Gastric influences on canine small intestinal myoelectric activity

Enterohepatic circulation is essential for regular cycling of duodenal migrating motor complexes in dogs

The role of enterohepatic circulation and specific bile acids in the initiation and caudad migration of duodenal migrating motor complexes (MMCs) was investigated in conscious dogs. All dogs had spontaneous duodenal MMCs that migrated to the terminal ileum when bile flow was intact. During the first 3 days after total external biliary diversion, no MMCs originated in the duodenum. Instead, all MMCs originated in the jejunum and migrated to the ileum. During the next 4 days of total external biliary diversion, 81% of the MMCs originated in the jejunum and 19% in the duodenum. When normal bile flow was restored after 9 days of total external biliary diversion, regular duodenal MMCs resumed after a delay of 126 +/- 27 minutes. Perfusion of individual bile acids or dogs' own bile, but not saline or alkaline solution, into the duodenum or perfusion of dogs' own bile directly into the ileum during total external biliary diversion restarted duodenal MMCs with a time lag of about 2 hours. The authors conclude that intact enterohepatic circulation is essential for the initiation of regular duodenal MMCs.

Manometric evaluation of jejunal limb after total gastrectomy and Roux-Orr anastomosis for gastric cancer

Total gastrectomy with Roux-Orr anastomosis is frequently performed for gastric cancer. Since intestinal motility of the Roux limb has never been evaluated after this operation, pressure activity was investigated in the Roux limb of ten patients (aged 51-77 years) who had undergone total gastrectomy and Roux-Orr reconstruction. Investigations were carried out during a 6-h fast and 3 h after a 605 kcal mixed meal. During fasting only two patients had activity fronts and these were abnormal. All ten patients displayed non-propagating bursts of contractions and three had discrete clustered contractions and high amplitude jejunal contractions. The fed state was characterized by a severely reduced motor activity pattern and other abnormalities. Total gastrectomy with Roux-Orr anastomoses provokes a relatively severe disturbance in intestinal activity.

Gastrointestinal motor patterns: motilin as a coordinating factor

Our aim was to further define the role of neural and hormonal control of upper gastrointestinal motility patterns. In five dogs, the stomach and duodenum were separated enterically by transecting and oversewing the proximal duodenum and by anastomosing a Roux-en-Y jejunal limb to the pylorus. Five intact dogs served as controls. After recovery, motility was recorded on four or more occasions during fasting and after feeding. Plasma was sampled for motilin radioimmunoassay. In three Roux-en-Y dogs, motilin (0.1 microgram/kg iv) was administered. We found in the Roux-en-Y group that the characteristic MMC occurred in the stomach, duodenum, and jejunal limb, but the jejunal MMC had a much shorter period (P less than 0.005). Gastric and duodenal MMCs were coordinated temporally and were associated with peaks in plasma motilin concentration. Jejunal MMCs had no apparent association with plasma motilin. Feeding disrupted the gastric and duodenal MMC and decreased plasma motilin, but inhibited the jejunal MMC in only 6 of 12 experiments. Exogenous motilin induced a "premature" MMC in the stomach, duodenum, and jejunum. This study suggests that (1) enteric neural continuity and/or luminal continuity are not necessary for coordination of gastric and duodenal motor patterns, and (2) post-prandial inhibition of the duodenal MMC may not depend on the presence of ingested nutrient in the duodenum. Hormonal factors, possibly motilin, may play a role in initiation and coordination of gastric and duodenal motor patterns.

Role of pylorus in the control of the canine migrating motor complex

The cyclic myoelectric activity of the gastroduodenal area and the antral mucosal ionic permeability, measured by the transmural potential difference, were simultaneously evaluated in the dog. These parameters were recorded before and after section of the omental attachments to the pyloric area, section of the terminal antrum, and excision of a 2-cm segment at the pylorus. None of the surgical procedures modified the duration of the postprandial disruption of the migrating motor complexes, whereas the potential difference was increased. In fasted dogs resection of the omentum increased the migrating motor complex intervals and the duration of the phase of regular spiking activity; however, the regular spiking activities still occurred in a sequential manner. Transection of the terminal antrum was associated with a decrease in duration of the regular spiking activity phases that started simultaneously on the antrum and duodenum, without changes in the migrating motor complex intervals, and prevented the occurrence of the increase in potential difference associated with feeding. After pylorectomy, the migrating motor complex intervals were reduced by 46% on both antrum and duodenum. Our observation that only pylorectomy was able to consistently increase the frequency of migrating motor complexes suggests a pyloric inhibition of the normal pacing of the cyclic motor events at both antral and duodenal levels.

Total gastrectomy for benign disease

Among 37 patients who underwent total gastrectomy for nonmalignant disease, operative mortality was 4 per cent after 27 elective operations and 10 per cent after 10 emergency operations. Three other patients died 1 to 6 months after operation. Major postoperative complications occurred in 24 per cent. Long-term follow-up of 26 patients (81 per cent of survivors) after a mean +/- SEM of 8.4 +/- 1.1 years showed that 73 per cent of patients had no or only occasional, easily controlled, mild abdominal symptoms and good enough health to enable them to work or carry out normal activities for their age. The patients lost a mean of 15 per cent of their body weight, however, and about one third of them had weakness and diarrhea. A quarter of them had anemia despite iron and vitamin B12 therapy. Our conclusion was that total gastrectomy is a reasonable operation for benign diseases. Nonetheless, in view of the substantial postoperative mortality and morbidity, the operation should be used only when less extensive operations will not suffice.

Differential sensitivities of morphine and motilin to initiate migrating motor complex in isolated intestinal segments. Regeneration of intrinsic nerves

The effect of morphine and motilin on surgically isolated segments of small intestine was studied in 8 dogs. In 4 dogs, the small intestine was divided into four segments by simple transection and reanastomosis (group 1); in 4 others, a 2-4-cm colonic segment was interposed at each of the transection sites (group 2). The migrating motor complex initially cycled independently in each segment in group 1 dogs; after that the migration of the migrating motor complex across transection and reanastomosis began to recover and the recovery was complete 100 days after surgery. In contrast, in group 2 dogs the migration of the migrating motor complex from one segment to the next did not recover even 180 days after surgery. Morphine bolus or infusion initiated premature phase III activity in all segments but the sensitivity to morphine decreased distally. Motilin bolus or infusion initiated premature phase III activity only in the first three segments. The sensitivity to motilin also decreased distally. We concluded that (a) the interposition of a foreign segment severely impedes or prevents the regeneration of enteric nerves; (b) the sensitivity of morphine and motilin in initiating premature phase III activity decreases distally in small intestine; and (c) motilin does not initiate premature phase III activity in the ileum, but morphine may initiate premature phase III activity at all sites in the small intestine.