Duodenal Phase Research Articles

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.

Reproducibility of antroduodenal motility during prolonged ambulatory recording

Ambulatory recording of antroduodenal manometry is a novel technique with several advantages over standard stationary manometry recording. Although the feasibility of this technique in clinical practice has been demonstrated, reproducibility of antroduodenal motility recorded by means of ambulatory manometry has not been investigated. To test whether antroduodenal motility recorded by ambulatory manometry is reproducible, we performed two 24-h ambulatory antroduodenal manometry recordings in 18 healthy subjects according to an identical protocol with a 1-week interval. Motility was recorded with a five-channel solid-state catheter. Postprandial motility was recorded after consumption of two test meals and interdigestive motility was recorded nocturnally. Postprandial antroduodenal motor characteristics were identical between the separate recordings. The number and duration of nocturnal cycles of the interdigestive migrating motor complex were also in the same range. Phase III characteristics in general were not different between the two recordings. Only minor alterations were observed in the duration of phase III motor fronts with duodenal onset and in the number of interdigestive cycles concluded by duodenal onset phase III. Parameters obtained by qualitative analysis were comparable between the two recordings. The antroduodenal motility pattern, when measured by ambulatory recording with solid state catheters under standardized conditions, is very reproducible.

Human duodenal phase III MMC activity is not predominantly retroperistaltic

Human duodenal phase III MMC activity is not predominantly retroperistaltic

Human duodenal phase III MMC activity is not predominantly retroperistaltic

Human duodenal phase III MMC activity is not predominantly retroperistaltic

Pain associated with phase III of the duodenal migrating motor complex in patients with postcholecystectomy biliary dyskinesia

Background: Correlation between various gastrointestinal events and particular aspects of the migrating motor complex has been reported. This study correlates postcholecystectomy pain to variations in biliary pressure associated with the duodenal motor cycle. Methods: In 18 patients with postcholecystectomy pain and 10 control subjects, biliary and duodenal pressures were recorded simultaneously with microtransducers. After recording a spontaneous cycle, morphine was administered to induce a premature phase III and spasm of the sphincter of Oddi, and then cerulein was administered to stop the spasm. Results: Transient but significant elevations of biliary pressure occurred at duodenal phase III in both groups, but a greater percentage of the patients developed pain during phase III (89% vs. 20%, p < 0.01). Morphine produced premature phase III and biliary pressure elevation, which were accompanied by pain more frequently in the patients than in the control subjects (78% vs. 30%, p < 0.05). Biliary pressure dropped after the cerulein injection, relieving the pain in 13 of 14 patients and in 2 of 3 control subjects who had morphine-induced pain. The phase III–related pain was relieved by endoscopic sphincterotomy in 14 of 15 patients. Conclusions: The cyclic elevation of biliary pressure in coordination with phase III of the duodenal motor cycle may contribute to the development of pain in patients with postcholecystectomy biliary dyskinesia. (Gastrointest Endosc 2000;51:528-34.)

Sphincter of Oddi motility in patients with hepatolithiasis and common bile duct stones.

The purpose of this study was to explore a difference in sphincter of Oddi (SO) motor activity among patients with intrahepatic (I, N = 5), intra- and extrahepatic (IE, N = 15), and common bile duct (CBD, N = 6) stones. Interdigestive motility of the SO and duodenum was studied by pneumohydraulic infusion manometry via the percutaneous route. SO phasic contractions showed a cyclic change in concert with the duodenal migrating motor complex (MMC) in all these patients. There was no significant difference in the cycle length, frequency, or amplitude of the SO phasic waves among the three groups throughout the whole cycle. The SO basal pressure during duodenal phases I and II of the duodenal MMC was significantly lower in patients with the IE type of hepatolithiasis than in those with the I type (P = 0.04), but there was no significant difference during phase III between the two groups. The SO basal pressure during phases I and II of the CBD group was also significantly lower than that of the I group (P = 0.02). The significance became even more prominent (P = 0.001) when a subgroup of patients with a dilated CBD (diameter > 1 cm) was examined. Lower basal pressure in the IE group or CBD group than in the I group suggested that stones in the common duct might injure or irritate the SO and cause SO dysfunction. In the subgroup with dilated CBD, which may have resulted from repeated and severe SO injury, the statistics became more prominent.

A normal gastrointestinal motility excludes chronic intestinal pseudoobstruction in children.

