Small Intestinal Motor Activity Research Articles

Effects of metoclopramide on duodenal motility and flow events, glucose absorption, and incretin hormone release in response to intraduodenal glucose infusion

The contribution of small intestinal motor activity to nutrient absorption is poorly defined. A reduction in duodenal flow events after hyoscine butylbromide, despite no change in pressure waves, was associated with reduced secretion of the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) and a delay in glucose absorption. The aim of this study was to investigate the effect of metoclopramide on duodenal motility and flow events, incretin hormone secretion, and glucose absorption. Eight healthy volunteers (7 males and 1 female; age 29.8 ± 4.6 yr; body mass index 24.5 ± 0.9 kg/m²) were studied two times in randomized order. A combined manometry and impedance catheter was used to measure pressure waves and flow events in the same region of the duodenum simultaneously. Metoclopramide (10 mg) or control was administered intravenously as a bolus, followed by an intraduodenal glucose infusion for 60 min (3 kcal/min) incorporating the ¹⁴C-labeled glucose analog 3-O-methylglucose (3-OMG). We found that metoclopramide was associated with more duodenal pressure waves and propagated pressure sequences than control (P < 0.05 for both) during intraduodenal glucose infusion. However, the number of duodenal flow events, blood glucose concentration, and plasma 3-[¹⁴C]OMG activity did not differ between the two study days. Metoclopramide was associated with increased plasma concentrations of GLP-1 (P < 0.05) and GIP (P = 0.07) but lower plasma insulin concentrations (P < 0.05). We concluded that metoclopramide was associated with increased frequency of duodenal pressure waves but no change in duodenal flow events and glucose absorption. Furthermore, GLP-1 and GIP release increased with metoclopramide, but insulin release paradoxically decreased.

Intestinal motility and transit following chronic ingestion of different forms of palm oil diets

This study was aimed at finding the effect of palm oil diets on the small intestinal motor activity and transit in rats. Adult albino Wistar rats were divided into three groups of ten rats each. The first group was fed on rat chow containing 15% (wt/wt) of fresh palm oil diets for fifteen weeks. The second was fed on rat chow containing 15% (wt/wt) thermally oxidized diet while the third group was the control and so was fed on rat chow only. Water and feed were allowed freely to all the groups. Intestinal motility and transit were measured after the feeding period. Results show that there was a significant increase (P < 0.05) in basal tone of the ileum from rats fed on thermally oxidized palm oil diet when compared with fresh palm oil fed and control diets respectively. Contraction to acetylcholine (10(-11) - 10(-5)M) showed a biphasic tone with highest contraction at lower doses of acetylcholine and lowest tone at 10(-7)M in both fresh palm oil-fed and thermally oxidized oil-fed groups when compared with control. There was a significant (P < 0.05) attenuation of inhibition of atropine effect in the oxidized oil fed group when compared with control while there was a significant (P < 0.01) increase in transit of food material in the intestine of oxidized oil-fed group when compared with control and fresh palm oil-fed groups. These results show that chronic ingestion of oxidized palm oil diet causes an increase in basal tone of ileum and enhances intestinal motility and transit in the rat.

Effects of Physiological Hyperglycemia on Duodenal Motility and Flow Events, Glucose Absorption, and Incretin Secretion in Healthy Humans

Acute hyperglycemia slows gastric emptying, but its effects on small intestinal motor activity and glucose absorption are unknown. In type 2 diabetes, the postprandial secretion of glucose-dependent insulinotropic polypeptide (GIP) is preserved, but that of glucagon-like peptide-1 (GLP-1) is possibly reduced; whether the latter is secondary to hyperglycemia or diabetes per se is unknown. The aim was to investigate the effects of acute hyperglycemia on duodenal motility and flow events, glucose absorption, and incretin hormone secretion. Nine healthy volunteers were studied on two occasions. A combined manometry/impedance catheter was positioned in the duodenum. Blood glucose was clamped at either 9 mmol/liter (hyperglycemia) or 5 mmol/liter (euglycemia) throughout the study. Manometry and impedance recordings continued between T=-10 min and T=180 min. Between T=0 and 60 min, an intraduodenal glucose infusion was given (approximately 3 kcal/min), together with 14C-labeled 3-O-methylglucose (3-OMG) to evaluate glucose absorption. Hyperglycemia had no effect on duodenal pressure waves or flow events during the 60 min of intraduodenal glucose infusion, when compared to euglycemia. During hyperglycemia, there was an increase in plasma GIP (P<0.05) and 14C-3-OMG (P<0.05) but no effect on GLP-1 concentrations in response to the intraduodenal infusion, compared to euglycemia. Acute hyperglycemia in the physiological range has no effect on duodenal pressure waves and flow events but is associated with increased GIP secretion and rate of glucose absorption in response to intraduodenal glucose.

