PURPOSE: This study was intended to investigate the migrating motor complex (MMC) changes after ileal bypass in ex-vivo mouse models. METHODS: Partial (side-to-side) and total bypass (occlusion of proximal part of bypassed loop) were performed on ileums of female Institute of Cancer Research mice. After 2 and 4 weeks, the bypassed segments were harvested and MMCs were recorded at 4 different sites ex-vivo. Amplitude, duration, interval, direction of propagation, and the area under the curve (AUC) of MMCs were measured and compared to those of the controls. RESULTS: In control mice (n = 7), most MMCs propagated aborally (91.1%). After 2 weeks of partial bypass (n = 4), there was a significant decrease in both amplitude and AUC, and orally-propagating MMCs increased significantly (45%, P = 0.002). Bidirectional MMCs (originating in the bypassed loop and propagating in both directions) were also observed (10%). The amplitude of the MMCs remained decreased at 4 weeks after partial bypass (n = 4), and neither the AUC nor the direction of propagation showed significant changes compared to 2 weeks. Similarly, in the total bypass model, both the amplitude and AUC of the MMCs decreased significantly compared to controls. In contrast to partial bypass, 95% of the MMCs within the bypassed loop propagated aborally after 2 weeks (n = 6), which was similar to the control state. After 4 weeks (n = 5), however, MMCs either lost their temporal relationship or completely disappeared. CONCLUSION: The changes in propagation direction of the MMCs in the partially bypassed loop may contribute to stagnation of bowel contents and the development of blind loop syndrome.
Animals ; Area Under Curve ; Blind Loop Syndrome ; Female ; Humans ; Ileum ; Jejunoileal Bypass ; Mice ; Myoelectric Complex, Migrating

Irritable bowel sydrome (IBS) is one of the most common disorders and a heterogeneous condition in view of symptoms and underlying mechanisms. Though underlying causes of pathophysiologic changes remain unclear, low grade mucosal inflammation and abnormal intestinal motility are accepted mechanisms which alter gut function and generate symptoms of IBS. First, before 1980s, abnormal colonic and rectal motor functions were regarded as the main pathophysiology of IBS, but only 25-75% of IBS patients have apparent motor abnormalities which differ from the motor functions in normal controls. So, various gastrointestinal motility tests were not indicated for the diagnosis of IBS. The high-amplitude propagating contractions of colon in IBS patients may be related to the visceral pain perception. Second, the low grade mucosal inflammation may be involved in the pathophysiology of visceral hypersensitivity. Post infectious IBS (PI-IBS) occupied 6-17% of the total IBS and some previous prospective studies reported that 7-33% of acute bacterial enteritis patients developed IBS after 6-12 months of infection. The relative risk of IBS in the gastroenteritis cohort was 11.9 and the strongest risk factor is the duration of diarrhea. After enteritis event, the increased number of immunocytes, mast cells and large amount of lymphocytes infiltration were revealed in mucosa and enteric nervous system of the gut. Beside the inflammatory cells, enterochromaffin cells, cytokines and inducible nitric oxide may be related to the pathophysiologic mechanism of PI-IBS. Lastly, the abnormalities in the gastrointestinal autonomic nervous system can induce constipation or motor disorders, but further research should elucidate it.
Gastrointestinal Motility ; Humans ; Inflammation ; Intestinal Mucosa/pathology ; Irritable Bowel Syndrome/pathology/*physiopathology ; Myoelectric Complex, Migrating

OBJECTIVETo explore the effect of electroacupuncture on myoelectric activity of Jejunal limb after Roux-en-Y esophagojejunostomy.

METHODSFourteen health young pigs were randomly divided into 2 groups, an experimental group (total gastrectomy and Roux-en-Y esophagojejunostomy was carried out) and a control group (the abdominal cavity was closed after the electrode was placed), 7 pigs in each group. Electroacupunture was given at "Zusanli" (ST 36) in the experimental group. The changes of myoelectrogram of the jejunal limb was investigated.

RESULTSCompared with the control group, the amplitude and the frequency of the slow wave, and the amplitude and incidence rate of the spike potential in the experimental group were changed significantly; the duration of migrating motor complex (MMC) phase III was (2.6 +/- 0.7) minutes in the experimental group, which was significantly shorter than (7.1 +/- 1.1) minutes in the control group. Electroacupuncture did not significantly influence the amplitude and the frequency of the slow wave, but could increased significantly the incidence rate and the amplitude of the spike potential; after electroacupuncture, the duration of MMC phase III was (5.7 +/- 0.9) minutes, which was significantly longer than (2.6 +/- 0.7) minutes before electroacupuncture.

