SEARCH · PubMed Health

Results for “Myoelectric Complex, Migrating”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 631 records · Page 35Linked to original sources

PubMed2006

Effects of feeding a standard diet on duodenal impedancometry in pigs.

The effects of gastric feeding on intestinal motility are still under debate. In order to better define the character of the contractile activity in fed and fasting states, we used the impedance technique to investigate the duodenal time periods of the migrating motor complex (MMC) and the interdigestive phases I-III. During general anaesthesia, pigs (32-40 kg) were instrumented with a luminal impedance catheter into the proximal duodenum in fasting (n = 6) and fed states (n = 6, Muskator, 400 g, Muskator-Werk, Düsseldorf, Germany). Duodenal motility was recorded continuously for 4 h, which made it possible to determine the length of interdigestive phases I-III and the MMC cycle. Differences between the groups were compared by using the Wilcoxon Rank-Sum Test. Feeding patterns were only found in pigs in the fed state. The subsequent MMC cycle length was shortened by 34% (p = 0.007) which was due to a shortened phase I of the MMC cycle (p = 0.014). While phase II seemed to be unaffected, phase III was prolonged by 31% after feeding had occurred (p = 0.012). The present study suggests that a standard maintenance diet disrupts the spontaneous MMC cycles by turning into fed pattern with the subsequent MMC cycle length being shortened. This was mainly due to a shortened phase I.

Animal Feed↗

PubMed2002

Role of the area postrema of medulla oblongata in the regulation of canine interdigestive migrating motor complex.

OBJECTIVE: To determine the effect of the area postrema (AP) of the medulla oblongata on gastrointestinal interdigestive migrating motor complex (MMC) and the plasma motilin level. METHODS: Interdigestive 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. CONCLUSIONS: The area postrema might play an important role, which is mediated by motilin, on the regulation of interdigestive MMC.

Animals↗

PubMedDate not supplied

Effect of omeprazole on interdigestive gastroduodenal motility of patients with ulcer-like dyspepsia.

BACKGROUND/AIMS: As omeprazole, an antisecretory drug, is largely used in the treatment of acid-related diseases, we investigated its effects on the interdigestive gastroduodenal motility of ulcer-like dyspepsia. METHODOLOGY: Gastroduodenal motility was recorded manometrically in 9 patients complaining of ulcer-like dyspepsia with normal gastric emptying at scintigraphy, without ulcerative lesions and H. pylori infection at endoscopy, and without diseases known to affect gut motility (group ULD), and in a group of 9 healthy subjects as control (group C). After a period sufficient to record two consecutive phases III of the migrating motor complex (MMC) in patients of group ULD, omeprazole 20 mg was infused intravenously 30 min after the end of the last duodenal phase III and the recording was continued to the next one. RESULTS: With respect to the control group, the group ULD showed a significantly longer MMC cycle duration, a frequent absence of gastric phases III and a shorter duration of duodenal phases III. Omeprazole administration in group ULD was followed after 18.9 +/- 8.5 min by a typical gastroduodenal phase III and, consequently, the duration of the omeprazole-related cycle was significantly shortened. These omeprazole-related phases III started from the stomach in nearly all cases and showed a significantly longer duration at the duodenal level with respect to the spontaneous ones. CONCLUSIONS: Patients with ulcer-like dyspepsia showed a decrease in frequency and duration of gastroduodenal phases III. The omeprazole intravenous administration induced the anticipated appearance of an apparently normal gastroduodenal phase III, probably by suppressing the inhibitory action of acid secretion.

Adult↗

PubMed1995

Effect of octreotide on fasting gall bladder emptying, antroduodenal motility, and motilin release in acromegaly.