Gastrointestinal manometry has gained wide acceptance in the approach to patients with suspected enteric neuromuscular disorders. However, performing gastrointestinal manometry in these subjects without a previous exhaustive diagnostic evaluation is unjustified. Twelve children (median age: 7.0 years; range: 8 months-13 years), with clinical and x-ray features suggesting chronic intestinal pseudoobstruction, were referred to our unit for gastrointestinal manometry. The latter was performed with a perfused catheter for 5 hr in the fasting state and for 90 min after feeding. Data were compared with those recorded in eight age-matched controls. In all patients and controls, interdigestive motor complexes with propagated phases III were detected; a regular postprandial antroduodenal motor activity was also recorded. Patients and controls did not differ for fed antral and duodenal motility indexes, fed antroduodenal coordination, and length of duodenal phase III. Most of the patients showed short or prolonged bursts of nonpropagated activity in the fasting and/or fed states; in four cases fasting and/or fed sustained phasic activity was recorded. Manometric evidence of migrating motor complexes and postfeeding activity did not support the diagnosis of intestinal pseudoobstruction and suggested redirecting the diagnostic evaluation. Final diagnoses were: Munchausen syndrome-by-proxy (four cases), celiac disease (two cases), intestinal malrotation (two cases), Crohn's disease (two cases), multiple food intolerance (one case), and congenital chloride-losing diarrhea (one case). It is concluded that in children with suspected chronic intestinal pseudoobstruction manometric evidence of migrating motor complexes and fed motor activity excludes an enteric neuromuscular disorder and suggests a reassessment of the diagnostic work-up. Furthermore, if gastrointestinal manometry shows migrating motor complexes and postfeeding motor activity, qualitative abnormalities of the manometric tracings do not indicate an underlying enteric neuromuscular disorder and must not be overemphasized. Patients referred for gastrointestinal manometry should previously undergo an extensive diagnostic investigation to exclude disorders mimicking chronic intestinal pseudoobstruction.

Scintigraphic Assessment of Interdigestive Duodenogastric Reflux in Humans: Distinguishing between Duodenal and Biliary Reflux Material

Background: Late duodenal phase III is characterized by retroperistalsis. The physiologic function of this phenomenon is unknown. Our aim was to study the relationship between duodenal motility and the transport of duodenal contents from the biliary tract and the duodenum by using a double-isotope technique. Methods: Manometric analysis of the direction of interdigestive duodenal pressure waves was performed in 12 volunteers. Duodenal marker was infused directly into the proximal duodenum, and bile marker was infused intravenously for 2 h. Radionuclide activity was examined for regions corresponding to the stomach, gallbladder, and duodenum. Results: In phase II, antegrade pressure waves dominated with propulsion of both markers to the jejunum. Retroperistalsis occurred in 90% of the activity fronts and was always (100%) followed by retropulsion of duodenal marker to the stomach. A clear-cut reflux of bile marker was seen in only 17% of the activity fronts. The incidence rate of duodenogastric reflux was highest in phase III (P = 0.008) compared with phase II with an infrequent (P = 0.002) admixture of bile. Bile marker contents increased abruptly in the gallbladder during phase III. Conclusions: Late phase III acts as a retroperistaltic pump, retropelling duodenal contents to the stomach. In this physiologic duodenogastric reflux, bile is avoided by deviation to the gallbladder, probably by a phase III-associated occlusion of the sphincter Oddi.

In Dyspeptic Patients without Gastric Phase III of the Migrating Motor Complex, Helicobacter pylori Eradication Produces no Short-term Changes in Interdigestive Motility Pattern

Background: The relationship between Helicobacter pylori infection and interdigestive gastroduodenal motility in functional dyspepsia is still uncertain. Recent data from a large series documented that in dyspeptic patients without gastric phase III of the interdigestive migrating motor complex (MMC), the prevalence of bacterial infection was significantly higher. Since most H. pylori-positive dyspeptic patients have coexisting chronic gastritis, whether or not dyspepsia per se rather than bacterial colonization or chronic inflammation of the gastric mucosa may account for the observed interdigestive motility pattern is unknown. Our aim was to compare the interdigestive gastroduodenal motility pattern and dyspeptic symptoms before and 1 month after bacterial eradication in 20 H. pylori-positive dyspeptic subjects with chronic non-atrophic gastritis and without gastric phase III of the MMC, who were randomly allocated to receive eradication treatment (n = 10) or not (n = 10). Methods: Upper GI endoscopy with duplicate biopsies in antrum and corpus, 240-min interdigestive gastroduodenal manometric recording and symptoms assessment were performed before and 1 month after the treatments; bacterial eradication was confirmed by 13C-urea breath test. Results: After H. pylori eradication, neither in the incidence of antral and duodenal phase III of MMC nor in the phase II motility index values were any changes observed. Symptomatic improvement was recorded in both groups, with no significant differences between eradicated patients and controls. Conclusions: In dyspeptic patients with chronic non-atrophic gastritis and without gastric phase III of MMC, H. pylori eradication influences neither the interdigestive motility pattern nor the symptoms in the short-term period.