CONCLUSIONElectroacupuncture at "Zusanli" (ST 36) can relieve the Roux-en-Y stasis syndrome through influencing myoelectric activity of the jejunum.

Anastomosis, Roux-en-Y ; Electroacupuncture ; Gastrectomy ; Humans ; Jejunum ; Myoelectric Complex, Migrating

OBJECTIVETo observe the changes and characteristics of interdigestive migrating motor complex (MMC) in rat models of acute liver failure.

METHODS30 rat models with acute liver failure were induced with D-galactosamine and another 30 normal rats were used as controls. The indexes of MMC recorded by multi-channel physiological recorder were compared.

RESULTSNo significant differences found between the two groups in antral and duodenal MMC cycles and frequencies of duodenal and jejunal MMC III phase. Compared with normal controls, the MMC II phase in the acute liver failure rats was significantly prolonged (t=-3.97, -3.85, P<0.05), the MMC III duration of antrum and duodenum (u=-4.99, t=4.66, P<0.05) was shorter and the MMC III frequency of antrum (u=-4.73, P<0.05) was faster. In addition, the MMC cycle and MMC III phase of jejunum were significantly prolonged (u=-1.63, t=-4.94, P<0.05) and the MMC III phase duration was significantly shorter in the acute liver failure rats (t=5.10, P<0.05).

CONCLUSIONSignificantly prolonged MMC II phase characterized by migrating clustered contraction, shortened MMC III phase and extended jejunal MMC cycles were probably the major contributors to the gastrointestinal motility disorders in the rats with acute liver failure.

Animals ; Liver Failure, Acute ; physiopathology ; Myoelectric Complex, Migrating ; Rats ; Rats, Wistar

Animals ; Dogs ; Duodenum ; physiology ; Male ; Myoelectric Complex, Migrating ; physiology ; Sphincter of Oddi ; physiology

OBJECTIVETo determine the effect of the area postrema (AP) of the medulla oblongata on gastrointestinal interdigestive migrating motor complex (MMC) and the plasma motilin level.

METHODSInterdigestive MMC activities of the antrum and duodenum were recorded by strain gauge implanted on the serosa of 8 conscious dogs. A cannula was intubated in femoral vein for motilin injection. The plasma motilin concentration was measured by RIA. We observed: (1) normal interdigestive MMC activity and fluctuations in plasma motilin concentration; (2) the effects of electrically damaging the AP on MMC activity and plasma motilin level; (3) whether intravenous injection of motilin could induce phase III contractions after the AP was destroyed.

RESULTS(1) Typical interdigestive MMC with phase I, II, III, and IV was recorded in normal dogs. Phase III was concurrent with the peak of plasma motilin level. (2) In damaged AP dogs, antroduodenal interdigestive MMC contractions were suppressed; cyclic, phasic and migratory pattern of MMC was disrupted. Plasma motilin concentration was decreased. Intravenous injection of motilin could not induce phase III contractions.

CONCLUSIONSThe area postrema might play an important role, which is mediated by motilin, on the regulation of interdigestive MMC.

Animals ; Dogs ; Fourth Ventricle ; physiology ; Medulla Oblongata ; physiology ; Motilin ; blood ; Myoelectric Complex, Migrating ; physiology ; Stomach ; physiology

Animals ; Colon ; physiology ; Female ; Indoles ; pharmacology ; Male ; Myoelectric Complex, Migrating ; Rats ; Rats, Wistar ; Viscera ; physiology

BACKGROUND/AIMS: High-resolution methods have advanced esophageal and anorectal manometry interpretation but are incompletely established for intestinal manometry. We characterized normal fasting duodeno-jejunal manometry parameters not measurable by standard techniques using clustered closely-spaced recordings. METHODS: Ten fasting recordings were performed in 8 healthy controls using catheters with 3–4 gastrointestinal manometry clusters with 1–2 cm channel spacing. Migrating motor complex phase III characteristics were quantified. Spatial-temporal contour plots measured propagation direction and velocity of individual contractions. Coupling was defined by pressure peak continuity within clusters. RESULTS: Twenty-three phase III complexes (11 antral, 12 intestinal origin) with 157 (95% CI, 104–211) minute periodicities, 6.99 (6.25–7.74) minute durations, 10.92 (10.68–11.16) cycle/minute frequencies, 73.6 (67.7–79.5) mmHg maximal amplitudes, and 4.20 (3.18–5.22) cm/minute propagation velocities were recorded. Coupling of individual contractions was 39.1% (32.1–46.1); 63.0% (54.4–71.6) of contractions were antegrade and 32.8% (24.1–41.5) were retrograde. Individual phase III contractions propagated > 35 fold faster (2.48 cm/sec; 95% CI, 2.25–2.71) than complexes themselves. Phase III complexes beyond the proximal jejunum were longer in duration (P = 0.025) and had poorer contractile coupling (P = 0.025) than proximal complexes. Coupling was greater with 1 cm channel spacing vs 2 cm (P < 0.001). CONCLUSIONS: Intestinal manometry using clustered closely-spaced pressure ports characterizes novel antegrade and retrograde propagation and coupling properties which degrade in more distal jejunal segments. Coupling is greater with more closely-spaced recordings. Applying similar methods to dysmotility syndromes will define the relevance of these methods.
Catheters ; Fasting ; Intestines ; Jejunum ; Manometry ; Muscle Contraction ; Myoelectric Complex, Migrating ; Periodicity

