The Rectal Motor Complex

To identify patterns of motility in the rectum of humans during the day while awake and at night during sleep, and to correlate the patterns with interdigestive duodenal motor complexes and sleep cycles, intraluminal rectal pressure was recorded in 12 healthy subjects (five female, seven male; mean age, 28 years) using a flexible, noncompliant, silastic catheter and an Arndorfer system with a single perfused rectal port 6 cm above the anorectal junction, duodenal motility was recorded via a perfused oroduodenal tube, and sleep stages were determined electroencephalographically. Discrete bursts of rectal motor waves, called rectal motor complexes (RMCs), were identified on 72 occasions in 11 of the 12 subjects during 157 hours of recording. The RMCs were found in daytime during fasting or after feeding (0.2 ± 0.1 RMCs/hour), but were more easily and frequently identified at night during sleep (0.8 RMCs/hour, p < .01). The complexes had a distinct onset, a mean duration ± SEM of 9.5 ± 1.0 minutes, and a distinct decline. Within each complex, the waves had a mean frequency of 3.8 ± 0.3 per minute and a mean amplitude of 19 ± 2.7 mm Hg. Complex-to-complex intervals at night averaged 74 ± 15 minutes. No clear-cut temporal association was present between the complexes and phase III of interdigestive duodenal motor complex or the REM stage of sleep.     

Gastric myoelectrical and antroduodenal motor activity in patients with achalasia

Achalasia is a primary motor disorder of the oesophagus, in which the myenteric plexus is involved. However, abnormalities in other parts of the digestive tract have also been described in achalasia. Whether gastric myoelectrical and duodenal motor activity in these patients is also affected is unknown. Therefore, interdigestive and postprandial gastric myoelectrical and antroduodenal motor activity were studied in 11 patients with achalasia, using electrogastrography (EGG) and stationary antroduodenal manometry.
Electrogastrographically, no differences were found in the gastric frequency, incidence of dysrhythmias and postprandial/fasting power ratio. In the interdigestive state a lower propagation velocity of phase III episodes was found in the achalasia patients, but other parameters were unaltered. Postprandially, no differences were found in the number of pressure waves, in the amplitude of pressure waves or in antro-duodenal coordination.
We conclude that gastric myoelectrical activity and antral motor activity in patients with achalasia is normal, suggesting an intact extrinsic and intrinsic neural innervation of the distal stomach. Although postprandial duodenal motility is normal, a lower propagation velocity of phase III suggests involvement of the small intestine in achalasia.     

Coordination of biliary and upper gastrointestinal motility in the fasted conscious pig

Abstract A chronic pig model was developed which permits the simultaneous measurement of integrated biliary motility as resistance to flow (CBD inflow), gallbladder, duodenal and gastric motility in addition to collection of venous blood samples for gut hormones estimations. Animals displayed a duodenal interdigestive cycle of 55.4 ± 3.4 min (mean ± SEM, n = 6), consisting of phase I, II and III (21.2 ± 2.1, 70.5 ± 2.0, 8.7 ± 0.5% of the cycle, respectively). A gastric inter-digestive cycle of 60.2 ± 6.5 min (n = 4) was similarly demonstrated consisting of three phases which corresponded to the three duodenal phases. The gastric phases I, II and III comprised 26.3 ± 3.0, 71.2 ± 2.7 and 2.5 ± 0.8% of the cycle, respectively. The gastric phase III immediately preceded the onset of the duodenal phase III. The gallbladder likewise displayed an interdigestive cycle of 54.5 ± 7.2 min (n = 6) consisting of a quiescent period (37.2 ± 3.7% of the cycle) corresponding temporally to duodenal phase III and phase I. This quiescent phase was followed by a period of rhythmic contractions (64.5 ± 4.1% of the cycle) which corresponded temporally to duodenal phase II. The onset of the gallbladder quiescent period coincided with the onset of duodenal phase III. The CBD inflow similarly demonstrated an interdigestive cycle of 53.4 ± 9.6 min (n = 4) duration, consisting of three phases. The initial phase was evident as a period of rapid inflow, the onset of which coincided with the onset of duodenal phase III and the gallbladder quies-centperiod, andoccupied 12.0 ± 0.8% of the cycle. The secondphase which occupied 18.0 ± 7.4% of the cycle, was typified as a period of declining inflow which reached a relatively stable level at a time corresponding to the end of duodenal phase I. The third phase consisted of the maintenance of the inflow rate achieved at the end of the previous phase (60% of maximum inflow), corresponding in onset and duration with duodenal phase II and occupied 70.0 ± 8.6% of the cycle. Plasma motilin levels fluctuated in relation to the duodenal interdigestive cycle, peaking during phase III relative to phase I (36.9 ± 8.5 vs 25.4 ± 7.7 pg mL^?1, respectively, n = 5, P < 0.05). Cholecystokinin levels did not fluctuate, remaining low (2.3 ± 2.1 pM cholecystokinin octapeptide equivalents, n = 5) throughout the duodenal interdigestive cycle, but increased about two fold after ingestion of solid food. Feeding disrupted the gastric, duodenal, gallbladder and CBD inflow cycles.     