Patterns of Small Intestinal Motor Activity During Intraluminal Infusion of Elementary Diets in Dogs

During continuous intraintestinal infusion of elementary diets, periodic fluctuation of the frequency of contractions has been observed. This study sought to characterize the temporospatial organization of this pattern and the influence of cholinergic input. Studies were performed on unanesthetized dogs with a duodenal cannula. Motor activity was recorded by means of infused catheters and external transducers. Nutrients were infused continuously at the duodenum and jejunal levels. Studies were repeated after administration of atropine. Six to 14 periodic variations of frequency of contractions during 10 basal infusion experiments were observed in random order. During duodenal infusion, atropine significantly increased the number of these events, associated with a synchronous pattern. Frequency and amplitude of contractions during jejunal infusion were significantly lower compared to duodenal infusion. Cyclic pattern elicited by nutrient infusion is related to a cholinergic mechanism; changes depend on the level of infusion.

Rectal distension inhibits postprandial small intestinal motor activity partially via the adrenergic pathway in dogs

Objective. Rectal distension is known to induce numerous upper gastrointestinal symptoms. The aim of this study was to investigate the effects and mechanisms of rectal distension on small intestinal myoelectrical and motor activities in 8 dogs using a pair of intestinal electrodes and an intestinal fistula. Material and methods. Experiment 1 entailed a 30-min baseline recording and a 30-min recording during rectal balloon distension at various volumes (60, 80, 100 and 120 ml) randomly. Experiment 2 comprised three sessions, each including a 30-min baseline recording, a 20-min recording after intravenous infusion of saline, phentolamine (3 mg/kg) or propranolol (3 mg/kg), respectively, and another 30-min recording during rectal balloon distending. Results. 1) Rectal distension resulted in reduced intestinal motility in a dose-dependent manner (r=0.68, p<0.001). 2) The reduction in intestinal motility was significantly diminished when infusions of phentolamine (2.7±1.0 versus 8.4±1.5, p<0.01) or propranolol (3.7±1.4 versus 8.4±1.5, p<0.05) were given, suggesting partial involvement of the alpha- and beta-adrenergic pathways. 3) Rectal distension did not affect the percentage of normal 17–22 cycles/min intestinal slow waves (97.5±2.5 versus 93.0±5.3, p>0.05), or their dominant frequency (17.2±1.2 counts per minute (cpm) versus 17.7±1.0 cpm, p>0.05), or dominant power (−4.8±2.5 versus −8.2±2.9 dB, p>0.05). Conclusions. Rectal distension inhibits postprandial small intestinal motor activity in a distension volume-dependent manner in dogs, and this inhibitory effect is at least partially mediated via the alpha and beta adrenergic pathways and does not involve any alterations in intestinal slow waves.

Distal small bowel motility and lipid absorption in patients following abdominal aortic aneurysm repair surgery

To investigate distal small bowel motility and lipid absorption in patients following elective abdominal aortic aneurysm (AAA) repair surgery. Nine patients (aged 35-78 years; body mass index (BMI) range: 23-36 kg/m(2)) post-surgery for AAA repair, and seven healthy control subjects (20-50 years; BMI range: 21-29 kg/m(2)) were studied. Continuous distal small bowel manometry was performed for up to 72 h, during periods of fasting and enteral feeding (Nutrison). Recordings were analyzed for the frequency, origin, length of migration, and direction of small intestinal burst activity. Lipid absorption was assessed on the first day and the third day post surgery in a subset of patients using the (13)C-triolein-breath test, and compared with healthy controls. Subjects received a 20-min intraduodenal infusion of 50 mL liquid feed mixed with 200 microL (13)C-triolein. End-expiratory breath samples were collected for 6 h and analyzed for (13)CO(2) concentration. The frequency of burst activity in the proximal and distal small intestine was higher in patients than in healthy subjects, under both fasting and fed conditions (P<0.005). In patients there was a higher proportion of abnormally propagated bursts (71% abnormal), which began to normalize by d 3 (25% abnormal) post-surgery. Lipid absorption data was available for seven patients on d 1 and four patients on d 3 post surgery. In patients, absorption on d 1 post-surgery was half that of healthy control subjects (AUC (13)CO(2) 1323+/-244 vs 2646+/-365; P<0.05, respectively), and was reduced to the one-fifth that of healthy controls by d 3 (AUC (13)CO(2) 470+/-832 vs 2646+/-365; P<0.05, respectively). Both proximal and distal small intestinal motor activity are transiently disrupted in critically ill patients immediately after major surgery, with abnormal motility patterns extending as far as the ileum. These motor disturbances may contribute to impaired absorption of enteral nutrition, especially when intraluminal processing is necessary for efficient digestion.

