Myoelectric activity of the stomach : gastroelectromyography and electrogastrography

The musculature of the distal two-thirds of the stomach generates electrical signals that are related, in a complex manner, to the (peristaltic) contractions of these muscles. These electrical signals originate in ion shifts from the intracellular to the extracellular space and vice-versa. Apart from recording intracellular electrical activity with the aid of a microelectrode inserted into the cell, gastric myoelectrical activity can be recorded in two ways. Firstly, gastric electrical activity can be recorded with electrodes located in the immediate proximity of the muscle layers. This method is called gastroelectromyography. lt provides information about the electrical activity of larger groups of cells. Secondly, gastric myoelectrical activity can be recorded with the aid of electrodes at relatively large distances from the stomach (e.g. on the abdominal skin). This method is called electrogastrography. It provides rather global information about the electrical activity of the stomach. Whereas the method of electrogastrography is still in a relatively early experimental phase, the method of gastroelectromyography has frequently been used in studies on gastric myoelectric activity, both in health and disease. The published descriptions of the characteristics on normal gastroelectromyographic signals are not in complete accordance, however. No agreement exists about the existence and meaning of the so-called 1 Second potential 1 (Daniel, 1965, 1966) and about the relation between intracellular and extracellular electrical activity. Furthermore, gastroelectromyographic 1 iterature paid relatively 1 ittle attention to the rhythm of the so-cal led 1 Electrical Control Activity 1 (Sarna. 1975