Electrical patterns in the human jejunum with and without vagotomy: migrating myoelectrical complexes and the influence of morphine

Abstract

Postprandial symptoms that occur in some patients following operation for duodenal ulcer are generally attributed to disruption of normal controlled gastric emptying resulting from vagotomy, enterostomy, or pyloroplasty. The notion that disturbances of small bowel motility could be caused by vagotomy and contribute to these symptoms led the author to examine the myoelectrical patterns of the small intestine in duodenal ulcer patients undergoing elective surgery for control of symptoms. These patients underwent either partial interruption of their vagus nerves by proximal gastric vagotomy (PGV) or complete section by truncal vagotomy (TV). Their records were compared with those of an equal number of control subjects with intact vagus nerves undergoing laparotomy for either gallstones or colonic cancer. Postoperative recordings were obtained without sedation via electrodes implanted at laparotomy and led out of the abdomen through a drain in the right upper quadrant. Observations were made on days 6 through 9 after reestablishment of normal gastrointestinal function. Three patterns of electrical activity were recorded--electrical control activity, electrical response activity, and migrating myoelectrical complexes (MMCs). No observable differences were seen among PGV, TV, and control procedure during fasting or fed conditions. A key to an understanding of the origin of the MMCs was provided by the finding of disruption of the normal cycling of the complex by a premature cycle whenever morphine was given. Release of acetylcholine in the myenteric plexus of the intestine by an intrinsic opioid agonist may be the initiating event of the intrinsic MMC. Exogenous morphine may have caused a premature MMC by mimicking the stimulus produced by endogenous opioid. The morphine response was similar in persons with or without vagus nerves, suggesting that the initiation of cycling of the complex is entirely under local control of the intestine and not exercised through the parasympathetic division of the autonomic nervous system.