Motility disorders in childhood: Working Group Report of the First World Congress of Pediatric Gastroenterology, Hepatology, and Nutrition.

Motility disorders in childhood: Working Group Report of the First World Congress of Pediatric Gastroenterology, Hepatology, and Nutrition.

Long-term treatment with cisapride and antibiotics in liver cirrhosis: effect on small intestinal motility, bacterial overgrowth, and liver function

OBJECTIVES: Altered small-bowel motility, lengthening of the orocecal transit time, and small-intestinal bacterial overgrowth have been described in patients with liver cirrhosis. These changes might be related to the progressive course and poor prognosis of the disease. We investigated the effect of a long-term treatment with cisapride and an antibiotic regimen on small-intestinal motor activity, orocecal transit time, bacterial overgrowth, and some parameters of liver function. METHODS: Thirty-four patients with liver cirrhosis of different etiology entered in the study. They were randomly allocated to receive cisapride (12), an alternating regimen of norfloxacin and neomycin (12), or placebo (10) during a period of 6 months. At entry and at 3 and 6 months, a stationary small-intestinal manometry was performed, and orocecal transit time and small-intestinal bacterial overgrowth were also investigated using the H 2 breath test. Liver function was estimated with clinical and laboratory measurements (Child-Pugh score). RESULTS: After 6 months, both cisapride and antibiotics significantly improved fasting cyclic activity, reduced the duration of orocecal transit time, and decreased small-intestinal bacterial overgrowth. Cisapride administration was followed also by an increase in the amplitude of contractions. No statistically significant variations in these parameters were observed with placebo. An improvement of liver function was observed at 3 and 6 months with both cisapride and antibiotics. CONCLUSIONS: Long-term treatment with cisapride or antibiotics reversed altered small-intestinal motility and bacterial overgrowth in patients with liver cirrhosis. These findings suggest a possible role for prokinetics and antibiotics as a modality of treatment in selected cases of decompensated cirrhosis.

Evidence that nitric oxide mechanisms regulate small intestinal motility in humans

BackgroundNon-cholinergic non-adrenergic neural mechanisms involving nerves containing NO have been shown to modulate smooth muscle in the gastrointestinal tract, and it has been suggested that release from tonic NO inhibition...

Small intestinal dysmotility following abdominal irradiation in the rat small intestine.

Abdominal symptoms such as diarrhoea, abdominal cramps and vomiting are common during and after abdominal radiotherapy for gynaecological and pelvic malignancy. It has recently been recognized that small intestinal dysmotility may contribute to these symptoms but the underlying mechanisms are unclear in part because of the technical difficulties inherent in performing studies in irradiated small intestine. The aim of the current study was to evaluate small intestinal motor activity using perfused micromanometric techniques in 6-8-cm segments of ileum during arterial perfusion with isotonic oxygenated fluorocarbon solution. Intestinal segments from six rats were studied 4 days after treatment with 10 Gy abdominal irradiation. Ileal segments from nine nonirradiated animals acted as controls. For each experiment the total number of pressure waves, high-amplitude (> 20 mmHg, long-duration > 6 sec) pressure waves, and long (> 20 associated) bursts of pressure waves were determined. Irradiation had no effect on the overall number of pressure waves, but increased high-amplitude long-duration (HALD) pressure waves (248 vs 7, P < 0.01). In control animals HALD waves were localized to a single recording site but after radiotherapy 74% of HALD waves were temporally associated with similar pressure waves in other manometric channels. Forty-seven per cent of associated HALD waves migrated aborally. Retrograde migration of HALD waves was seen in five segments following irradiation. Irradiation abolished bursts of > 20 pressure waves.

A novel portable perfused manometric system for recording of small intestinal motility.