Ileal manometry in children following ileostomies and pull-through operations

Our aim was to analyse the patterns of ileal contractions in children. We reviewed the charts of 23 children who had ileal manometry studies (16 males), mean age 7 years (range 2 months to 17 years). We positioned the manometry catheters with 4-8 recording sites, 5 or 15 cm apart, through ileostomies fashioned for clinically indicated reasons. We studied six additional children with persistent faecal soiling following endorectal pull through for Hirschsprung's disease; the catheters were positioned through the anus and colon into the ileum. We recorded phasic and tonic intermittent contractions in all the subjects, clustered contractions (rate 5-9 min-1, duration 20-120 s) in 19 subjects with ileostomies and four with endorectal pull throughs. In 13 children there were prolonged propagated contractions, > 60 mmHg in amplitude, > 15 s in duration, propagating at rates of 2-6 cm s-1 over at least 20 cm. The migrating motor complex was rare; in 55 h of fasting recording there were two phase III sequences. There are four distinctive features of ileal manometry recordings in children: random intermittent contractions, clustered contractions, prolonged propagated contractions and tonic contractions. The features of ileal motility differ from motility in the proximal small bowel.     

Phase III of the migrating motor complex: associated with endogenous xenin plasma peaks and induced by exogenous xenin

Xenin, a recently discovered peptide produced by specific endocrine cells of the duodenal mucosa, has shown exocrine, endocrine and motility effects in the gastroenteropancreatic system in animal experiments. The aim of the present investigation was to study the role of xenin in the regulation of duodenojejunal motility of humans. Twenty-nine healthy volunteers from the hospital staff gave informed consent to participate in this investigation. In 20 volunteers, we determined plasma concentrations of immunoreactive xenin at 15 min intervals over a mean time period of 8 h fasting and recorded the interdigestive motor activity of the duodenojejunum. In a double-blind randomized crossover study on other nine subjects, synthetic xenin in a dose of 4 pmol kg-1 min-1 or placebo was infused for 10 min intravenously in the interdigestive period and postprandially after a liquid meal. Duodenojejunal motility was recorded simultaneously. Predefined interdigestive xenin plasma peaks were found to be significantly associated with the phases III of the migrating motor complex. In the interdigestive period, xenin induced a premature phase III activity in each volunteer; this was followed by a second phase III in five out of nine subjects. In the postprandial state, xenin significantly increased contraction frequency and the percentage of aborally propagated contractions. These findings suggest a role of the peptide hormone xenin in modulating interdigestive and postprandial duodenojejunal motility in humans.     

Sham feeding disrupts phase III of the duodenal migrating motor complex in humans

The role of the vagus nerve in the control of the intestinal migrating motor complex (MMC) is unclear. This study aimed to evaluate the effect of physiological vagal stimulation with sham feeding on phase III of the MMC. Antroduodenal motility was recorded in six healthy volunteers. The first phase III was used as a control, and sham feeding was performed during the second phase III. The MMC was disrupted within 1.5 ± 0.4 min of sham feeding and its duration was shorter than the control phase III. Phase III propagation was inhibited in all subjects, most of them exhibiting no propagation beyond the third duodenal recording site. During sham feeding, the antrum exhibited transient phasic contractions in five out of six subjects. The duodenal motility index recorded for up to 30 min after the onset of the sham feeding was unchanged in five out of six subjects. We conclude that sham feeding consistently interrupted phase III of the duodenal MMC and induced antral contractions, but failed to provoke significant motor events in the duodenum.     