Subcutaneous octreotide (Sandostatin) injections lead to gall stone formation in 13-50% of acromegaly patients during one year of therapy. This study explored the effects of octreotide on interdigestive gall bladder emptying, antroduodenal motility, and motilin release. Ambulatory antroduodenal manometry was performed in six acromegaly patients before and after two months of octreotide therapy (100 micrograms thrice daily, subcutaneously). Ultrasonographic gall bladder volume measurements and plasma motilin concentrations were obtained during two migrating motor complex (MMC) cycles. Before octreotide treatment, nine of 26 phase III activities started in the antrum and 17 of 26 in the duodenum whereas during treatment 47 of 48 of phase III activity started in the duodenum (p < 0.05). Before treatment, interdigestive gall bladder emptying (mean (SEM) 39.9 (4.0)% of maximal fasting volume) and plasma motilin peaks preceded antral phase III but not duodenal phase III. During octreotide therapy no significant motilin fluctuation or gall bladder emptying was seen. Fasting gall bladder volume increased from 40.9 (9.1) ml before to 68.0 (14.8) ml (p < 0.05) during octreotide treatment. In conclusion, two months' treatment with octreotide increases the number of duodenal phase III like activity and virtually abolishes antral phase III, plasma motilin peaks, and interdigestive gall bladder emptying. These effects might contribute to the high risk of gall stone formation during longterm octreotide treatment.

Acromegaly↗

PubMedDate not supplied

Gastrointestinal motility of patients with Roux-en-Y reconstruction.

The electromyographic activity of the gastrointestinal tract was studied in 28 patients undergoing gastric, biliary, and pancreatic operations with reconstruction of the gastrointestinal tract with a Roux-en-Y limb. The Roux-en-Y limb was constructed 1 to 5 years before the study in 8 patients (chronic Roux-en-Y) and at the operation in which the electrodes were implanted in 20 patients (recent Roux-en-Y). All four phases of the migrating motor complex (MMC) were identified in the gastrointestinal tract, including in the Roux-en-Y limb. The duration of the MMC was 82.4 +/- 22.3 min in the patients with chronic Roux-en-Y and 89.0 +/- 25.1 min in the patients with recent Roux-en-Y. Food ingestion converted the MMC to the fed pattern in the entire gastrointestinal tract, including the Roux-en-Y limb in 16 (76.2%) of 21 recordings of the patients with chronic Roux-en-Y and in 27 (84.4%) of 32 recordings of the patients with recent Roux-en-Y. The duration of the fed pattern was 170 +/- 34 min in the patients with chronic Roux-en-Y and 154 +/- 26 min in the patients with recent Roux-en-Y. The findings of this study indicate that the electromyographic activity of the Roux-en-Y limb is normal during both fasting and fed states, even many years after the construction of the Roux-en-Y.

Anastomosis, Roux-en-Y↗

PubMed2000

Obstructive jaundice, bacterial translocation and interdigestive small-bowel motility in rats.

BACKGROUND/AIMS: Translocation of gut bacteria occurs in obstructive jaundice, the underlying mechanisms are unclear. We designed this experimental study to investigate the association between interdigestive motility and the pathogenesis of bacterial translocation during biliary obstruction. METHODS: Rats were fitted with jejunal myoelectrodes for the measurement of the interdigestive migrating motor complex (MMC) and with two cannulas in the proximal common bile duct (CBD) for exteriorization of biliary flow. This allowed measurement of MMCs under control conditions with an intact enterohepatic circulation and during 3 days of CBD obstruction without surgical intervention. Mesenteric lymph nodes, liver, spleen and segments of the duodenum, the jejunum and the caecum were removed for microbial culturing. RESULTS: The MMC cycle length increased from 17.3 min before CBD obstruction to 31.9, 34.1, and 25.3 min on days 1, 2 and 3, respectively, after CBD obstruction (p < 0.05 for all days). Bacterial levels in the jejunum were significantly higher in CBD-obstructed rats than in control rats. The translocation incidence was significantly higher in rats with CBD obstruction (6/8) than in control rats (1/8). The bacterial levels in the jejunum correlated significantly with the MMC cycle length (r = 0.60, p <0.05). CONCLUSION: Experimental biliary obstruction is associated with disturbance of MMCs, small-bowel bacterial overgrowth and increased bacterial translocation.

Animals↗

PubMed1996

Increase of swallows before onset of phase III of migrating motor complex in normal human subjects.