The development of solid-state catheters with miniature pressure transducers and portable dataloggers with a large memory capacity has allowed recording of gastrointestinal motility in ambulant subjects. Developments in silicone rubber extrusion technology made it possible to build a perfused manometric system, using a perfused manometric assembly requiring a low volume of perfusate. In the present study the feasibility of recording and automated analysis of small intestinal motility using a perfused multiple lumen manometric system was evaluated in seven healthy volunteers. Pressures were recorded from 12 sideholes arranged in four clusters spaced at 10-cm intervals from the catheter tip. Each channel was perfused at 0.15 mL min-1 with degassed water by a portable, low-compliance, perfusion pump. The 12 sidehole recording channels were connected to external transducers mounted on a belt. Pressure data were stored in two dataloggers. Motility was recorded in the sitting (30 min), and supine (30 min) position, during walking (30 min) and postprandially (90 min). Using purpose-built software baseline variations were corrected for and manometric variables (number of pressure waves, mean amplitude and motility index) calculated. Bench testing of the manometric assembly showed a median baseline pressure offset of 4.2 kPa (range 3.7-10.1) and upon occlusion a rise rate of 27.8 kPa sec-1 (range 19.7-30.8). Changes in body position affected baseline pressures so that compared to the supine position changes in baseline pressure varied between 1.5 +/- 0.7 kPa and 1.9 +/- 0.6 kPa during sitting (P < 0.02), and between 1.7 +/- 0.7 kPa and 1.5 +/- 0.9 kPa during walking (P < 0.03). Manometric recordings obtained during the fasting period showed an increase in small intestinal motor activity during walking. In the postprandial period no differences in motility variables were observed within one cluster and in time. Recording of small intestinal motility with a multiple-channel silicone rubber manometric assembly with a portable perfusion system is a feasible technique which is relatively inexpensive. Computer-assisted data processing allows for adequate elimination of artefacts and automated numerical analysis.

Selective Nutrient Feeding Induces Maturation of Gastrointestinal Hormone Release in Preterm Infants • 1498

We have previously shown that preterm infants given small enteral feedings have higher plasma concentrations of gastrin and gastric inhibitory peptide(GIP), while plasma concentrations of peptide YY (PYY) are unchanged. In adults, the ingestion of protein stimulates the release of gastrin which, in turn, stimulates the release of acid and stimulates an increase in gastroduodenal motor activity. Carbohydrate stimulates the release of GIP which regulates plasma glucose and inhibits small intestinal motor activity. Fats stimulate the release of PYY which inhibits small intestinal motor activity. We speculated that feeding babies with selective nutrients would induce hormone release in preterm infants as they do in adults, and, thus, enhance gastrointestinal function. Eighty preterm infants 25 to 30 wks gestation admitted to the Newborn Intensive Care Unit at Ben Taub General Hospital were fed 24 ml/kg/d for the first 10 days they received enteral feedings in addition to parenteral nutrition. Infants were given one of 4 formulas: full 24 cal/oz formula (n=20), its carbohydrate (n=20), protein(n=20), or fat component (n=20), all fed in 4 hr cycles consisting of 2 hr infusions interrupted by 2 hrs of fasting. On the tenth study day, blood was drawn to determine fasting plasma concentrations of gastrin, GIP, and PYY. In addition, motor responses to a full strength formula feeding were assessed via a low compliance continuous perfusion manometry. Compared to values seen at birth, fasting plasma concentrations of gastrin increased by feeding day 10 among infants fed protein, fat, or full formula (all p<0.05, paired t test) but not carbohydrate. GIP plasma concentrations increased in babies fed carbohydrate or full formula (both p<0.05) but not fat or protein. Plasma concentrations of peptide YY did not change in any feeding group. No group of study infants displayed the presence of a motor response to feeding before enteral feedings were begun. Babies fed protein or full formula displayed motor responses to feeding after 10 days of feeding while babies fed carbohydrate and fat did not. We conclude that the release of gastrointestinal hormones in response to selective nutrients is present in preterm infants, as well as motor responses to feeding that are mediated by those nutrients. We speculate that designing formulas that trigger intestinal hormonal release may be useful in enhancing the infant's endogenous mechanisms to improve gastrointestinal function.

Small intestinal motility

Our understanding of small intestinal motor activity and its control pathways has advanced despite the limitations of measurement techniques and the complexities and interactive nature of small intestinal control pathways. Recent studies have used molecular biology techniques in addition to more conventional methodologies to provide new insights into the field. This review summarizes developments in this area in the past 12 months.

P-652 - Analysis of mechanism underlying benzamides-stimulated motor activity of dog small intestine by in vivo microdialysis

P-652 - Analysis of mechanism underlying benzamides-stimulated motor activity of dog small intestine by in vivo microdialysis

Effects of a selective and a nonselective muscarinic cholinergic antagonist on heart rate and intestinal motility in dogs.

