Small Intestinal Motor Activity Research Articles

27. THE MOTOR RESPONSE OF THE SMALL INTESTINE TO MILK FEEDS IN PRETERM INFANTS

Small intestinal motor activity is characterised by a cyclical pattern of activity which is disrupted following food and is replaced by a continuous fed pattern. In the preterm infant, however, both patterns are poorly developed.

In man, only activity fronts that originate in the stomach correlate with motilin peaks.

We have tested the hypothesis that the imperfect correlation between the occurrence of plasma motilin peaks and the migrating motor complex (MMC) is related to the site of origin of the MMC. Gastric and small-intestinal motor activity was recorded manometrically in 16 normal subjects after an overnight fast. Blood samples were taken every 10 min and assayed for motilin. Fifty MMCs were recorded: 29 (58%) originated in the antrum and 21 (42%) in the small intestine. For gastric MMCs a motilin peak (45 +/- 5 pM) was found 10 min before the occurrence of the MMC in the duodenum. For intestinal MMCs no peak could be demonstrated. On an individual basis 27 of the 29 gastric activity fronts were associated with a motilin peak, versus 5 out of 21 intestinal MMCs. It is concluded that in man only gastric activity fronts are associated with plasma motilin peaks. Apparently, motilin is only involved in the regulation of the MMCs originating from the stomach.

THE ONTOGENY OF SMALL INTESTINAL MOTOR ACTIVITY

Three patterns of fasting small intestinal motor activity are found with increasing gestational maturity, disorganised, foetal, and migrating complex. These patterns are associated with development of the smooth muscle cell, enteric nerves and the humoral environment.Using constantly perfused multilumen nasojejunal catheters we have studied the development of small intestinal smooth muscle function and its control mechanisms in 12 preterm infants studied on 24 occasions between 28 and 44 weeks gestation. With increasing maturity well defined changes in motor function occur, gastric antral pressure (10-40cmH2O p<0.001), average duodenal pressure (3-15cmH2O p0.0001), propagated activity index (p<0.0001), and slow wave frequency (10.5-12.5cpm p=0.0001) all increased in a highly significant fashion. From the age of 32 weeks there was a significant increase in the presence of postprandial activity in response to enteral nutrition. This development profile was delayed in ill infants who were ventilated for RDS and received parenteral nutrition.These data suggest that initially there is maturation of the smooth muscle followed by the development of control systems by the enteric nerves and the humoral environment. Gestation, well being, and nutritional status are determinants of motor development, and a knowledge of the pattern of development and the determinants now allows prediction of the stage of motor development reached. Such information may be useful in planning the introduction of enteral feeds.

Effects of laxative and nonlaxative hydrophilic polymers on canine small intestinal motor activity.

Bulk-forming laxatives increase fecal volume and elicit aborally directed colonic motility patterns. Recently, it was demonstrated that test meals of the bulk-laxative fibers (cellulose and bran) elicited organized jejunal motor activity while nonlaxative fiber meals (guar) elicited unorganized jejunal motor activity. However, whether bulk-forming laxatives, as a class of compounds, differentially affect small intestinal motility has not been studied. Therefore, a study was made of the effects of the bulk laxatives psyllium and polycarbophil and the nonlaxative pectin on canine jejunal motor activity. Psyllium and pectin are examples of dietary fiber, while polycarbophil is a synthetic polymer. Pectin and psyllium test meals presented as viscous gels. In contrast, polycarbophil meals presented as a combination of discrete particles plus meal water. After each meal, measurements were made of the jejunal motility index, the time of reappearance of interdigestive burst activity, and overall motility patterns. Pectin and psyllium meals increased in viscosity as meal fiber content increased. As meal content and hence viscosity increased, both the laxative (psyllium) and nonlaxative (pectin) fiber meals elicited increasing jejunal motor activity and delays in the reappearance of the burst interval. For both fiber types, motor activity presented as randomly appearing contractions. In contrast, meals of the laxative polycarbophil elicited no more motor activity than the saline control meal. However, this control-level amount of activity presented as propagated clusters of contractions, ie, the "laxative-induced pattern." Polycarbophil did not delay the reappearance of burst activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities of interdigestive motility of the small intestine in patients with Chagas' disease

The fasting motor activity of the upper small intestine was studied in 36 patients with chronic Chagas' disease, which is known to be associated with extensive lesions of the myenteric plexuses, and the results compared with those obtained in 15 control subjects. The migrating motor complex (MMC) was detected as frequently in the Chagas' disease group as in the control group, and the frequency of contractions during the activity front was virtually the same in the two groups. In the Chagas' group the propagation of the activity fronts was slower, their duration was longer in the jejunum, but not in the duodenum, and the calculated length was shorter than normal. Chagas' disease patients without clinical manifestation or x-ray pathology of the digestive tract had no abnormalities of the MMC. These findings suggest that the intramural nervous system of the gut plays a role in the normal migration of the MMCs along the small intestine.

