15 h using phenylephrine, and (e) the interdigestive myoelectric complex returned after 15 h of morphine sulfate effect. In control rats and during baseline records before drug administration in the other four groups, the interdigestive myoelectric complex was present. Activity fronts cycled at regular intervals in the proximal small intestine and moved aborally. Activity fronts disappeared following both morphine and phenylephrine, with varying degrees of inhibition of spike activity. Titers of microorganisms increased after 6 h, becoming statistically significant at 15 h; this effect was seen with both drugs. However, titers were similar to controls in groups 5. These results show that the interdigestive myoelectric complex is an important regulator at bacterial growth in the small intestine.