Motility of the Roux-en-Y hepaticojejunostomy in asymptomatic patients

OBJECTIVE: The aim of our study was to describe the motility in the limb, the duodenum, and the jejunum distal to the limb after Roux-en-Y hepaticojejunostomy in patients who remained asymptomatic postoperatively. Our objective was to obtain reference manometric recordings for interpretion of recordings in symptomatic patients. METHODS: Manometric recordings were obtained in the Roux-en-Y limb in 13 patients 15.6 ± 1.1 days postoperatively, using a probe inserted into the limb during surgery and coming out through the abdominal wall. The recording openings were positioned in the limb itself in eight patients, and also in the jejunum immediately distal to the limb in five patients. In four of eight patients, limb manometry was combined with duodenal manometry using a second probe introduced nasally. RESULTS: Phase IIIs were recorded in all 13 patients, either spontaneously or after trimebutine stimulation (100 mg i.v.). Phase IIIs occurred spontaneously in 12 patients. They always migrated throughout the Roux-en-Y limb, and were also most often observed in the distal jejunum; migration stopped in the distal jejunum in three of five patients. Phase IIIs in the limb occurred independently from duodenal phase IIIs. In the limbs, the duration of phase IIIs was longer ( p < 0.02), and the migration slower than in the duodenum ( p < 0.001) and in controls ( p < 0.02). In nine of 13 patients, injection of trimebutine (100 mg i.v.) initiated phase III in the Roux limb or in the distal jejunum within 2 min. During the combined recordings, trimebutine initiated phase III simultaneously in the duodenum and in the limb. The response to meals in the limb was poorer than in controls. Interruption of phase IIIs was shorter, and the area under the postprandial curve was smaller ( p < 0.01) for each postprandial half-h. Postprandial motility was poorer in the limb than in the distal small bowel ( p < 0.01). CONCLUSIONS: In asymptomatic patients, interdigestive motility is present in the hepaticojejunostomy Roux-en-Y limb, but it is abnormal because of slow migration of phase IIIs. The second abnormality observed in the limb is a response to meals that is both short and of low amplitude.

Motility of The Roux-En-Y Hepaticojejunostomy in Asymptomatic Patients

The aim of our study was to describe the motility in the limb, the duodenum, and the jejunum distal to the limb after Roux-en-Y hepaticojejunostomy in patients who remained asymptomatic postoperatively. Our objective was to obtain reference manometric recordings for interpretion of recordings in symptomatic patients. Manometric recordings were obtained in the Roux-en-Y limb in 13 patients 15.6 +/- 1.1 days postoperatively, using a probe inserted into the limb during surgery and coming out through the abdominal wall. The recording openings were positioned in the limb itself in eight patients, and also in the jejunum immediately distal to the limb in five patients. In four of eight patients, limb manometry was combined with duodenal manometry using a second probe introduced nasally. Phase IIIs were recorded in all 13 patients, either spontaneously or after trimebutine stimulation (100 mg i.v.). Phase IIIs occurred spontaneously in 12 patients. They always migrated throughout the Roux-en-Y limb, and were also most often observed in the distal jejunum; migration stopped in the distal jejunum in three of five patients. Phase IIIs in the limb occurred independently from duodenal phase IIIs. In the limbs, the duration of phase IIIs was longer (p < 0.02), and the migration slower than in the duodenum (p < 0.001) and in controls (p < 0.02). In nine of 13 patients, injection of trimebutine (100 mg i.v.) initiated phase III in the Roux limb or in the distal jejunum within 2 min. During the combined recordings, trimebutine initiated phase III simultaneously in the duodenum and in the limb. The response to meals in the limb was poorer than in controls. Interruption of phase IIIs was shorter, and the area under the postprandial curve was smaller (p < 0.01) for each postprandial half-h. Postprandial motility was poorer in the limb than in the distal small bowel (p < 0.01). In asymptomatic patients, interdigestive motility is present in the hepaticojejunostomy Roux-en-Y limb, but it is abnormal because of slow migration of phase IIIs. The second abnormality observed in the limb is a response to meals that is both short and of low amplitude.