The aim of our study was to analyze the relation between the deglutitive activity and fasting esophageal and gastric motility in normal subjects. Fifteen healthy subjects (9 males, 6 females) with a mean age of 42 years (range 19-65) were studied. A 24-hr pH-manometric recording was performed using a probe with four solid-state recording sites 10 cm apart, placed so as to record the motor activity of esophageal body, lower esophageal sphincter (LES) or distal part of the esophagus, and gastric antrum. An additional probe with one recording site was placed in the pharynx to evaluate swallowing. A pH electrode was also placed at 5 cm above the sphincter. Data were transferred to a personal computer and analyzed using specific software. Subjects received two meals during the recording session. MMCs were almost exclusively recorded during the nighttime. A mean of 2 +/- 0.94 (SD) MMC per subject was detected with a mean (+/- SD) interval, between each cycle, of 86.11 +/- 34.53 min. During the 30 min preceding gastric phase III, the number of swallows showed an increase that reached statistical significance 5 min before the onset of phase III. A similar pattern was observed for the area under the curve (AUC) of the esophagus and LES. In conclusion deglutition and esophageal motility vary with the MMC, suggesting that the deglutitive activity is part of the interdigestive motility pattern.

Adult↗

PubMed2004

Relationship between intraduodenal 5-hydroxytryptamine release and interdigestive contractions in dogs.

BACKGROUND: 5-hydroxytryptamine (5-HT) is released into the intestinal lumen during the fasting state. However, the relationship between the intraduodenal 5-HT and the interdigestive cyclic motor activity in conscious dogs is unclear. AIM: To correlate intraduodenal 5-HT concentrations with the interdigestive gastroduodenal migrating motor complex (MMC). METHODS: 6 dogs were implanted with 2 force transducers for recording gastroduodenal contractions and 2 catheters for measuring duodenal volume by a non-absorbable marker perfusion technique. Intraduodenal 5-HT concentrations were determined by high performance liquid chromatography at 5-min intervals. RESULTS: During fasting, gastroduodenal motor activity cycled as the MMC; luminal 5-HT concentrations and total outputs varied cyclically in temporal association with the MMC. Mean 5-HT concentrations peaked during phase II (P<0.05 vs. phase I and III), and 5-HT outputs during phases II or III were greater than during phase I (P<0.05). Exogenous motilin (0.3 microg/kg-hr, IV) stimulated 5-HT release into the duodenal lumen with peak values (P<0.05) during motilin-induced phase II and III. Gastroduodenal motor activity was not altered, however, during exogenous intraduodenal administration of 5-HT (300 ng/mL-min). CONCLUSIONS: 5-HT is released cyclically into the duodenal lumen in close temporal association with the MMC, but its physiologic significance in regulation of gastroduodenal motility is unknown.

Animals↗

PubMed1992

Effect of midecamycin acetate on gastrointestinal motility in humans.

The effect was studied on gastrointestinal motor activity of three different macrolides (erythromycin, roxithromycin and midecamycin acetate), administered by mouth in therapeutic doses. This placebo-controlled study was performed in 12 normal human subjects by means of intraluminal pressure measurements in the gastric antrum, duodenum and upper jejunum. In each subject, three manometries were done for 5 h in the interdigestive period and for 3 h postprandially. In the interdigestive period, midecamycin acetate did not affect the characteristics of the gastric migrating motor complex (MMC) and did not increase the number of antral contractions or the gastric motility index as compared to the placebo. Erythromycin and roxithromycin increased the number of antral contractions (24.5 +/- 11 versus 15.2 +/- 7 and 28.4 +/- 12 versus 14.9 +/- 5.9 respectively) and the motility index (4.05 +/- 0.5 versus 3.17 +/- 0.6 and 4.38 +/- 0.2. versus 3.64 +/- 0.7 respectively) as compared to the placebo. In the postprandial period, the number of antral contractions was not significantly increased by any of the three antibiotics. The postprandial antral motility index was not significantly increased by midecamycin acetate. In contrast, the postprandial antral motility indexes after erythromycin (4.4 +/- 0.5) and after roxithromycin (4.3 +/- 0.2) were significantly greater than after the placebo. In the upper small intestine, erythromycin elicited an increased number of phase-III-like activity events and roxithromycin shortened the MMC cycle length. Midecamycin acetate had no effect on interdigestive upper jejunal motility. The postprandial jejunal motor activity was not altered by any of the three antibiotics neither during the interdigestive nor the postprandial periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1998

Role of bile acids in duodenal migrating motor complexes in dogs.

