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 271 records · Page 15Linked to original sources

PubMed1986

Jejunal myoelectrical activity in the conscious neonatal pig.

The purpose of this study was to define and quantify patterns of normal jejunal myoelectrical activity in the conscious neonatal pig. Twelve 3-day-old piglets were obtained from a local herd. At 7 days of age four bipolar Ag-AgCl electrodes were surgically implanted at 5 cm intervals on the jejunum. Piglets were divided into fed (n = 7) and fasted (n = 5) groups and a minimum of four daily recordings were made from each pig between 7 and 14 days of age. Slow wave and spike activity were seen in all animals. Slow waves occurred at a frequency of 17.0 +/- 0.3 cycles/min (c.p.m.) in fed and 16.8 +/- 0.2 c.p.m. in fasted piglets. Spike activity predominated, occurring in characteristic migrating myoelectrical complexes (m.m.c.s.) and occupying 79% of the recording time in fed and 73% in fasted piglets (P less than 0.05). The activity front (phase 3) of the m.m.c. recurred every 47.7 +/- 2.4 min in fed, and 50.9 +/- 2.3 min in fasted piglets. The m.m.c. periodicity in both groups was irregular, with a range of 4-145 min in fed, and 8-104 min in fasted piglets. Activity fronts lasted 4.8 +/- 0.1 min in fed and 4.4 +/- 0.1 min in fasted piglets. All piglets demonstrated intense, short (2.5-5.0 s), distinct bursts of intense spike activity (migrating action potential complexes, m.a.p.c.s.). These were rapidly conducted in an aboral direction at a velocity of 1.8 cm/s in fed, and 0.8 cm/s in fasted piglets (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗

PubMed1987

Small intestinal motility in fasted and postprandial states: effect of transient vagosympathetic blockade.

We investigated vagal control of the migrating myoelectric complex (MMC) and postprandial pattern of the canine small intestine. Gastric and small intestinal motility were monitored in six conscious dogs. The vagosympathetic nerves, previously isolated in bilateral skin loops, were blocked by cooling. To feed, a meat-based liquid food was infused by tube into the gastric fundus. MMC phases I, II, III, and IV were observed in the fasted state. On feeding, the fed pattern appeared quickly in the proximal small bowel but was delayed distally. Vagal blockade abolished all gastric contractions and spiking activity as well as the small bowel fed pattern. During vagal blockade, the small bowel exhibited MMC-like migrating bursts of spikes in both the fasted and fed states. The migration and cycling of these bursts were not significantly different from the MMC, but the duodenal and jejunal phase II was absent or shortened. On termination of vagal blockade, normal fasting or fed activity reappeared but with a delay in the fed pattern distally. We conclude: the ileum is the least sensitive to vagal blockade; the fasting vagal influence is exerted primarily on phases I and II of the duodenal and jejunal MMC; the fed pattern throughout the entire small bowel is normally dependent upon vagal integrity; the phase III-like bursts of activity seen during vagal blockade likely represents the intrinsic small bowel MMC, which is vagally independent.

Animals↗

PubMed1990

Small intestinal amyogenesia and dysmyogenesia induced by morphine and loperamide.

We studied the effects of morphine and loperamide on small bowel myoelectric and contractile activity in 12 conscious dogs. After initially producing premature migrating myoelectric complexes, both substances destabilized and obliterated electrical control activity (ECA). The obliteration of ECA occurred mainly in the proximal half of the small intestine. During ECA obliteration, the base line was almost flat at the usual amplification. At higher amplification, the base line exhibited irregular low level fluctuations that could not be related to electrical response activity (ERA) bursts or contractions. The mean time lag for obliteration of ECA in the proximal small intestine decreased at higher doses of morphine infusion. During the destabilization and obliteration of ECA, contractions and ERA bursts occurred in unusual patterns. The ERA bursts and contractions were generally discoordinated. However, in the proximal small intestine some contractions migrated rapidly and uninterrupted at 32 +/- 7 cm/s over long distances (124 +/- 24 cm). ECA destabilization and obliteration were reversed in approximately 15-30 min after the ingestion of a meal or intravenous administration of atropine, hexamethonium, or naloxone. We conclude that during the absence or destabilization of ECA, the ERA bursts and contractions occur in an uncontrolled manner. These two states were called "amyogenesia" and "dysmyogenesia," respectively. The unusual patterns of contractions during small intestinal amyogenesia and dysmyogenesia may be one of the factors in delayed intestinal transit produced by morphine and loperamide.

