The effects of varying the extent of the vagotomy on the myoelectrical and motor activity of the stomach.

The effects of varying the extent of vagotomy on the myoelectrical and motor activity of the stomach have been successfully studied in 21 patients undergoing either truncal, selective, or highly selective vagotomy for the treatment of chronic duodenal ulceration. The mean percentage time that regular antral myoelectrical activity was recorded preoperatively was 95.8% +/- 1.0 and this was decreased following highly selective vagotomy (74.0% +/- 6.6), selective vagotomy (37.8% +/- 12.4), and truncal vagotomy (30.2% +/- 10.4). The mean amplitude of the pacesetter potential was less following truncal (0.86 mV +/- 0.05), selective (1.32 mV +/- 0.09), and highly selective vagotomy (1.67 +/- 0.09) than in preoperative studies (2.21 mV +/- 0.12). Following truncal and selective vagotomies the triphasic waveform of the pacesetter potential changed to a sinusoidal shape. No significant change in the mean preoperative frequency of the myoelectrical activity (3.03 cpm +/- 0.08) occurred after vagotomy. Thus the changes in the electrical activity of the stomach are related to the extent of the vagal denervation. Intravenous administration of insulin did not alter these patterns except after highly selective vagotomy when the amplitude of the electrical waves, the incidence of action potentials, and percentage motor activity were increased.