Twenty-four hour ambulatory antroduodenal manometry in normal subjects (co-operative study)

Circadian antroduodenal motor activity was studied in 40 normal subjects by means of a portable recording system consisting of a computerized data logger and a probe with microtransducers. The quantitative and qualitative characteristics of contraction events during the interdigestive and digestive periods, as well as during the awake and asleep periods, were analysed. The composition and timing of meals and night recumbence were standardized. In spite of the high interindividual variability in motor parameters, significant differences in the characteristics of interdigestive and digestive periods between waking and sleep states were found. This paper confirms the existence of a circadian variation in antroduodenal motor activity and provides reference values from a large series of normal subjects that can be used for statistical comparisons with those obtained from patients recorded with the same method.     

Validation of antroduodenal motility measurements made by echo-planar magnetic resonance imaging

Echo planar imaging, a development of magnetic resonance imaging, can produce snapshot images of the stomach and antroduodenal segment in as little as 64 msec and can be more useful than conventional techniques when assessing motility. The aim of this study was to compare antroduodenal motility measured by simultaneous perfused tube manometry and echo planar imaging. Ten volunteers were studied following the ingestion of 500 mL water or 500 mL porridge. Antroduodenal images, with acquisition times of 130 msec, were taken at 3-sec intervals, synchronized with motility traces and presented as a split-screen video. This allowed direct visual comparison of gastric wall movement and motility to be made. Contractions were confined to either the stomach or the duodenum or propagated across the antroduodenal segment. Over 4550 images were available for analysis. A larger number of propagated contractions were recorded with echo planar imaging in both water (P = 0.03) and food (P = 0.02) groups, whereas manometry detected a greater number of isolated duodenal pressure waves (P = 0.005). The contraction rate for water and food studies was similar, but direct visualization indicated that the manometric technique under-detected propagated events. The ability of echo planar imaging to record antroduodenal contractile activity provides a new insight into the role of occlusive and nonocclusive contractions during gastric emptying.     

Postnatal Maturation of Small Intestinal Motility in Preterm and Term Infants

Perfusion manometry was used to study the maturation of small intestinal motility in 15 preterm and term infants before the initiation of enteral feeding (study 1); seven of the 11 preterm infants were restudied after 3 weeks or more of enteral feeding (study 2). During study 1, the interdigestive motility of the four term infants exhibited cycles of quiescence and rhythmic activity, compatible with migrating motor complexes observed regularly in adults; in response to feeding, motility changed to irregular, phasic activity. Preterm infants, however, showed only unorganized clusters of phasic activity during fasting, and there was no consistent pattern of motor response to feeding. After 3 or more weeks of enteral feeding, interdigestive cycles with migratory motor complexes and a consistent, obvious motor response to feeding were present. Preterm infants as young as 32 weeks' gestation showed "mature" motor patterns in study 2, results suggesting that intestinal motility matures with postconceptual age.     

High-resolution analysis of the duodenal interdigestive phase III in humans

To study the spatial organization of the propagating pressure waves of duodenal phase III, we performed fasting antroduodenal high-resolution manometry with a 16-channel catheter in 12 healthy subjects. The phase III pressure waves diverged in an anterograde and retrograde direction from the start site of each pressure wave. The pressure waves maintained this configuration as the activity front moved distally in the duodenum. The start site of the pressure waves moved gradually to a point approximately 12 cm (median) distal to the pylorus and remained at this point for about 40% of the phase III time before moving further distally. The length of retrograde pressure wave propagation increased to 6 cm (median) as the pressure wave origin moved aborally to a point 10-14 cm distal to the pylorus, and then decreased when the origin of pressure waves reached the distal end of the duodenum. Bidirectional pressure waves dominated in both retrograde and anterograde activity fronts. Three pressure-wave mechanisms behind the duodenal phase IV were observed. Isolated pyloric pressure waves were absent during late duodenal phase III retroperistalsis. Thus, a number of new features of the duodenal phase III-related motility were observed using high-temporospatial resolution recordings.     

