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.     

GLP-1 regulates gastroduodenal motility involving cholinergic pathways

Abstract  The gut-born incretin hormone glucagon-like peptide-1 (GLP-1) delays gastric emptying. To elucidate the mechanisms by which GLP-1 affects gastroduodenal motility and glycaemia, we studied the effects of exendin(9–39), a potent GLP-1 receptor antagonist, on gastroduodenal motility and pancreatic hormones. In this randomized, double-blind, placebo-controlled, four-arm, cross-over trial, 10 healthy volunteers were studied during the interdigestive period followed by duodenal perfusion of a mixed liquid meal (250 kcal). On four separate days, exendin(9–39), atropine, exendin(9–39) + atropine or saline were infused intravenously. Antro-pyloro-duodenal and fundic motility were assessed. The compliance of the proximal stomach was determined by isobaric distensions. During fasting, exendin(9–39) did not influence proximal gastric volume, pyloric tone, and duodenal contractility. Exendin(9–39) significantly increased antral waves only in the absence of atropine. During duodenal meal perfusion, exendin(9–39) significantly reduced proximal gastric volume accommodation, abbreviated postprandial antral inhibition, reduced the postprandial increase in pyloric tone, and reduced gastric compliance. Atropine abolished the effects of exendin(9–39) on gastric volume accommodation but did not affect its effects on postprandial antroduodenal motility and on gastric compliance. Exendin(9–39) increased fasting and postprandial glycaemia and plasma glucagon but not insulin concentrations. Atropine did not affect GLP-1 secretion. Cholinergic mechanisms mediate the effects of GLP-1 on postprandial gastric accommodation but not on antro-pyloro-duodenal motility. GLP-1 reduces fasting and postprandial glycaemia, in part by reducing glucagon secretion.     

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.     

Functional association between proximal and distal gastric motility during fasting and duodenal nutrient stimulation in humans

A functional integration exists between proximal and distal gastric motor activity in dogs but has not been demonstrated in humans. To determine the relationship between proximal and distal gastric motor activity in humans. Concurrent proximal (barostat) and distal (antro-pyloro-duodenal (APD) manometry) gastric motility were recorded in 10 healthy volunteers (28 +/- 3 years) during (i) fasting and (ii) two 60-min duodenal infusions of Ensure((R)) (1 and 2 kcal min(-1)) in random order. Proximal and APD motor activity and the association between fundic and propagated antral waves (PAWs) were determined. During fasting, 32% of fundic waves (FWs) were followed by a PAW. In a dose-dependent fashion, duodenal nutrients (i) increased proximal gastric volume, (ii) reduced fundic and antral wave (total and propagated) activity, and (iii) increased pyloric contractions. The proportion of FWs followed by a distal PAW was similar between both infusions and did not differ from fasting. During nutrient infusion, nearly all PAWs were antegrade, propagated over a shorter distance and less likely to traverse the pylorus, compared with fasting. In humans, a functional association exists between proximal and distal gastric motility during fasting and duodenal nutrient stimulation. This may have a role in optimizing intra-gastric meal distribution.     

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.     

Postprandial gastric antral contractions in patients with gastro-oesophageal reflux disease: a scintigraphic study

Abstract  Disturbed gastric contractility has been found in manometric studies in patients with gastro-oesophageal reflux disease (GORD), but the pathophysiological role of this abnormality is unclear. We aimed at assessing postprandial gastric antral contractions and its relationships with gastric emptying and gastro-oesophageal reflux in GORD patients. Fasted GORD patients ( n  = 13) and healthy volunteers ( n  = 13) ingested a liquid meal labelled with 72 MBq of ^99mTechnetium-phytate. Gastric images were acquired every 10 min for 2 h, for measuring gastric emptying half time. Dynamic antral scintigraphy (one frame per second), performed for 4 min at 30-min intervals, allowed estimation of both mean dominant frequency and amplitude of antral contractions. In GORD patients ( n  = 10), acidic reflux episodes occurring 2 h after the ingestion of the same test meal were determined by ambulatory 24-h oesophageal pH monitoring. Gastric emptying was similar in GORD patients and controls (median; range: 82 min; 58–126 vs 80 min; 44–122 min; P  = 0.38). Frequency of antral contractions was also similar in both groups (3.1 cpm; 2.8–3.6 vs 3.2 cpm; 2.4–3.8 cpm; P  = 0.15). In GORD patients, amplitude of antral contractions was significantly higher than in controls (32.7%; 17–44% vs 23.3%; 16–43%; P  = 0.01), and correlated positively with gastric emptying time ( R _s = 0.58; P  = 0.03) and inversely with the number of reflux episodes ( R _s = −0.68; P  = 0.02). Increased amplitude of postprandial gastric antral contractions in GORD may comprise a compensatory mechanism against delayed gastric emptying and a defensive factor against acidic gastro-oesophageal reflux.     