The effects of methoctramine, a cardioselective muscarinic cholinergic antagonist, on heart rate and small intestinal motor activity were compared to those of the nonselective competitive muscarinic antagonist, atropine. Methoctramine or atropine, 6, 10, 30, 60 micrograms/kg, or sterile isotonic saline, was administered intravenously to six conscious dogs in cross-over studies. Methoctramine administration caused dose-dependent tachycardia without affecting intestinal motility, while atropine administration caused dose-dependent tachycardia accompanied by significant reductions in small intestinal motility. Additionally, methoctramine did not inhibit intestinal smooth muscle contractile activity initiated by the muscarinic agonist bethanechol, while atropine inhibited bethanechol-induced contractile activity in a dose-dependent manner. Calculated, dosages of methoctramine and atropine required to produce a 50% increase in heart rate over baseline were 35.1 +/- 5.3 and 39.5 +/- 6.2 micrograms/kg, respectively. This dosage of atropine caused a 93 +/- 13.9% reduction in intestinal motility. These findings suggest that selective muscarinic antagonists may be useful drugs for those veterinary patients in which nonselective muscarinic antagonists have the potential to produce untoward effects on intestinal motility.

INTESTINAL MOTILITY DURING ONTOGENY AND INTESTINAL PSEUDO-OBSTRUCTION IN CHILDREN

From the fragmentary studies performed to date of both functional obstruction and the ontogeny of intestinal motility, several conclusions can be drawn. The development of motor activity that is primarily dependent on neuronal activity, such as sucking, swallow-induced peristalsis of the esophagus, and cyclic fasting small intestinal motor activity, occurs according to a timetable that is similar in all species studies is gestationally dependent, but its timing during gestation is species specific. Postprandial events, including gastric emptying and continuous postprandial motor activity in the small intestine, in contrast seem to be dependent on the nature of the humoral response to food, provided that the musculature of the gut and enteric nerves are able to respond to it. Although these activities are primarily determined by neuronal development, there is a limited amount of information to suggest that their appearance may be pharmacologically manipulated to advance the timing and rate of development. It is commonplace now for cortisol to be used to induce the production of surfactant in mothers of babies who are at risk of hyaline membrane disease. A limited amount of information suggests that cortisol may have similar effects in inducing duodenal motor activity, and, thus, it may be possible to advance the timing and rate of development of intestinal motility in the very preterm infant by its use. There are, however, no studies to date to prove this. It is now clear that intestinal pseudo-obstruction is a heterogeneous disorder associated with various pathologies, some of which are intrinsic to the gut, whereas others are multisystem diseases affecting the intestine. In addition, although intestinal pseudo-obstruction was originally thought to involve the small intestine, it is now realized that it may not affect only one region, as in achalasia or Hirschsprung's disease, but also it may present diffusely throughout the gut. The motility changes caused by the disease processes are nonspecific, although neuropathic and myopathic changes are distinct and due to the destruction of the particular motor control system involved. The mechanisms of the ontogenic and disease changes described in this article are, however, almost totally unexplored. The recent upsurge of interest in the area with the development of advances in cellular and molecular biology, at least the early events, is now beginning to unravel. At the present time, the stage is being set for probably the most exciting phase of understanding of the nature of the ontogeny of intestinal motor activity, which the author expects will enable us to manipulate motor activity in normal preterm infants and, it is hoped, congenital dysmotile states.

Effect of casein and casein hydrolysate on small bowel motility and D-xylose absorption in dogs.

Food administration is followed by the appearance of a small intestinal pattern of irregular contractions. Studies on the relationship between intestinal motor activity, transit and absorption have yielded contradictory results. Since previous studies have shown that casein and casein hydrolysate led to a decrease of small intestinal motor activity and transit, the aim was to evaluate the effect of these nutrients on small intestinal motility and D-Xylose absorption. Studies were performed in five dogs with a duodenal fistula; motility was recorded by means of six infused catheters and external transducers. Three test solutions with the same osmolality, lactulose, casein and casein hydrolysate, were continuously infused through the duodenal cannula. D-Xylose was injected in the duodenum and plasma levels determined at regular intervals. Absorption of D-Xylose was greatest during the administration of casein hydrolysate, the lowest levels were seen with lactulose and intermediate levels were obtained with casein. The effect of casein hydrolysate on small intestinal motility was characterized by a decrease in the frequency of contractions. Propulsive contractions were decreased after the infusion of both casein and casein hydrolysate. Lactulose infusion was followed by the greatest motor activity of both frequency and propulsive contractions. These results suggest that the motor patterns observed with casein and casein hydrolysate lead to increased intestinal absorption of D-Xylose.