Previous studies have suggested that enterohepatic circulation of bile acids is essential for regular cycling of duodenal migrating motor complexes (MMCs). The present study was an attempt to clarify the role of bile acids in the enterohepatic circulation system in initiating duodenal MMCs. Seven dogs underwent total external biliary diversion that resulted in the loss of MMCs originating from the duodenum. Sodium ursodeoxycholate (6 mg/kg/hr) was then given either through the portal vein or a peripheral vein, and motility of the gastrointestinal tract was serially recorded. When sodium ursodeoxycholate was given either through the portal vein or a peripheral vein during external biliary diversion, duodenal MMCs restarted. The cyclic change in plasma motilin levels during an MMC cycle as induced by sodium ursodeoxycholate was almost the same as in a normal MMC cycle. Total bile acid concentration in the portal vein changed cyclically with MMC cycles when bile flow was intact but did not change cyclically with MMC cycles restarted by intravenous bile salt infusion. Bile acid stimulation of putative receptors existing between the portal vein and intrahepatic bile ducts may be involved in initiating normal duodenal MMC cycles.

Animals↗

PubMed2003

Automated quantitative analysis of nocturnal jejunal motor activity identifies abnormalities in individuals and subgroups of patients with slow transit constipation.

OBJECTIVE: Small bowel dysmotility has previously been demonstrated in some patients with slow transit constipation (STC), suggesting a generalized intestinal disorder. However, no study has addressed whether the incidence of small intestinal dysfunction differs between subgroups of patients in this heterogeneous population. Using appropriate methodology, we aimed to determine prospectively the proportion of individuals with abnormal small bowel motility, and to assess whether heterogeneity in terms of pattern of colonic transit delay (based on (111)In diethylene-triamine-pentaacetic acid (DTPA) isotope scintigraphy), or mode of onset (based on clinical history) is of importance. METHODS: Thirty-seven patients with STC underwent 24-h ambulatory jejunal manometry; data were compared with those obtained in 38 healthy controls. Automated quantitative analysis of seven variables of the nocturnal migrating motor complex was performed, to assess whether differences existed between groups, and whether individual patients had evidence of small intestinal dysmotility, defined as two or more measures of migrating motor complex variables outside the normal range. Four variables differed significantly between STC patients and controls: in phase III, propagation was slower, duration was longer, and contraction amplitude was higher; in phase II, contraction frequency was increased. Seven of 24 patients with a generalized pattern of colonic transit delay had abnormal small bowel motility compared with none of 13 with a left-sided delay (p < 0.04). These included four patients with chronic idiopathic symptoms and three with acquired symptoms. Approximately one third of patients with a generalized delay in colonic transit had evidence of jejunal enteric neuromuscular dysfunction. Individual patients with a left-sided colonic delay did not satisfy the criteria for nocturnal small bowel dysmotility, but as a group, some differences were noted from controls. In contrast to previous reports, evidence of generalized enteric dysmotility may be present irrespective of the mode of onset.

Adolescent↗

PubMedDate not supplied

Semi-invasive laser-Doppler flowmetry technique. New application for recordings of hemodynamics in combination with manometry of human small intestine.

A small-bowel manometry tube was supplied with two single-fiber microprobes, which recorded blood flow in the proximal small intestine by the laser-Doppler flowmetry (LDF) technique. In all experiments, saline was infused intravenously as control during the first migrating motor complex (MMC) cycle, and a drug or another saline control given intravenously during the second MMC cycle. Recordings were performed during phase 1 of MMC, i.e. when motor pattern showed quiescence. Adrenaline increased blood perfusion values by 140% in proximal duodenum and 95% in distal duodenum. The alpha 2-adrenoceptor agonist clonidine decreased the corresponding values by 34 and 25%, respectively, while oxymetazoline decreased perfusion by 33 and 44% at the same levels. The beta-adrenoceptor agonist isoprenaline increased blood perfusion values by 172% in the proximal duodenum and 194% in the distal duodenum, whereas the antagonist propranolol decreased the corresponding values by 45 and 52%, respectively. In a separate group of subjects, propranolol was given after adrenaline. The increase in blood perfusion regularly seen after adrenaline was blocked after propranolol administration. In conclusion, our findings validate semi-invasive LDF technique for studies of hemodynamics in human small intestine under basal motor conditions and in drug-induced blood flow changes.

Adrenergic alpha-Agonists↗

PubMed1999

Effect of intravenous clarithromycin on interdigestive gastroduodenal motility of patients with functional dyspepsia and Helicobacter pylori gastritis.