The variability of the incremental postprandial portal vein flow response is partly caused by a relationship between fasting flow rate and phase activity of the migrating motor complex.

Results from studies on portal flow rate (PFR) have demonstrated a considerable intra- as well as interindividual variability of the incremental integrated response (IIR). We hypothesized that part of the variation of the IIR might be related to variability of the fasting PFR caused by a relationship between PFR and characteristics of the migrating motor complex (MMC). We examined 12 healthy men and PFR was recorded by using the percutaneous colour Doppler technique. Gastric emptying (GE) was determined by scintigraphy and the meal consisted of an omelette of 100 g (1400 kJ; 60% fat, 20% protein, 20% carbohydrates) tagged with 99mTc sulphur colloids followed by 150 ml water mixed with 111In DTPA. The design included recording of PFR in phase II as well as in phase III of the MMC. Meal ingestion took place in the following duodenal phase I. Postprandial recordings of GE and PFR were performed at 10 min intervals for the following 2 h. Median (95% confidence limits) amount of solid emptied at 120 min was 68% (59-81%). PFR in phase III was significantly higher than in phase II (1.56 l/min (1.35-1.93 l/min) vs 0.96 l/min (0.84-1.12 l/min), P< 0.001). PFR increased after the meal and a peak flow of 2.19 l/min (1.58-2.46 I/min) was recorded 10 min after ingestion (P< 0.01 vs phase III). Based on these characteristics a difference in IIR is to be expected, and the calculations revealed that IIR is considerably higher in the phase II series than in the phase III series (50 l/min x 120 min (8-90 l/min) vs -26 l/min x 120 min (-55 to 1 l/min), P< 0.001). In both series a weak but significant inverse relationship was demonstrated between amounts emptied during a 20-min period and the corresponding IIR (n = 72; r = -0.27, P< 0.05 (III); r = -0.29; P< 0.05 (II)). We conclude that fasting PFR is related to phase activity of the MMC and characteristics of the postprandial IIR depend upon MMC activity at the time of recording of the fasting value. Future studies on PFR need to be performed with phase related recording of fasting flow and meal ingestion in relation to preselected characteristics of the MMC.

Effect of intravenous amino acids on interdigestive antroduodenal motility and small bowel transit time

BackgroundPatients on total parenteral nutrition have an increased risk of developing gallstones because of gall bladder hypomotility. High dose amino acids may prevent biliary stasis by stimulating gall bladder emptying.AimsTo...

Impact of corticotropin-releasing hormone on gastrointestinal motility and adrenocorticotropic hormone in normal controls and patients with irritable bowel syndrome

Background—Corticotropin-releasing hormone (CRH) plays a key role in modulating intestinal motility in stressed animals.Aims—To evaluate the effect of CRH on intestinal motility in humans and to determine whether patients with...

Central inhibition of nitric oxide synthase modulates upper gastrointestinal motor activity.

We investigated the role of central nitric oxide (NO) synthase inhibition in the modulation of fasting gastrointestinal motor activity and gastric emptying rate of solid nutrient meals in conscious dogs. N(omega)-nitro-L-arginine methyl ester and N(omega)-nitro-L-arginine were infused intracerebroventricularly. Circular muscle contractions were recorded with surgically implanted strain gauge transducers. Gastric emptying was measured by a radiolabeled meal. The inhibition of NO synthase in the brain suppressed phase III activity in the stomach and the duodenum but not in the jejunum or the ileum. However, the central inhibition of NO synthase had no significant effect on the rate of gastric emptying of solid nutrient meals or the duration of postprandial disruption of migrating motor complex cycling. The central actions of NO synthase inhibition were blocked by bilateral truncal vagotomy but not by intravenous administration of propranolol or phentolamine. We conclude that the inhibition of NO synthase in the brain generates a stimulus that selectively inhibits gastric and duodenal phase III activities. This stimulus, however, may not affect the postprandial gastroduodenal motor activity or the rate of gastric emptying of solid nutrient meals.