Studies of Small Intestinal Myoelectrical Activity and Intraluminal Pressure Changes in the Unrestrained Conscious Rat

Our aim was to develop and validate a methodology to permit chronic recordings of small intestinal intraluminal pressure changes in the conscious rat and thereby to study regional variations in motor activity. A low-flow (0.014 cc/min) perfusion system permitted reliable intraluminal pressure recordings at four sites along the small intestine from unrestrained animals. Comparison of overall patterns of fasted and fed motor activity and the various parameters of the migrating motor complex (MMC) from these recordings with those obtained from another group of animals prepared with serosal electrodes provided similar results in the proximal small intestine (MMC frequency 3.4 ± 0.5 vs. 3.9 ± 0.3 cycles/h, phase II duration 3.8 ± 0.7 vs. 4.7 ± 0.4 min, and phase III duration 4.0 ± 0.2 vs. 3.5 ± 0.2 min for duodenal catheters vs. electrodes, all NS). However, the distal deal phase II was considerably shorter in catheter than electrode recordings (6.0 ± 0.8 vs. 15.7 ± 2.4 min, p < 0.0001). Both methodologies confirmed significant regional variations in small intestinal motor parameters: the incidence of interdigestive myoelectrical complex (IDMEC) cycles was lower and phase II of the IDMEC was considerably prolonged in the distal Hewn. In summary, a system to permit chronic recordings of small intestinal intraluminal pressure has been developed and validated by comparison to myoelectrical recordings. Motor specialization was evident in the rat distal ileum.     

Manometric artefacts suggesting compression of the duodenum by the superior mesenteric artery in healthy humans

Multi-channel manometry offers the opportunity to study intestinal motor activity with high spatiotemporal resolution. We report tonic and phasic intraluminal pressure changes in the mid-portion of the horizontal part of the duodenum. In 10 healthy volunteers, we recorded 2 h of interdigestive duodenal motility using a water-perfused catheter. The assembly incorporated 12 duodenal sideholes at 1.5-cm intervals (D1-D12). Measurement of the antral and duodenal transmucosal potential difference (TMPD) was used to maintain a correct position of the catheter. The incidence of pressure waves (PWs) increased gradually from proximal (D1) to distal (D12) (P < 0.0001), while the mean amplitude of PWs decreased (P < 0.0001). In eight of 10 subjects, the signals recorded from D9 showed tonic pressure elevations with superimposed phasic pressure changes at heart-rate frequency, comprising 13.8% of total recording time. In the other two subjects, this phenomenon occurred in D8 (9.9% of time). D10 showed a lower incidence of PWs compared with neighbouring sideholes (D6-D9/D11-D12) (P < 0.035), with normal amplitudes. Fluoroscopy was performed in three subjects and showed that D9 was located at the midline. In healthy subjects manometric signals recorded from the horizontal part of the duodenum showed localized artefacts, presumably caused by compression by the superior mesenteric artery. In addition, a 'silent' region was present just distal to this site, the origin of which is uncertain.     

Postprandial peristalsis in the human duodenum

MMC-related retroperistalsis is a cyclical phenomenon in the duodenum linked to phase III. The aim of this study was to elucidate the direction of propagation of juxtapyloric duodenal pressure waves in the postprandial state in healthy humans and to compare with the contractions in the interdigestive phase II. Antroduodenal manometry was performed in 11 healthy subjects. Individual pressure waves propagating along a 6-cm duodenal segment were analysed with respect to the proportions of antegrade and retrograde propagation in the four duodenal subsegments (D1–D2) to (D4–D5), each subsegment being 15 mm. A test meal was given 30 min after a phase III had passed and motility recording continued for 60 min after the meal. During both the first and the second 30-min period of postprandial recording the proportion of retrograde pressure waves was larger just distal to the pylorus, (D1–D2), 40% (23–68) and 50% (23–68), respectively, compared to the distal part, (D4–D5), of the duodenal segment, 29% (12–30) and 10%(10–24), respectively (P < 0.05 and 0.01). In contrast, during late phase II of the interdigestive state antegrade pressure waves predominated in all four duodenal subsegments. We conclude that in the postprandial state a high proportion of the duodenal pressure waves (40–50%) is retrograde in the immediate juxtapyloric area while antegrade contractions predominate at a distance 5–6 cm distal to the pylorus. These manometric data together with recent observations of postprandial transpyloric liquid flow, indicate that retrograde duodenogastric propelling of contents may be an important determinant for the gastric emptying rate.     

