Interdigestive gastric motility patterns: The role of vagal and nonvagal extrinsic innervation

Our study was designed to determine separately the roles of vagal and nonvagal extrinsic innervation in the initiation and coordination of patterns of gastric contractile activity and in the organization of the gastric slow wave. Four dogs first underwent transection of all extrinsic and intrinsic neural continuity to the stomach, except for careful preservation of vagal innervation to the stomach (stage 1). Manometry catheters and serosal electrodes were placed in the antrum, and electrodes were fixed to the small intestine. After recovery, motility was recorded during fasting and after feeding. A cyclic motor pattern occurred in the stomach with a period that was not different from that of the migrating motor complex in the small intestine (113 ± 11 minutes vs 112 ± 11 minutes; p > 0.05). Gastric and intestinal motility remained coordinated in time. Feeding inhibited this cyclic motor pattern in stomach and intestine. Antral tachygastria (slow wave frequency greater than 8 cycles/min) was infrequent (less than 1% of time). Each animal was restudied after completing extrinsic gastric denervation by a transthoracic vagotomy (stage 2). Vagotomy did not alter the presence, appearance, or period of cyclic gastric activity, nor did it disrupt temporal coordination with the duodenal migrating motor complex or increase the prevalence of tachygastria. In conclusion, neither vagal nor nonvagal extrinsic innervation to the stomach was required for initiation or coordination of the characteristic cyclic gastric motility pattern during fasting; although vagal innervation may modulate gastric myoelectric activity, its precise role is not evident in this study.