Effect of octreotide and erythromycin on idiopathic and scleroderma-associated intestinal pseudoobstruction.

Treatment of chronic intestinal pseudoobstruction with prokinetic agents has been disappointing. Our study was designed to determine if octreotide and erythromycin would provide sustained relief from nausea, abdominal pain, and bloating in pseudoobstruction. Using gastrointestinal manometry, quantitative parameters of the activity front of the migrating motor complex at baseline and after prokinetic therapy with erythromycin and octreotide were determined in 14 patients with intestinal pseudoobstruction who had nausea, abdominal pain, and bloating. Patients were treated with erythromycin and octreotide for 20-33 weeks. Octreotide increased the frequency, duration, and motility index of activity fronts (AFs) from 1.2 +/- 0.3 AFs/4 hr, 2.7 +/- 0.7 min, and 85 +/- 23 min mm Hg to 4.1 +/- 0.8 AFs/4 hr, 5.5 +/- 0.7 min, and 152 +/- 24 min mm Hg, respectively (P < 0.05). Antral activity was decreased from 63 +/- 14 to 23 +/- 8% by octreotide (P < 0.05). Erythromycin induced antral activity; however, small intestinal motor activity was suppressed. While on erythromycin and octreotide, five patients had long-term improvement of nausea and abdominal pain. All responders had at least 5 AFs/4 hr induced by octreotide. We conclude that octreotide and erythromycin relieve abdominal pain and nausea in pseudoobstruction. Patients who have at least 5 AFs/4 hr after octreotide administration are most likely to clinically respond.

Fractionated irradiation alters enteric neuroendocrine products.

Radiation profoundly alters the contractile activity of the small intestine and colon. We hypothesized that some motor changes of the gut might be secondary to impaired neural input to smooth muscle or abnormal release of gut endocrine peptides. The density of products within peptidergic and cholinergic nerves and gut endocrine cells was estimated in six normal controls and six dogs who had received 1500 cGy in six equal fractions of 250 cGy. Choline acetyltransferase, acetylcholinesterase, vasoactive intestinal peptide (VIP), substance P, peptide YY (PYY), and motilin were measured in tissue specimens divided into mucosal-submucosal (MS) and muscularis externa (ME) layers. Tissue samples were obtained from the duodenum, jejunum, ileum, and proximal and distal colon. In addition, serum levels of motilin and PYY were determined before and during the administration of 1500 cGy in four separate dogs instrumented to record upper gut contractile activity. Intrinsic cholinergic activity as estimated by choline acetyltransferase activity was unchanged, while acetylcholinesterase activity increased in the MS layers of distal small bowel and colon. VIP was increased in the MS layers of jejunum and proximal colon as well as in the ME layers the jejunum and ileum. By contrast, substance P increased in the jejunal and proximal colonic MS layers and in the ME layers of the jejunum and ileum. Duodenal and jejunal motilin levels markedly decreased after radiation exposure, while serum motilin levels continued to cycle at a decreased peak level with migrating motor complexes. Colonic PYY remained unchanged but serum PYY levels decreased after irradiation. Increased neuronal synthesis and inhibition of neurotransmitter release are potential explanations for elevated tissue concentrations of VIP, substance P, and acetylcholinesterase. There appeared to be differences in the sensitivity of gut endocrine cells to irradiation. Changes in gut regulatory peptides and cholinergic enzyme activity occur with fractionated doses of abdominal irradiation, while the same schedule of irradiation produces striking changes in the canine small intestinal and colonic motor activity. It is therefore likely that alterations of contractile events may be produced by changes in gut neuroendocrine products.

Intestinal manometry in man: a historical and clinical perspective.

The historical background and current status of manometry of the small intestine are reviewed. The evolution of technology for the assessment of small intestinal motor activity in man is described and advances in physiology and pathophysiology highlighted. Technological advances over the past several decades have permitted the extensive study of intestinal motility in man and have led to both a greater understanding of intestinal motor physiology and an increased awareness of the breadth of intrinsic variability. Though motor patterns have been described in various disease states, the definition of the clinical utility of intestinal manometry must await further prospective studies, which should, in particular, compare manometry with other available and less invasive tests.