Animals↗

PubMed1989

Pacemaker activity in the proximal lower oesophageal sphincter of the dog.

1. The electrical and mechanical activities of different regions of the canine lower oesophageal sphincter were measured using the single sucrose gap technique. 2. Spontaneous electrical activity was found in the region 0-6 mm oral to the squamocolumnar border. 3. The electrical activity consisted of bursts of spikes superimposed on slow waves. The slow-wave frequency ranged from 0.6 to 5 min-1 in different muscle strips. 4. The slow wave-spike complex and associated contraction were insensitive to tetrodotoxin and atropine. 5. In the pacemaker region, electrical stimulation of intrinsic nerves evoked excitatory junction potentials (atropine sensitive), inhibitory junction potentials (non-adrenergic) and post-stimulus excitation. 6. Increase in the frequency of the slow waves was obtained by muscarinic receptor stimulation (carbachol 10(-7) M) and 10 mM-KCl. 7. The distal lower oesophageal sphincter exhibited a high basal tension but did not show spontaneous electrical activity and stimulation of intrinsic nerves revealed only non-cholinergic, non-adrenergic inhibition. 8. The electrical slow-wave activity observed in the proximal sphincter may constitute the control mechanism for the phasic nature of the contractile activity seen during both the postprandial period and phase III of the interdigestive migrating myoelectric complex. 9. The neural cholinergic activity present in the proximal lower oesophageal sphincter suggests the possibility of neural modulation of the myogenic control activity.

Action Potentials↗

PubMed1990

Effects of enteric neural defunctioning on small bowel motility.

In this study, we investigated the role of intrinsic nerves of the small intestine on phase III migration of the migrating myoelectric complex. Fasting myoelectric activity was recorded from the small bowel in chronically instrumented dogs. Once control experiments were completed, the animals were divided into two groups and were reoperated. In the first group of five dogs, a 1.5-g/dl aqueous solution of cobaltous chloride (shown to induce degeneration of intestinal intrinsic nerves) was infused close intra-arterially to perfuse a 15-cm segment of jejunum. In the second group of dogs, a catheter was implanted in a branch of the superior mesenteric artery supplying a 15-cm segment of intestine. Tetrodotoxin (0.3-1 micrograms/kg) was infused through the catheter just before the arrival of phase III activity in the perfused segment. Subsequent to the fifth postcobalt perfusion day, phase III traversed but did not occur in the cobalt-treated segment. When tetrodotoxin was injected through the catheter, spontaneous phasic myoelectric and contractile activities in the perfused jejunal segment were inhibited, but phase III migration was not blocked. These findings suggest 1) acute or chronic defunctioning of enteric nerves does not interrupt phase III migration, but 2) phase III expression is dependent on the integrity of intrinsic nerves.

Animals↗

PubMed1985

Canine cyclic motor activity of stomach and small bowel: the vagus is not the governor.

The influence of the vagus nerve on gastric cyclic motor activity and small bowel migrating motor complexes is controversial. Diaphragmatic vagesection does not alter their occurrence or periodicity, but cervical vagal cooling inhibits both gastric cyclic motor activity and duodenal phase II activity. We have clarified this contradictory data by reversible vagal cooling at the diaphragm level in 5 dogs implanted with strain gages and bipolar electrodes to record gastric and small intestinal cyclic activities. Circulation of coolant through an implanted convectional jacket surrounding the vagal trunks lowered jacket temperature to 2 degrees-8 degrees C and maintained this temperature for 3-5 h in each experiment. Vagal denervation during cooling was proven at the end of each trial by abolition of intravenous insulin-stimulated gastric contractions, which promptly appeared with warming. More than 90% of gastric motor cycles persisted during vagal cooling. The mean duration of gastric phase III activity was reduced during cooling but the mean period of gastric motor cycles was unchanged. Duodenal phase II and III activities were unchanged and migrated normally through the small bowel. We conclude that the vagus nerve may modulate the duration of gastric phase III activity but does not govern the initiation of gastric cyclic motor activity or the duration, period, and migration of small intestinal migrating myoelectric complexes. These findings concur with those after truncal vagectomy but are different from observations made with cervical vagal cooling.