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.     

Gastric emptying and the organization of antro-duodenal pressures in the critically ill.

The motor dysfunctions underlying delayed gastric emptying (GE) in critical illness are poorly defined. Our aim was to characterize the relationship between antro-duodenal (AD) motility and GE in critically ill patients. AD pressures were recorded in 15 mechanically ventilated patients and 10 healthy volunteers for 2 h (i) during fasting, (ii) following an intragastric nutrient bolus with concurrent assessment of GE using the (13)C-octanoate breath test and (iii) during duodenal nutrient infusion. Propagated waves were characterized by length and direction of migration. Critical illness was associated with: (i) slower GE (GEC: 3.47 +/- 0.1 vs 2.99 +/- 0.2; P = 0.046), (ii) fewer antegrade (duodenal: 44%vs 83%, AD: 16%vs 83%; P < 0.001) and more retrograde (duodenal: 46%vs 12%, AD: 38%vs 4%; P < 0.001) waves, (iii) shorter wave propagation (duodenal: 4.7 +/- 0.3 vs 6.0 +/- 0.4 cm; AD: 7.7 +/- 0.6 vs 10.9 +/- 0.9 cm; P = 0.004) and (iv) a close correlation between GE with the percentage of propagated phase 3 waves that were antegrade (r = 0.914, P = 0.03) and retrograde (r = -0.95, P = 0.014). In critical illness, the organization of AD pressure waves is abnormal and associated with slow GE.     

MMC-related duodenojejunal antegrade and retrograde peristalsis in humans

Abstract According to recent manometric studies the last part of phase III of the migrating motor complex (MMC) shows the features of a retroperistaltic pump in the proximal duodenum in most healthy humans. In the present study, individual contractions in phase II and phase III of the MMC were investigated in ten healthy subjects (four males, six females), focusing on the distal duodenum and the jejunum. Motility was recorded on two different days with eight-channel catheters. On one day a standard antroduodenojejunal fasting recording was performed for 5 h, allowing detailed analysis of pressure waves in the proximal duodenum. On another day a two-station measurement was performed in the proximal jejunum and the distal duodenum. The propagated pressure waves were analysed for late phase II (last 30 min) and for the first and the last part (I min) of phase III in the three intestinal segments. Antegrade peristalsis predominated at all levels in phase II and in the first part of phase III. In contrast, 84 ± 11% of all propagated contractions were retrograde in the last part of phase III in the proximal duodenum and 75 ± 16% in the distal duodenum. The proportions of retrograde contractions in early phase III and in late phase III differed significantly, from 11 ± 11% to 84 ± 11% and from 32 ± 16% to 75 ± 16% in the proximal and distal duodenum, respectively (P < 0.01 and P < 0.05). In the proximal jejunum such retroperistalsis was not observed, neither in the beginning nor at the end of phase III. In phase II the proportions of retrograde pressure waves were small (3–10%) in the three segments studied. The migration velocity of the pressure waves showed a gradient in this phase, with the lowest values in the jejunum. It is concluded that the last part of phase III shows the pressure pattern of a retroperistaltic pump through out the duodenum. In contrast, no distinct MMC-related retroperistalsis was observed in the jejunum.     