Little human tissue data are available for slow waves and migrating motor complexes, which are the main components of small bowel motility. We investigated the electrophysiological and mechanical characteristics of human ileal motility, in vitro. Ileum was obtained from patients undergoing bowel resection. Electrophysiological microelectrode recordings for membrane potential changes and mechanical tension recordings for contraction from smooth muscle strips and ileal segments were performed. Drugs affecting the enteric nervous system were applied to measure the changes in activity. Slow waves were detected with a frequency of 9~10/min. There were no cross-sectional differences in resting membrane potential (RMP), amplitude or frequency between outer and inner circular muscle (CM), suggesting that electrical activities could be effectively transmitted from outer to inner CM. The presence of the interstitial cell of Cajal (ICC) at the linia septa was verified by immunohistochemistry. Contractions of strips and segments occurred at a frequency of 3~4/min and 1~2/min, respectively. The frequency, amplitude and area under the curve were similar between CM and LM. In segments, contractions of CM were associated with LM, but propagation varied with antegrade and retrograde directions. Atropine, NW-oxide-L-arginine, and sodium nitroprusside exhibited different effects on RMP and contractions. There were no cross-sectional differences with regard to the characteristics of slow waves in CM. The frequency of contractions in smooth muscle strips and ileal segments was lower than slow waves. The directions of propagation were diverse, indicating both mixing and transport functions of the ileum.
Atropine ; Enteric Nervous System ; Humans* ; Ileum ; Immunohistochemistry ; Membrane Potentials ; Microelectrodes ; Muscle, Smooth ; Myoelectric Complex, Migrating ; Nitroprusside

OBJECTIVETo explore the impact of abnormal myoelectricity at gastroduodenal anastomosis on gastric emptying in rats.

METHODSRats were randomly divided into experimental group (n=16) and control group (n=16). Pylorectomy and end-to-end gastroduodenal anastomosis were performed in the experimental group and electrodes were implanted in the serosal surface adjacent to the anastomosis. Slow waves were recorded by the implanted electrode in vivo. Gastric emptying was examined by scintigraphy.

RESULTSAt the first week after surgery, antral slow-wave frequency was significantly lower in the experimental group (0.8±1.4 vs. 3.3±1.2, P<0.01), as was the duodenal slow-wave frequency (2.1±0.6 vs. 11.1±0.7, P<0.01). There was no consecutive slow-waves transduction across the pylorus or the anastomosis. Within 12-16 weeks after operation, antral slow-wave frequency in the experimental group and the control group were (8.7±0.6) cpm and (4.0±0.4) cpm, respectively (P<0.01), and duodenal slow-wave frequency were (11.1±0.8) cpm and (10.8±0.7) cpm, respectively (P>0.05). Retrograde and antegrade myoelectricity transduction through the anastomosis were detected. The mean semi-emptying time in the proximal stomach was 14.7 min in the experimental group and 13.6 min in the control group (P>0.05). Radionuclide retention rate was 25.4% in the experimental group and 39.4% in the control group (P>0.05). The mean semi-emptying time in the distal stomach was 25.3 min in the experimental group and 10.5 min in the control group (P<0.01). Radionuclide retention rate was 46.4% in the experimental group and 18.7% in the control group (P<0.01).

CONCLUSIONThe abnormal myoelectricity in the region of gastroduodenal stoma may delay liquid gastric emptying in pylorectomy rats.

Animals ; Duodenum ; physiology ; surgery ; Gastric Emptying ; physiology ; Gastroenterostomy ; Male ; Myoelectric Complex, Migrating ; physiology ; Rats ; Rats, Sprague-Dawley ; Surgical Stomas ; physiology