Action Potentials↗

PubMed2005

Robust time delay estimation of bioelectric signals using least absolute deviation neural network.

The time delay estimation (TDE) is an important issue in modern signal processing and it has found extensive applications in the spatial propagation feature extraction of biomedical signals as well. Due to the extreme complexity and variability of the underlying systems, biomedical signals are usually nonstationary, unstable and even chaotic. Furthermore, due to the limitations of the measurement environments, biomedical signals are often noise-contaminated. Therefore, the TDE of biomedical signals is a challenging issue. A new TDE algorithm based on the least absolute deviation neural network (LADNN) and its application experiments are presented in this paper. The LADNN is the neural implementation of the least absolute deviation (LAD) optimization model, also called unconstrained minimum L1-norm model, with a theoretically proven global convergence. In the proposed LADNN-based TDE algorithm, a given signal is modeled using the moving average (MA) model. The MA parameters are estimated by using the LADNN and the time delay corresponds to the time index at which the MA coefficients have a peak. Due to the excellent features of L1-norm model superior to Lp-norm (p > 1) models in non-Gaussian noise environments or even in chaos, especially for signals that contain sharp transitions (such as biomedical signals with spiky series or motion artifacts) or chaotic dynamic processes, the LADNN-based TDE is more robust than the existing TDE algorithms based on wavelet-domain correlation and those based on higher-order spectra (HOS). Unlike these conventional methods, especially the current state-of-the-art HOS-based TDE, the LADNN-based method is free of the assumption that the signal is non-Gaussian and the noises are Gaussian and, thus, it is more applicable in real situations. Simulation experiments under three different noise environments, Gaussian, non-Gaussian and chaotic, are conducted to compare the proposed TDE method with the existing HOS-based method. Real application experiment is conducted to extract time delay information between every two adjacent channels of gastric myoelectrical activity (GMA) to assess the spatial propagation characteristics of GMA during different phases of the migrating myoelectrical complex (MMC).

Algorithms↗

PubMedDate not supplied

Anatomy, visualization and sampling of the biliary tree in animals and man.

Difficulties in obtaining proper bile samples are due to inaccessibility of the biliary tree and to distortions induced by sampling methods. One must be cognizant of the effects of diet on bile secretion and gallbladder motility. Experimental methods which interrupt the enterohepatic circulation or alter the intestinal migrating myoelectric complex induce spurious changes in bile flow and composition. Biliary tract pressure-flow relationships must be maintained or the gallbladder will be made functionless. Dead space errors lead to distortions unless studies are performed in the steady state, or dead space is measured and corrections are applied. Surgery has major effects on some parameters of interest, and animals should be allowed to recover when these are studied. The effect of the mixing of bile with other secretions in the duodenum must be considered when using bile-rich duodenal fluid. For some parameters of bile secretion, mixing is unimportant but for others, special precautions for handling bile and interpreting results are required.

Animals↗

PubMed1994

Intestinal pseudo-obstruction in adult spinal muscular atrophy.

A 42-year-old woman with negative family history had the insidious onset of weakness in her lower extremities 8 years before, in 1983. The disorder slowly progressed to include cramps and muscle twitches. The diagnosis of adult spinal muscular atrophy (SMA) was made when electromyography showed large rapidly firing motor unit-potentials, positive waves, and fibrillation potentials, and when muscle biopsy of the quadriceps revealed severe alterations consistent with neurogenic atrophy. The patient also had severe chronic constipation for many years. More recently she had developed unremitting diarrhea. Gastrointestinal studies showed no evidence of peristaltic contractions in the rectum, delayed gastric emptying, and abnormal jejunal manometry with altered propagation of the migrating myoelectrical complex.

Adult↗

PubMed1979

Computer program for intestinal spike bursts recognition.

A FORTRAN program has been developed for locating intestinal spike bursts and for estimating their strength. Tested against human scanning, the reliability rate was 92% and the misrecognition rate was 2.5%. This program was applied to the automatisation of the Migrating Myoelectric Complex analysis. A first method computed the percentage of Basic Electrical Rhythm (BER) cycles with superimposed spike bursts. A second one was based on the evaluation of spike bursts strength.