Adrenergic Control of Interdigestive and Digestive Motility via the Pyloric Region

This study examines the influence of an α-adrenergic blocking drug, phentolamine, on inter digestive and digestive motility when given intraarterially, close to the pylorus. In seven mongrel dogs four extraluminal bipolar platinum electrodes and four strain-gauge force transducers were placed at the antrum and proximal duodenum and three mini strain gauges and one electrode at the pyloric ring. After two migrating motor complexes (MMCs) were registered the drug was applied through a catheter inserted via the arteria gastroomentalis dextra to the pylorus, during phase I, the middle and end of phase II of the MMC, and 15 to 25 minutes after a meat meal. Local α-adrenergic blockade of the pylorus caused immediate conversion of phase I to phase II of the MMC, with significant prolongation of phase II, broadening of antral and pyloric contractions, and in some animals giant contractions with vomiting and retching. The pyloric motility index in phase III increased up to 22%. It prolonged phase II by 237%. Phentolamine after the meat meal caused an increase in motility index, mainly in the pylorus, while the increase in contraction frequency was less pronounced. The results indicate inhibitory adrenergic control of the interdigestive motor pattern and digestive motility in the pyloric region.     

Central regulation of gastric emptying of solid nutrient meals by corticotropin releasing factor

Central regulation of gastric emptying of a solid nutrient meal and spatial and temporal parameters of gastro-pyloro-duodenal contractions by corticotropin-releasing factor (CRF) were investigated in conscious dogs. Intracerebroventricular (ICV) infusion of CRF at 0.033 nmol kg⁻¹ min⁻¹ for 15 min in a volume of 0.2 mL significantly delayed the total gastric emptying time of the meal. ICV infusion of CRF also increased the mean frequency of proximal duodenal contractions and decreased the percentage of distally propagating contractions in the whole duodenum. The remaining parameters of pyloric and duodenal contractions were not affected. A prior ICV infusion of I-helical CRF_9–41 (0.166 nmol kg⁻¹ min⁻¹ for 15 min in a volume of 0.2 mL) blocked the central effects of CRF on gastric emptying time and the duodenal contractions. Central infusion of CRF had no significant effect on the lag phase of gastric emptying. Bilateral truncal vagotomy significantly delayed the gastric emptying time of the solid nutrient meal. However, after vagotomy, ICV infusion of CRF had no effect on gastric emptying time or the spatial and temporal parameters of gastro-pyloro-duodenal contractions. In conclusion, CRF, the mediator of stress response, delays the total gastric emptying time of solid nutrient meals. The delay in gastric emptying may not be due to a change in the spatial and temporal parameters of gastric or pyloric contractions, but mainly due to changes in the parameters of duodenal contractions. The central effects of CRF on gastric emptying and duodenal contractions may be mediated by the vagus nerves.     

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.     

Mechanisms underlying duodeno-gastric reflux in man

BACKGROUND: Recent studies suggest that duodeno-gastro-oesophageal reflux (DGER) contributes to the occurrence of reflux oesophagitis and Barrett's oesophagus. The mechanisms underlying duodeno-gastric reflux (DGR), a prerequisite for DGER, are poorly understood. AIMS: To study the occurrence of DGR in relation to interdigestive and postprandial gastroduodenal motility. SUBJECTS AND METHODS: Ten healthy subjects underwent stationary gastroduodenal manometry with simultaneous duodenal and antral Bilitec recording 4 h before and 5 h after ingestion of a liquid meal. Eight volunteers underwent the same study, with administration of erythromycin postprandially. RESULTS: During the interdigestive phase II, all volunteers had short DGR episodes. Postprandially, DGR occurred in all subjects, on average 39 +/- 28 min after the start of the meal, and was cleared from the stomach after 242 +/- 23 min. Induction of increased antral motility and of a premature phase III, by administration of erythromycin, was associated with faster gastric DGR clearance. However, there was no direct temporal relationship between erythromycin-induced gastric phase III and erythromycin-induced DGR clearance. CONCLUSION: In healthy subjects, duodenogastric reflux occurs sporadically in the interdigestive state and is a normal phenomenon in the postprandial period. Erythromycin induces faster clearance of DGR from the stomach, which depends on enhanced antral contractile activity rather than premature phase III.     

Gastric emptying of a non-digestible solid: assessment with simultaneous SmartPill pH and pressure capsule, antroduodenal manometry, gastric emptying scintigraphy