Independent cycles of exocrine pancreatic secretion, hormones and gastroduodenal motility in healthy fasting humans: reassessment of a complex partnership

Background: interdigestive pancreatic secretion cycles in close association with the phases of the migrating motor complex (MMC) and release of regulatory hormones. The extrinsically denervated pancreas exhibits an intrinsic cyclic rhythm. We hypothesized that this intrinsic rhythm is normally present in the intact human pancreas. Methods: 19 healthy males (age range 26–35 years) were studied after 12 h fasting. A manometry catheter was positioned with four pressure ports in the antrum and three in the duodenum, and motility was recorded for a complete MMC cycle or 5 h. Duodenal aspirates were sampled at 15-min intervals, and immediately analysed for amylase, lipase and chymotrypsin activities; enzyme outputs were calculated by standard marker perfusion techniques. Plasma levels of pancreatic polypeptide (PP) and motilin were also determined (RIA) at 15-min intervals. Results: output of amylase, lipase and chymotrypsin occurred in parallel. All phase III motility fronts were accompanied by a pancreatic secretory peak. However, in 12 subjects at least one secretory peak was observed without the concomitant occurrence of phase III. A total of 16 out of 51 secretory peaks identified across all subjects were independent (31%). These phase III-independent peaks of pancreatic secretion occurred in subjects with a longer MMC cycle (160 ± 19 min vs 102 ± 13 min, P < 0.05). Phase III-associated and -independent peaks had a similar magnitude (amylase output: 21.6 ± 3.9 kU h⁻¹ vs 21.1 ± 2.8 kU h⁻¹, respectively). Irrespective of MMC phases, antral but not duodenal motor activity was closely correlated with fluctuations of pancreatic secretion (P < 0.05). Cycling of PP and motilin were also closely coordinated with pancreatic enzymes, with a particularly tight link between endocrine and exocrine secretion from the pancreas. Conclusions: peaks of pancreatic secretion invariably occur when a phase III motor activity occurs, but additional secretory peaks occur without a concomitant phase III. Interdigestive phasic pancreatic secretion is tightly coordinated with PP and motilin release as well as with antral motor activity. An intrinsic rhythm of the pancreas distinct from other cyclic activity may be present in healthy humans, expressed as peaks of pancreatic secretion independent of a motor phase III.     

Comparative analysis of phase III migrating motor complexes in stomach and small bowel using wireless motility capsule and antroduodenal manometry

Background Assessment of phase III MMC is often not performed due to the invasive nature of antroduodenal manometry used to detect it. The aim of the study was to evaluate the ability of wireless motility capsule (WMC) to detect phase III MMC and correlate it with the simultaneous measurements by antroduodenal manometry (ADM). Methods Eighteen patients underwent simultaneous ADM and WMC. MMCs were identified first on ADM and then correlated with WMC events occurring simultaneously. Frequency of contractions per min, AUC, MI, and criteria for amplitude thresholds of contractions representing MCCs on WMC tracings were defined. Key Results In 18 patients, a total of 29 MMCs were recorded by ADM. WMC detected 86% of MMC events measured by ADM. Hundred percent (10/10) of MMCs in stomach were detected by WMC, whereas 79% (15/19) of MMCs were detected in SB. The sensitivity and specificity of WMC high amplitude contractions to represent phase III MMC were 90% and 71.8% in the stomach; 73.7% and 84.7% in SB, respectively, and negative predictive value was 99.9% in both regions. Conclusions & Inferences Wireless motility capsule was able to detect the phase III MMCs as the high amplitude contractions with good fidelity. WMC does not detect the propagation of MMC. Using the pressure thresholds, WMC can detect high amplitude contraction representing phase III MMC with favorable sensitivity/specificity profile and 99.9% negative predictive value. This observation may have clinical significance, as the absence of high amplitude contractions recorded by WMC during fasting state suggests absence of MMCs.     

Acute intraduodenal bile salt depletion leads to strong gallbladder contraction, altered antroduodenal motility and high plasma motilin levels in humans.

Cholecystokinin is the main hormone involved in postprandial gallbladder contraction. There is also considerable gallbladder contraction in the fasting state, associated with phase III of the gastrointestinal migrating motor complex and release of the hormone motilin. It has been proposed that intraduodenal bile salts exert a negative-feedback control on postprandial cholecystokinin release and resulting gallbladder contraction. We wanted to elucidate whether a similar control mechanism on gallbladder contraction exists in the fasting state. We therefore performed gallbladder ultrasonography and 24-h antroduodenal motility registrations and determined plasma cholecystokinin and motilin levels in six healthy subjects before and after acute (4 g) and chronic (8 days; 8 g day(-1)) oral cholestyramine. Acute cholestyramine strongly decreased gallbladder volumes and increased motilin without changed cholecystokinin levels. There was a negative relationship between gallbladder volumes and plasma motilin levels. Although there was a persistent fasting pattern of antroduodenal motility, its cycle length was increased (P < 0.03) with markedly longer phase II (P < 0. 005). Fasting gallbladder volumes 24 h later were still strongly decreased but gradually increased to pretreatment levels. Before and after 8 days cholestyramine, interdigestive and postprandial gallbladder emptying, intestinal migrating motor complex and hormone levels did not differ. We conclude that acute (but not chronic) intraduodenal bile salt depletion with cholestyramine affects gallbladder and antroduodenal motility, possibly partly related to motilin release.     