A Double-Blind Placebo-Controlled Study on the Effects of Omeprazole on Gut Hormone Secretion and Gastric Emptying Rate

Background: The present study was designed to investigate whether an effect of omeprazole on gastric emptying is related to changes in the secretion of selected gut hormones. Methods: The studies were performed in healthy men after 10 days' treatment with 40 mg omeprazole daily/placebo. Food ingestion took place in a duodenal phase I, and the meal consisted of an omelette labelled with technetium Tc 99m, followed by 150 ml water labelled with indium In 111. Plasma concentrations of gastrin, cholecystokinin (CCK), and motilin were measured. Results: Pretreatment with omeprazole reduced gastric emptying rates. This applied to all variables and was most pronunced with regard to amounts of solid (median (95% confidence interval)) emptied at 180 min (71% (48-86) for omeprazole versus 96% (87-100) for placebo; P < 0.01). All median values of plasma gastrin concentrations from the omeprazole series were higher than the corresponding values from the placebo series, and omeprazole induced a tenfold increase in incremental integrated area (IIA, pmol/1 × 180 min) of the gastrin concentration curve (5250 (2570-9680) versus 575 (240-1485); P < 0.01). New findings include a lower postprandial secretion of CCK in the omeprazole series and, consequently, a difference in total integrated area (TIA, pmol/1 × 180 min) (88 (21-147) versus 217 (104-267); P < 0.05) and IIA (pmol/1 × 180 min) (52 (2-142) versus 165 (104-195); P < 0.05), respectively; a difference in IIA-30 (pmol/1 × 30 min) of plasma motilin concentrations (270 (140-595) (omeprazole) versus 460 (285-655); P < 0.05); and a direct relationship between the amounts of liquid emptied at 30 min and the corresponding TIA-30 of plasma motilin in the omeprazole (Rs = 0.667; P <0.05) and the placebo series (Rs = 0.767; P <0.05). Conclusion: Pretreatment with 40 mg omeprazole daily decreases the gastric emptying rates and has a substantial influence on the secretion of gastrin, motilin, and CCK. The finding of an omeprazole-induced decrease in CCK release may have clinical implications. Further investigation into the possible effect of proton-pump inhibitors on biliary tract motility and cholesterol solubilization in gallbladder bile is warranted.

Nocturnal antral pH rises are related to duodenal phase III retroperistalsis.

The mechanisms behind nocturnal rises of gastric pH are unknown. We have analyzed the relation between interdigestive duodenal peristalsis and nocturnal pH in the gastric antrum. Simultaneous recording of antroduodenal pressures and intragastric pH was performed in 11 healthy subjects (six men, five women) overnight for 8 hr, using a catheter with seven pressure recording points and an antral glass pH electrode. Three pressure recording sites were closely spaced in the descending duodenum. Altogether 46 phase III activities were recorded. A retroperistaltic sequence in the last part of phase III was observed in 31 phase III activities (67.4%), while 15 phase III activities lacked retroperistalsis. All subjects had retroperistalsis in at least one phase III at night with a median of 60% (52-100%) (interquartile range). The duration of the whole phase III was 5.1 (3.1-7.0) min, whereas the duration of the retroperistaltic period was 2.0 (1.5-3.2) min, corresponding to 45% (23-64%) of the duration of phase III. The peak of antral pH occurred 7.4 (6.0-13.0) min from the start of the phase III in the duodenum and and the rise in pH lasted for 8.0 (4.8-12.0) min. Measurement of pH for a period of 10 min before and after phase III, demonstrated an increase in median pH from 1.2 (1.1-1.9) to 3.2 (1.6-4.7), respectively (P < 0.001). Phase III activities without duodenal retroperistalsis were not followed by a significant antral pH change (median 1.7 vs 1.8 before and after phase III, respectively). Increases of pH unrelated to phase III were uncommon, only 1.0 (1.0-2.2) events per night were observed and lasted for a short period of time, 2.1 (0.5-3.2) min. The results indicate that the cyclic rise in antral pH at night is due to a physiological duodenogastric reflux, caused by duodenal retroperistalsis in phase III. This reflux may play a role in protection of the antral mucosa.