Animals↗

PubMed1978

Migrating electrical spike activity in the fasting human small intestine.

The purpose of the present investigation was to describe characteristics of migrating electrical phenomena in the human small intestine. A specially designed probe with several bipolar electrodes was placed in the upper small intestine of 5 normal, fasting volunteers for continuous registration of electrical spike potentials. A migrating myoelectric complex was observed resembling observations made previously in animal experiments. The active phase consisted of regular spike potentials propagating distally at a mean velocity of 12 cm/min, and a duration of about 5 min. In addition a "peristaltic rush" was observed consisting of spike potentials with a high amplitude, propagating distally at a mean velocity of 2 cm/sec and a duration of about 5 sec.

Action Potentials↗

PubMed1984

Involvement of serotonergic mechanisms in initiation of small intestine cyclic motor events.

Continuous mechanical and electrical activity recordings of the gastroduodenal junction and duodenum were performed in conscious sheep receiving pharmacologic agents delivered intraduodenally before and after nerve section. Sheep on a normal diet regimen exhibited cyclic periods of maximal activity (phase III of the migrating myoelectric complex) on the duodenum or in-series contractions on the duodenal bulb recurring at a frequency of 13/24 hr and more after nerve section. Among the variety of agents triggering in intact animals premature phases of maximal activity, methysergide, when administered locally, was found to increase the number of complexes to a frequency of 24/24 hr, even when extrinsic nerve supply was removed. The results suggest that in the ovine model the mechanism of cycling of the motor events involved serotonergic myenteric neurons located in the duodenal bulb. The data were consistent with the regulation of the enteric biological clock via 5HT neural receptors mediating inhibition.

Animals↗

PubMed1981

Insulin and myoelectric activity of the small intestine of the pig.

The effect of insulin on the myoelectric activity of the small intestine was determined in conscious pigs. Animals were implanted with electrodes along the small intestine, a strain gage on the stomach and catheters in both saphenous arteries. Feeding modified the migrating myoelectric complex (MMC), a cyclic pattern of action potential activity of the small intestine characteristic of fasting. The first period of regular spiking activity (RSA) on the duodenum after feeding was delayed and was not followed by quiescence. Plasma insulin and glucose concentrations during the first three MMC after feeding were highest just before periods of duodenal RSA. Injection or infusion of insulin into fasted pigs with production of hypoglycemia caused disruption of stomach motility and duodenal electrical activity. The duodenal MMC was not altered when glucose to prevent hypoglycemia was infused together with insulin or when glucose was infused alone. These studies suggest that insulin is not directly responsible for the postprandial modification of MMC activity as insulin infusions only modify the MMC when hypoglycemia occurs.

Action Potentials↗

PubMed1984

Effects of central and peripheral administration of dopamine on pattern of intestinal motility in dogs.

The central vs peripheral effects of dopamine on the motility pattern of the small intestine were investigated by electromyography in four conscious dogs, chronically fitted with transparietal duodenal and jejunal electrodes. In the fasted dog intracerebroventricular administration of dopamine (10 micrograms/kg) increased the duration of the interval between two consecutive migrating myoelectric complexes (MMC) while the intravenous administration at a 10-fold higher dose induced in 37.5% of trials a phase of regular spiking activity propagated over the duodenum and the jejunum. When dopamine was centrally administered 1 hr before a daily meal, the duration of the postprandial disruption of the MMC pattern was significantly (P less than 0.01) reduced from 9.4 +/- 1.8 to 3.2 +/- 1.3 hr at the level of the duodenum. Peripheral administration of dopamine did not modify the duration of the postprandial disruption. All of the central and peripheral effects persisted after vagotomy. It is concluded that in the dog dopamine acts centrally to modify the food-induced disruption of the MMC pattern and the frequency of the interdigestive myoelectric complexes.

Animals↗

PubMed1980

Effect of metoclopramide on interdigestive myoelectric activity in the conscious dog.