Day‐to‐day reproducibility of prolonged ambulatory colonic manometry in healthy subjects

Background Although colonic manometry provides useful information regarding colonic physiology, considerable variability has been reported both for regional motility and manometric patterns. Whether colonic manometry is reproducible is not known. Methods Seven healthy volunteers (three men, four women, mean age = 34 years) underwent two studies of 24‐h ambulatory colonic manometry, each 2 weeks apart. Manometry was performed by placing a six‐sensor solid‐state probe, up to the hepatic flexure and anchored to colonic mucosa. Colonic motility was assessed by the number and area‐under‐curve (AUC) of pressure waves and motility patterns such as high‐amplitude propagating contractions (HAPC). Waking and meal‐induced gastrocolonic responses were also assessed. Paired t‐test was used to examine the reproducibility and intra and interindividual variability. Key Results The number of pressure waves and propagating pressure waves and HAPC, and AUC were similar between the two studies. Diurnal variation, waking and meal‐induced gastrocolonic responses were also reproducible. There was some variability in the incidence of individual colonic motor patterns. Conclusions & Inferences Colonic manometry findings were generally reproducible, particularly for the assessment of key physiologic changes, such as meal‐induced gastrocolonic, HAPC, and waking responses.     

Effects of duodenal flow on interdigestive patterns of small bowel myoelectric activity

Factors regulating the conversion of the interdigestive migrating motor complex (MMC) to postprandial patterns of motility are not completely understood. This study assessed the effects of varying rates of nonnutrient duodenal flow on patterns of interdigestive motility before and after abdominal vagotomy. Six neurally intact dogs were prepared with serosal intestinal electrodes and a duodenal infusion catheter. After recovery, the dogs were studied by infusing an isosmolar, noncaloric, balanced electrolyte solution at rates of 0, 3, 6, 9, or 12 ml/min for 5 hours into the proximal duodenum. With increasing rates of duodenal infusion, the duration of phase I decreased progressively (P < 0.05), while the period of the MMC remained unchanged. The MMC was eventually inhibited at rates of 9 or 12 ml/min with establishment of a pattern of intermittent spike activity. These findings were similar in 3 of these dogs after transthoracic total abdominal vagotomy. Our findings suggest that increases in duodenal infusion rate, independent of caloric or nutrient content, modulate patterns of intestinal motility during the postprandial period; this effect does not appear to be vagally mediated.     

Ambulatory long-term jejunal manometry in diabetic patients with cardiac autonomic neuropathy

Concerning alteration of small bowel motility in diabetic patients with autonomic neuropathy controversial data were obtained with stationary manometry and over a limited period of time. The aim of our study was to examine ambulatory 24 h jejunal motility in 15 diabetic patients with cardiac autonomic neuropathy compared with data obtained in 50 healthy controls. Twenty-four hour motility was recorded in the proximal jejunum with a portable datalogger and tube-mounted miniature pressure sensors. Diurnal and nocturnal fasting motility and the motor response to a standardized evening meal of 600 kcal were evaluated by visual and computer-aided analysis. The following abnormalities were found during fasting motility (n = number of patients): absence of phase III over 24 h (n = 2), retrograde migration or simultaneous occurrence of phase III (n = 5). During postprandial motility irregular bursts with tonic baseline elevation (n = 3) and contraction frequencies below the range of controls (n = 8) occurred. Furthermore patients exhibited an inversion of the normal relationship between phase I and phase II during nocturnal MMC – cycles, and discrete clustered contractions were diminished (P < 0.01) in the fasting and digestive state. All patients showed at least one abnormal manometric finding. We conclude that small bowel motility in diabetic autonomic neuropathy is characterized by disturbances in the generation and aboral migration of phase III, an altered circadian variability of the MMC cycle and by postprandial hypomotility.