Gastroduodenal motility of 16 patients complaining of functional dyspepsia and Helicobacter pylori gastritis was recorded by means of a low-compliance manometric system with four recording ports in the stomach and four in the duodenum. Clarithromycin (CLA) 250 mg (group A: 8 patients) or normal saline solution (group B: 8 patients) was infused intravenously randomly and in double-blind manner 30 min after the end of the first recorded activity front (AF) of the migrating motor complex or, in the absence of AFs, after 200 min of recording, continuing the recording until an AF was observed during the subsequent 200 min. CLA administration was followed by a typical gastroduodenal AF in a significantly higher number of patients than saline administration. In addition, the time-lag between the drug administration and the appearance of AFs was 22 min +/-7.4 (mean +/- SD), significantly shorter than after saline (109+/-56 min) and the CLA-related duodenal AFs showed a duration of 7.4 min +/-1.6 in group A, significantly longer than that of the spontaneous AFs (3.5 min +/-1), while in group B AF duration after saline was not significantly different from that of the spontaneous ones. In conclusion, clarithromycin is able to stimulate cyclic interdigestive gastroduodenal motility. This prokinetic property of clarithromycin is not unexpected because it is a macrolide like erythromycin, the prokinetic activity of which is well known, and could be utilized for therapeutic uses.

Adolescent↗

PubMed2001

Migrating motility complexes persist after severe traumatic shock in patients who tolerate enteral nutrition.

BACKGROUND: Postinjury small bowel ileus is poorly characterized and may be an important factor in intolerance to enteral nutrition (EN). We, therefore, placed jejunal manometry catheters in high-risk trauma patients. Our hypothesis was that the presence of "fasting migrating motility complex (MMC)" activity and conversion to a "fed pattern" at goal rate of EN would be present in those patients who tolerate jejunal feeding. METHODS: After obtaining baseline fasting manometry pressure tracings, jejunal feeding was advanced stepwise to a set goal while tolerance was monitored and intolerance was treated by a standard approach. RESULTS: Of the 10 study patients, 7 were able to be maintained on EN. Five (50%) had "fasting MMCs" and had good tolerance to early advancement of EN. The remaining five patients did not exhibit "fasting MMCs" and four had poor tolerance to early advancement of EN. Overall, nine patients reached goal rate of EN of which four converted to a "fed pattern." This, however, was not associated with later tolerance to EN. CONCLUSION: EN is feasible following severe traumatic shock. Surprisingly, half of the patients had fasting MMCs. This requires intact neural and motor function and was associated with good tolerance of early EN.

Adolescent↗

PubMed1996

Small intestinal motor abnormalities in patients with functional dyspepsia demonstrated by ambulatory manometry.

AIMS/METHODS: In 30 patients with functional dyspepsia and in 20 healthy volunteers, ambulatory duodenojejunal manometry was performed to examine the interdigestive and postprandial small intestinal motility patterns in relation to symptoms. RESULTS: In the fasting state, the number of migrating motor complex cycles mean (SEM) was significantly lower in patients, especially in patients with dysmotility-like dyspepsia, than in control subjects (3.8 (0.4), 2.6 (0.5), and 5.3 (0.7) cycles, respectively; p < 0.05), due to a longer duration of phase II. Non-propagated and retrogradely propagated phase III activity was more prevalent in patients than in control subjects (48% v 15%; p = 0.020). During phase II and after dinner no differences were found in contraction incidence, mean amplitude or motility index. However, 1 1/2 hours after completing breakfast the motility index was higher in patients at all three recording levels (p < 0.05). Burst activity was more prevalent in patients than in control subjects (22% v 6% of the subjects; p = 0.003). In 41% of the patients the symptom index was > 75%. CONCLUSIONS: These results suggest that small intestinal motor abnormalities, especially during fasting, participate in the pathogenesis of symptoms in patients with functional dyspepsia. Ambulatory manometry of the small intestine is a valuable tool to demonstrate these abnormalities in outpatients pursuing their daily activities.

Adult↗

PubMed1995

The migrating motor complex--the motor component of a cholinergic enteric secretomotor programme?