Patterns of small intestinal motility in duodenal ulcer patients before and after vagotomy.

Prolonged (18-24 hours) recordings of the pattern of small intestinal motor activity have been made, using radiotelemetry, in seven patients before surgery for chronic duodenal ulcer, seven after truncal vagotomy, and four with persistent post-vagotomy diarrhoea. There was no difference in the pattern of fasting cyclical activity between the three groups but the duration of feeding activity after a standard meal was reduced in asymptomatic truncal vagotomy patients compared with duodenal ulcer controls (p less than 0 . 05). In patients with post-vagotomy diarrhoea, the duration of the feeding pattern was further reduced compared with the asymptomatic post-vagotomy patients (p less than 0 . 001). It is suggested that altered emptying of food from the stomach in these patients together with duodenal receptor insensitivity is the probable explanation of these changes.

13-NLE-motilin and interdigestive motor and electrical activity of human small intestine

13-NLE-motilin and interdigestive motor and electrical activity of human small intestine

Technique for Assessment of Local Effects of Substances Found in Bile upon Opening Pressure of Choledochoduodenal Junction

An assessment of the localized influences of various chemicals found in bile was made by applying them to the interior of the canine choledochoduodenal junction. Test agents were isolated by air bubbles and introduced into the terminal lumen of the intramural portion of the common bile duct via the pressure measurement catheter; they remained in the duct for approximately 1.5min. The system was flushed and opening pressures were then measured. Responses were measured in terms of alterations in ductal opening pressures generated by a linear pressure ramp. Histamine, serotonin, and bethanechol markedly increased ductal opening pressures, whereas epinephrine and norepinephrine decreased opening pressures. None of the agents affected either cardiovascular or small intestinal motor activity in the vicinity of the sphincter when administered in this manner. The results suggest that the presence in bile of certain neurohumoral transmitters and neurohumoral‐like agents may directly affect the canine choledochoduodenal sphincter function.

Actions of Cholecystokinin and Secretin on the Motor Activity of the Small Intestine in Man

Using an intraluminal pressure recording technique, we studied the actions of cholecystokinin and secretin on the motor activity of the upper small intestine in 24 healthy subjects. We showed that the “basal” motor activity of duodenum and jejunum was stimulated by cholecystokinin (CCK). In doses of 1, 2, and 4 U per kg per hr, CCK stimulated the nonrhythmic type I waves. Secretin, on the other hand, inhibited the nonrhythmic type I and type III waves. The interactions of these two hormones showed that the CCK-stimulated upper intestinal motility was inhibited by secretin, and that the secretininhibited motility was stimulated by CCK. This study indicates that both CCK and secretin can play an important role on the autoregulation of intestinal motor function in man.

The effect of secretin and cholecystokinin-pancreozymin on the intraluminal pressure of the jejunum in the unanesthetized dog.

The effect of intravenous CCK-PZ and intravenous secretin on small intestinal motor activity was studied in 5 unanesthetized dogs. Intrajejunal pressure was recorded through a modified Mann-Bollman fistula. In ten experiments with each of two doses (0.1 units/kg and 0.4 units/kg), CCK-PZ caused a prompt and moderate increase in amplitude and rate of pressure waves. In ten experiments with each of two doses of secretin (0.25 units/kg and 1.0 units/kg), a prompt and almost complete inhibition of jejunal activity was observed.

Effects of b-diethylaminoethyl xanthene 9-carboxylate methobromide (banthine) on human gastrointestinal function.

SummaryIn 10 patients Banthine decreased the volume of gastric secretion without significantly altering gastric acidity. Gastric and small intestinal motor activity was markedly diminished in 2 studies. Banthine depressed gastric secretion in a manner similar to atropine, but side effects were less pronounced. 100 mg of Banthine produced no undesirable side effects other than dryness of the mouth.