Effect of anthraquinone derivatives on canine and rat intestinal motility

Intraluminal pressures were measured in the gastric antrum and at different levels of the upper small intestine in 18 normal subjects to investigate whether or not the interdigestive motor complex, identified in several animal species, occurs in man and, if so, to determine its characteristics. In all normal subjects, the activity front of the interdigestive motor complex was readily identified as an uninterrupted burst of rhythmic contraction waves that progressed down the intestine and that was followed by a period of quiescence. Quantitative analysis of various parameters of the complex and simultaneous radiological and manometrical observations revealed that it resembled closely the canine interdigestive motor complex. To test the hypothesis that disorders of this motor complex may lead to bacterial overgrowth in the small intestine, similar studies were performed in 18 patients with a positive (14)CO(2) bile acid breath test and in an additional control group of 9 patients with a normal (14)CO(2) breath test. All but five patients had normal interdigestive motor complexes. The five patients in whom the motor complex was absent or greatly disordered had bacterial overgrowth as evidenced by (14)CO(2) bile acid breath tests before and after antibiotics. These studies establish the presence and define the characteristics of the normal interdigestive motor complex in man. They also suggest that bacterial overgrowth may be due to a specific motility disorder i.e., complete or almost complete absence of the interdigestive motor complex.

1. Szurszewski (1969) described a cyclic recurring, caudally migrating band of intense action potential activity, the activity fromt, in the small bowel of dogs fasted 18-21 hr. The finding has been confirmed by Carlson, Bedi & Code (1972) and by Grivel & Ruckebusch (1972). The objectives of the present study were to extend these observations first by indentifying the full sequence of myo-electric events in the stomach and small bowel of healthy conscious dogs fasted for 24-48 hr and for longer periods and second by determining the effect of ingestion of mild and of saline solution on the complex and the role of gastric distension in their action. 2. Under surgical anaesthesia, silver-silver chloride electrodes were implanted on the serosal surface of the stomach and small bowel of seven dogs, and recordings of electric activity were started when the dogs had recovered. One hundred and nine interdigestive complexes were studied in detail in five of the dogs during period ranging from 5 to 14 months. All observations were made while the dogs were healthy, conscious, and fasted. 3. The period of intense action potential activity, the activity frot or band, was found to be one phase of a cyclic-recurring sequence of changes in action potential activity. The entire sequence, composed of four phases, occured almost simultaneously in the stomach and duodenun and then migrated distally in sequence over the entire small bowel. As one cycle terminated in the distal ileum, another had started in the stomach and duodenum, and this cyclic recurrence continued during fasts of 4 and 5 days. 4. The cycles of the interdigestive complex tended to recur at the same time each day in three of the dogs. The mean periods of the cycles ranged from 90 to 114 min, and the mean time of their propagation from stomach to terminal ileim ranged from 105 to 134 min. The mean velocity of the activity fronts (phase III of the cycles) was 5-7-11-7 cm/min in the orad portion of the small bowel and 0-9-2-5 cm/min in the distal half. The mean calculated length of the activity front diminished from a range of 42-62 cm in the duodenum to 5-10 cm in the ileum. 5. Intragastric instillation of 400 ml. milk always interrupted the complex present in the bowel at the time of instillation and usually suppressed the next, whereas 400 ml. saline solution interrupted the complex present in the bowel only at the time of instillation. Distension of the stomach with a ballon always suppressed the interdigestive complex in the stomach and duodenum but sometimes failed to interrupt its migration along the bowe.