The role of cholinergic nerves in the cyclic activation of interdigestive motility and secretion was studied in 23 healthy volunteers. Net fluid transport in a distal duodenal segment and the release of pancreaticobiliary secretions into the duodenal lumen, were measured with a triple lumen perfusion technique. Interdigestive motor activity was recorded with a low-compliance pneumohydraulic system, and the transmural potential difference (PD) was measured as an on-line marker of electrogenic anion secretion. Transport parameters were related to the migrating motor complex (MMC) in the control situation and after the administration of atropine (0.01 mg kg-1 body wt, i.v.). The early part of the MMC cycle was characterized by low motor activity, low release of bile and pancreatic juice into the duodenal lumen, a slightly lumen positive transmural PD, and a non-significant net fluid absorption ('absorptive mode'). Under control conditions, motor activity and pancreaticobiliary secretions subsequently increased and there was a shift in net fluid transport and transmural PD in the secretory direction ('secretory mode'). Furthermore, there was a significant correlation between contraction frequency, a more lumen negative PD, and the magnitude of net fluid secretion. After the administration of atropine, the secretory mode was abolished, but there was still a significant correlation between contraction frequency and transmural PD. In conclusion, cholinergic neurones seem to mediate the shift from the absorptive to the secretory mode in the human distal duodenum. The antisecretory effect of atropine may be the result of inhibition of motilin release, reduced activation of tension-sensitive intramural secretory pathways, or blockade of cholinergic neurones to the secreting epithelium.

Adult↗

PubMed1996

Frequency of phasic wave contraction is variable during long-term sphincter of Oddi manometry.

OBJECTIVES: The sphincter of Oddi (SO) manometry via the transpapillary route is performed usually for a period of several minutes. To investigate whether there is a considerable variation in the manometric measurements of SO over a longer period of time, we have performed long-term manometry of SO via the transpapillary (n = 5) as well as the percutaneous (n = 7) routes. METHODS: Transpapillary manometry of SO was carried out by a conventional low-compliant continuously perfused technique. The location of the manometric catheter was maintained at the same level by observing the video monitor. SO manometry and the duodenal migrating motor complex (MMC) was simultaneously measured with a specially designed catheter via the percutaneous route. RESULTS: The mean recording time was 41 min (range 11-72 min). The frequency of phasic contractions of SO varied from 0 to 12/min. Throughout the entire recording period, high-frequency contractions (over 8/min) were noted 14.9% of the time. In the cases of percutaneous transductal SO manometry, the periods of high-frequency contractions coincided with phase III of duodenal MMC. The interval between the first high-frequency contractions and the second was 47 min. The mean duration of high-frequency contractions was 6 min and 42 s. There was no significant change in the amplitude, basal pressure, and contraction sequence among the various periods of frequencies. CONCLUSIONS: Long-term continuous recording of SO manometry via the transpapillary and percutaneous routes showed that the contraction frequency of SO was not constant and tachyoddia appeared periodically. In the interpretation of tachyoddia, it is necessary to consider the period of phase III of the duodenal MMC.

Bile Ducts, Intrahepatic↗

PubMed1993

Motility-related cyclic fluctuations of interdigestive gastric acid and bicarbonate secretion in man. A source of substantial variability in gastric secretion studies.

The relationship between interdigestive gastric motility and secretion was studied in eight healthy volunteers. Acid and bicarbonate output rates were measured with a high time resolution, using a perfusion system based on continuous registration of pH and PCO2 of gastric effluent. Antral pressure was measured by manometry. The total duration of the interdigestive motility cycle (time between two phase-III complexes) was 96 +/- 12 min (mean +/- SE). In late migrating motor complex phase II, acid output, bicarbonate output, and bile reflux increased significantly. Acid secretion reached a peak in association with motor phase III. The gastric lumen was then rapidly alkalinized; this phenomenon was due to a simultaneous decrease in acid secretion and a short-lasting (15 +/- 2 min, mean +/- SE) phasic increase in bicarbonate output, which was not associated with bile reflux (bilirubin). After these phase-III-related events both acid and bicarbonate output rates reached a relatively stable level during phase I and early phase II. This period of stability constituted 47 +/- 3% (acid) and 41 +/- 6% (bicarbonate, means +/- SE), respectively, of the cycle. The peak to base line output ratio was 6.6 +/- 1.2 (p < 0.001) for acid and 2.8 +/- 0.3 (p < 0.001) for bicarbonate (means +/- SE). The results show a marked variability in acid and bicarbonate output rates during the interdigestive motility cycle. The magnitude of this variability has previously been underestimated owing to poor time resolution of the secretion measurements. If not taken into account, these 'spontaneous' secretory variations may constitute a considerable source of error in gastric secretion studies.

Adult↗