Abstract  Gastric emptying of digestible solids occurs after trituration of food particles. Non-digestible solids are thought to empty with phase III of the migrating motor complex (MMC). The aim of this study was to determine if a non-digestible capsule given with a meal empties from the stomach with return of the fasting phase III MMC or during the fed pattern with the solid meal. Fifteen normal subjects underwent antroduodenal manometry and ingestion of a radiolabelled meal and SmartPill wireless pH and pressure capsule. In five subjects, emptying of the SmartPill was studied in the fasting period by ingesting the SmartPill with radiolabelled water. The SmartPill emptied from the stomach within 6 h in 14 of 15 subjects. SmartPill pressure recordings showed high amplitude phasic contractions prior to emptying. SmartPill gastric residence time (261 ± 22 min) correlated strongly with time to the first phase III MMC (239 ± 23 min; r  = 0.813; P  < 0.01) and correlated moderately with solid-phase gastric emptying ( r  = 0.606 with T-50% and r  = 0.565 with T-90%). Nine of 14 subjects emptied the capsule with a phase III MMC. In five subjects, the SmartPill emptied with isolated distal antral contractions. In five subjects ingesting only water, SmartPill gastric residence time (92 ± 44 min) correlated with the time to the first phase III MMC (87 ± 30 min; r  = 0.979; P  < 0.01). The non-digestible SmartPill given with a meal primarily empties from the stomach with the return of phase III MMCs occurring after emptying the solid-phase meal. However, in some subjects, the SmartPill emptied with isolated antral contractions, an unappreciated mechanism for emptying of a non-digestible solid.     

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.     

37Autonomic nervous system response to a solid meal in healthy children: its relation to gastric myoelectrical activity

The current study examined whether electrogastrogram (EGG) patterns differ between children/adolescents and adults, including whether EGG recordings obtained from healthy children would be considered normal by standards established for adults. Twenty-eight healthy children (54% females; ages 8–17, M = 12.4 years) were evaluated and compared to 15 healthy adults. EGGs were recorded for 30 min in the fasting state and for 1 h following a standard meal. For both pediatric and adult participants, there was a significant increase in both the dominant frequency and the dominant power from the pre- to the post – prandial period (p < 0.001 for each). There was a significant post-prandial increase in the %normal slow waves in pediatric participants only (81.5 vs . 89.0% vs . p < 0.001). Children demonstrated a significantly lower mean fasting %normal slow waves (81.5% vs . 94.2%) and a significantly greater fasting % tachygastria (8.9% vs . 2.3%) than did adults. Other parameters did not differ. Using adult standards, the %normal slow waves were ≥70% of recording time in 96% children in the fasting state and in 100% in the postprandial period. A postprandial power increase was seen in 89% of the children. In conclusion, while adults should not be used as controls in pediatric studies of EGG, our data would indicate that American Motility Society (AMS) consensus adult criteria for a normal EGG are appropriate to apply to children and adolescents when utilizing methodology and meal challenge similar to that used to establish the adult norms.     

Effect of Intraduodenal Infusion of Acid on the Antropyloroduodenal Motor Unit in Human Volunteers

Intraduodenal acid has been shown to delay gastric emptying. We have investigated the effect of infusing hydrochloric acid into the duodenum on the motor activity of the gastric antrum, pylorus, and duodenum in 18 healthy volunteers. Pressures in the gastric antrum, pylorus, and duodenum and the pH in the antrum and duodenum were recorded in response to alternate duodenal infusions of normal saline and 0.1 M isotonic hydrochloric acid at constant (1 or 2 ml/min) or increasing (1, 2, 3.75, and 5 ml/min) rates. Repetitive infusions of acid (1 or 2 ml/min) were associated with 1) a decrease in antral pressure waves (p < 0.05), 2) a reduction in coordinated pressure waves involving the duodenum (p < 0.05) and replacement by random contractile activity, and 3) an increase in isolated pyloric pressure waves (IPPWs) (p < 0.05). Increasing the rate of acid infusion reduced the rate of coordinated contractions involving the antrum (r = -0.39; p < 0.01) and increased the rate of IPPWs (r = 0.45; p < 0.01). There were significant correlations between the percentage of time that the duodenal pH was less than 2, and both the rate of coordinated contractions involving the antrum (r = -0.28; p < 0.01) and the rate of IPPWs (r = 0.34; p < 0.01). These changes in antropyloroduodenal motor activity may contribute to the delay in emptying of acidic solutions from the stomach.     