The effect of two-hour infusions of metoclopramide at five different doses on interdigestive intestinal electrical activity was studied in four conscious fasting dogs. Spike activity during the infusions was quantitatively compared with activity during preceding and following periods of saline infusion. The effect of the drug was the enhancement of spike activity during migrating myoelectric complexes (MMC) without disruption of the fasting pattern; the effect was most marked in the proximal small intestinal and diminished distally. As in other published studies with metoclopramide, its effects were variable and not dose dependent. The enhancement of the MMC by an exogenous stimulus, not previously reported, provides indirect evidence for cholinergic mediation of cyclical motor activity, and also suggests a rational basis for therapy.

Animals↗

PubMed1980

Gastrointestinal myoelectric activity disturbances in gastric ulcer disease in rats and dogs.

Electrical spiking activity of the antrum, duodenum, and jejunum was recorded from chronically implanted electrodes in rats and dogs. Gastric ulceration was induced by physical restraint in rats and by indomethacin treatment in dogs. In rats, restraint caused a 30% reduction of intestinal slow-wave frequency. After restraint the basal electrical rhythm (BER) returned to normal but in ulcerated rats the amplitude of spike potentials decreased and the migrating myoelectric complexes (MMC) of fasting were abolished by a continuous irregular spiking activity. In dogs, the amplitude of spiking activity progressively declined after the 6th day of indomethacin treatment. The frquency of the canine MMCs during the interdigestive state decreased from 0.6 to 0.2 per hour in ulceraed dog. The duration of the postprandial disorganization increased from 8 to 20 hr. It is concluded that, independent of the ulcerogenic factors, gastric ulceration induced both a reduction of the amplitude of the intestinal spiking activity and disruption of the MMCs.

Animals↗

PubMed1986

Cyclic motor activity and trophicity after jejunal resection and bypass in rats.

The aim of the study was to examine the changes in intestinal motility induced by an extensive jejunal resection and bypass in rats using an electromyographic technique. The relationship, if any, between the development of motility and adaptive modifications of intestinal trophicity was also studied. A massive jejunal resection, preserving a 7-cm segment distal to the ligament of Treitz, was performed in one group of animals. In a second group, the jejunum was bypassed as a self-emptying blind loop. Two sham-operated groups underwent transection and reanastomosis on the proximal jejunum or ileum. Electromyographic activity was studied at the 10th and 30th postoperative days by means of electrodes implanted throughout the remaining or bypassed bowel and was expressed by means of the pattern of recurrence of the migrating myoelectric complex (MMC). After a month, the animals were sacrificed. Mucosal and muscular wet weight and protein content (mg/cm) of the intestine were then determined. The results showed that 10 days after the jejunal resection in the fasting state, MMC cycle duration is different in the remaining jejunum and in the ileum. However, the distribution of MMC phases in the jejunum was modified and was similar to the one in the ileum. Thirty days after resection, MMC cycle duration, as well as phase distribution in the remaining jejunum, resemble the MMC patterns in the ileum. These changes were not observed after bypass. After the return of MMCs after postprandial inhibition produced by a meal, MMC duration in the ileum was greatly decreased until a month after jejunal resection. In contrast, the jejunal bypass did not produce this modification.

Action Potentials↗

PubMed1989

Gastrointestinal myoelectric activity in an infant with congenital idiopathic motility disorder.

We investigated myoelectric activity in an 8-month-old male who presented with a perinatal bowel obstruction, duodenal band, congenital short small intestine, and persistent feeding intolerance. Serosal electrodes were surgically implanted on stomach, duodenum, and jejunum during Nissen fundoplication and ileostomy. A 5-cm ileal specimen was taken for in vitro studies. Spontaneous migrating myoelectric complexes (MMC) were present in stomach and small intestine. Bethanechol increased electrical response activity (ERA) in stomach and duodenum. Morphine induced intense ERA and distinct phase III activity. Pentagastrin infusion did not disrupt MMC cycling. Feeding disrupted MMC complex cycling 30-40 min after the meal. Metoclopramide before feeding delayed disruption of the MMC cycling after the feeding. Intermittent gastric arrhythmias were present after the fifth postoperative day. In vitro muscle strips showed spontaneous contractions and electrical control activity (ECA). Bethanechol, McNeil A-343, motilin, and cholecystokinin induced contractions, but pentagastrin had no effect. We conclude that in spite of a major clinical motility dysfunction, several of our findings were normal. The abnormalities include short MMC period, absence of disruption of MMC by pentagastrin, and gastric arrhythmias.

Bethanechol↗