Migrating Myoelectrical Complex of the Small Intestine: An intrinsic activity mediated by the vagus

Abstract

In healthy conscious parenterally fed dogs and in sheep on their usual diet, the basic motor profile on the small intestine consists of recurring cycles of action potential activity. This cyclic pattern called the migrating myoelectrical complex comprises two distinct phases termed irregular, and regular spiking activity and is followed by a period of quiescence. The pattern persists after bilateral transthoracic vagotomy and in animals rendered diabetic by alloxan. In dogs, feeding disrupts the migrating myoelectrical complex pattern by obliterating the phases of regular spiking activity and quiescence for 6 to 12 hr, depending upon the amount of dry matter intake. After vagotomy a latency in the disruption of the migrating myoelectrical complex pattern with feeding occurs and in vagotomized dogs rendered diabetic, the duration of disruption is strongly reduced. In sheep, the duration of irregular spiking activity of a jejunal segment increased or decreased corresponding to the bulk of digesta, a phenomenon damped after vagotomy. The results indicate that the role of the vagus is limited to (1) prompting prandial disruption, which is then maintained by hormonal effect; (2) regulating the irregular spiking activity duration in relation to the bulk of digesta.