Manometric responses of human duodenum during infusion of HCl,hyperosmolar saline,bile and oleic acid

Abstract Duodenal motor activity is incompletely understood. The purpose of this study was to define the contractile patterns of the duodenum that occur in response to rate controlled injection of various solutions. In nine healthy volunteers we placed a six channel perfused catheter, and recorded pressure activity in the antrum, pylorus and duodenum. Volumes of 10 and 20 mL of 0.9% NaCl, 100 mM HCl (pH 1), 5% NaCl (1711 mOsm/kg), human bile and iso-osmolar sodium oleate were randomly injected into the duodenum at 20 ml/min, starting IS min after phase III migratory motor complex (MMC). A 20 mL bolus of each solution caused more activity (P < 0.05) than a 10 mL bolus, but the motor pattern was similar. The control, 0.9% NaCl, produced occasional pressure waves, whereas bile and sodium oleate induced more (P < 0.05) activity which consisted of low amplitude, isolated or clusters (2–4 cycle/min) of non-propagating pressure waves that occurred at random sites. In three subjects, oleate produced isolated pyloric phasic contractions. In contrast, HCl and 5% NaCl induced high amplitude pressure waves that were seen either at a single channel or at multiple channels, occurring simultaneously. The motility index was also greater (P < 0.05) than that induced by other solutions. Additionally, within 2 min of infusion, a phase III MMC like pattern was observed in five of the nine subjects who received HCl and three of the nine who received 5% NaCl. A non-nutrient iso-osmolar solution induced occasional motor activity. HCl and hyperosmolar solutions induced more frequent and large amplitude, segmental contractions whereas lipid and bile induced fewer and smaller amplitude contractions. The volume, the pH, the osmolar and the nutrient make up of the infusate may each influence the duodenal motor responses.     

Role of Peptide YY in Intestinal and Gallbladder Motility in Dogs

The purpose of this study was to characterize the action of exogenous PYY, an ileocolonic peptide released by fatty meal, and that released by Heal perfusion with oleate on intestinal and gallbladder motility patterns and the posssible role of the adrenergic pathway in this action. Dogs were equipped with chronic duodenal electrodes for recording myoelectric activity and with a cannula in the gallbladder fundus for measuring the gallbladders intraluminal pressure and volume and calculating its motility index (MI) and emptying rate. After intravenous infusion of PYY, there was a dose-dependent prolongation of the migrating motor complex (MMC) interval and almost complete abolition of the contractions and emptying of gallbladder during the duodenal activity front. After meat feeding or during intravenous infusion of cerulein, 50 pmol/(kg · h), the MMC was interrupted and replaced by irregular spike activity, accompanied by a marked increase in the gallbladder MI and about 80% to 90% reduction of its volume. PYY, 200 pmol/(kg · h), reduced significantly the meal- or cerulein-induced duodenal spike activity but failed to affect the MI and volume of the gallbladder. Similar changes in fasted and fed patterns of motility were observed after Heal oleate (16 mM/h), producing plasma PYY levels in a range similar to that observed after infusion of exogenous PYY. The inhibitory effects of PYY or Heal fat on intestinal myoelectric activity were reversed in part by α-adrenergic blockade (phentolamine). We conclude that exogenous PYY or endogenous hormone released by Heal oleate inhibits the interdigestive and postprandial motility pattern of the small bowel but does not affect gallbladder motility, and that the inhibition of intestinal motility involves, at least in part, the adrenergic pathway.     

The migrating motor complex modulates intestinal motility response and rate of gastric emptying of caloric meals

Abstract The present study elucidates whether the phase of the migrating motor complex (MMC) present at the moment of food intake modulates postprandial motor response and rate of gastric emptying of caloric meals. Eight healthy male volunteers with a mean age of 26 years were examined twice. During water-perfused gastroduodenal manometry, a liquid meal with paracetamol added as a marker was orally administered during phase I and late phase II. Paracetamol appeared in serum 14.1 ± 3.8 min and 9.1 ± 4.0 (mean ± SD) min, respectively, after intake of the meal (P < 0.02). The area under the curve of s-paracetamol until 25 min after intake was 232 ± 169 μmoll_-1 min and 362 ± 130 (P < 0.05), respectively. When taken during late phase II, a phase III-like activity occurred within 2.1 ± 1.3 min in the duodenum, and was succeeded by quiescence. During phase I, the meal invariably initiated irregular contractions within 4 min. The phase of MMC during which a caloric meal is ingested modulates duodenal motor response and rate of gastric emptying during the initial postprandial period. Initial postprandial motor activity thus represents the combined effect of nutrient stimulation and the underlying enteric biorhythm as reflected by phase of MMC.