Duodenal Juxtapyloric Retroperistalsis in the Interdigestive State in Humans

Background: The last part of phase III of the migrating motor complex (MMC) is characterized by retroperistalsis in the descending duodenum. This study focused on MMC-related juxtapyloric peristalsis. Methods: Antroduodenal manometry was performed in 10 healthy subjects. Pressure was recorded in the distal antrum and in four consecutive subsegments (DS1-DS4), 15 mm each, in the juxtapyloric duodenum. Results: In the period with ongoing antral phase-Ill activity (early duodenal phase III) the antral pressure waves were antegrade, but in the juxtapyloric duodenum (DS1) retrograde waves predominated (median, 66%; interquartile range (IQR), 33–83%); that is, most duodenal pressure waves were directed against the antral ones. More distally, in DS3 and DS4, only 17% and 25% (IQR, 0–17, 0–33%, respectively) of the pressure waves were retrograde in this period. After the end of antral phase III– that is, in late duodenal phase III–the proportion of retrograde pressure waves increased successively to 91.5% (IQR, 66–100%) in DS2, 74.5% (IQR, 50–100%) in DS3, and 66% (IQR, 8.2–95.8%) in DS4, respectively, before the onset of duodenal motor quiescence. In phase II antegrade pressure waves predominated (63–76%, medians) in all four duodenal subsegments examined. Conclusions: During the interdigestive phase III the antral perstalsis is antegrade, but most juxtapyloric duodenal pressure waves are retrograde; that is, antral and duodenal contractions are on a collision course. In the proximal part of the descending duodenum the end of duodenal phase III shows retroperistalsis after the onset of phase I in the gastric antrum. These motor patterns may be important for regulation of the chemical milieu in the juxtapyloric area.

Exogenous motilin stimulates endogenous release of motilin through cholinergic muscarinic pathways in the dog

BACKGROUND & AIMS: Exogenous motilin is believed to stimulate endogenous release of motilin, but this has not been studied in detail. The aim of this study was to investigate whether and by what mechanism exogenous motilin stimulates endogenous release of motilin in the dog. METHODS: Gastric and duodenal contractile activity in conscious dogs was monitored by chronically implanted force transducers. Plasma canine motilin (c-motilin) concentrations in response to exogenous porcine motilin (p-motilin) were determined by specific radioimmunoassay for c- motilin. The release of motilin from motilin cells obtained from canine duodenal mucosa was studied in vitro using a perifusion system. RESULTS: In vitro, c-motilin release was stimulated by carbachol but not by p-motilin, and the carbachol-induced c-motilin release was inhibited by atropine. In vivo, exogenous p-motilin stimulated endogenous c-motilin release and gastric and duodenal phase III-like contractions; this motilin-induced motilin release was inhibited by atropine, hexamethonium, and a 5-hydroxy-tryptamine 3 receptor antagonist. CONCLUSIONS: In the dog, exogenous motilin stimulates endogenous motilin release through muscarinic receptors on motilin- producing cells via preganglionic pathways involving 5- hydroxytryptamine 3 receptors. (Gastroenterology 1996 Dec;111(6):1456-64)

Effects of 5-hydroxytryptamine agonists on myoelectric activity of the forestomach and antroduodenal area in sheep.

To increase knowledge of the role of 5-hydroxytryptamine (5-HT) receptors in the regulation of reticuloruminal, omasal and antroduodenal myoelectric activity in sheep, the effects of 5-HT agonists on forestomach and antroduodenal myoelectric activity have been investigated in conscious sheep. 5-Carboxamidotryptamine, methysergide, alpha-methyl-5-HT, 2-methyl-5-HT, cisapride, zacopride or metoclopramide were infused intravenously for 5 min and myoelectric recordings were obtained from electrodes chronically implanted in the reticulum, rumen (dorsal sac), omasal body, abomasal antrum and duodenal bulb. The integrated activity of the reticular and ruminal spike bursts was modified only by the highest doses of alpha-methyl-5-HT, 2-methyl-5-HT, metoclopramide and cisapride. A phase III-like activity pattern was recorded in the antroduodenal area with all 5-HT-ergic agents and a dose-dependent inhibition of myoelectric activity was recorded in both reticulorumen and omasum at the same time as the antroduodenal effects. In the forestomach, methysergide alone induced inhibition of ruminal secondary contractions; 5-HT, alpha-methyl-5-HT, cisapride and metoclopramide, moreover, evoked an initial dose-dependent increase in antral activity. These results suggest that 5-HT1, 5-HT2, 5-HT3 and 5-HT4 receptors are involved in the regulation of the migrating myoelectric complex in sheep and in the genesis of forestomach hypomotility that is occasionally recorded concomitantly with the spontaneous duodenal phase III in sheep. 5-HT4 receptors also have a prokinetic action in the antral area.