Peripheral pacemakers and patterns of slow wave propagation in the canine small intestine in vivo

2005 ◽  
Vol 83 (11) ◽  
pp. 1031-1043 ◽  
Author(s):  
Wim J.E.P Lammers ◽  
Luc Ver Donck ◽  
Jan A.J Schuurkes ◽  
Betty Stephen
Keyword(s):  
Wave Propagation ◽  
Small Intestine ◽  
Slow Wave ◽  
Electrode Array ◽  
Canine Model ◽  
Slow Waves ◽  
Velocity Amplitude ◽  
Local Site ◽  
Propagation Pattern

In an anesthetized, open-abdomen, canine model, the propagation pattern of the slow wave and its direction, velocity, amplitude, and frequency were investigated in the small intestine of 8 dogs. Electrical recordings were made using a 240-electrode array from 5 different sites, spanning the length of the small intestine. The majority of slow waves propagated uniformly and aborally (84%). In several cases, however, other patterns were found including propagation in the oral direction (11%) and propagation block (2%). In addition, in 69 cases (3%), a slow wave was initiated at a local site beneath the electrode array. Such peripheral pacemakers were found throughout the entire intestine. The frequency, velocity, and amplitude of slow waves were highest in the duodenum and gradually declined along the intestine reaching lowest values in the distal ileum (from 17.4 ± 1.7 c/min to 12.2 ± 0.7 c/min; 10.5 ± 2.4 cm/s to 0.8 ± 0.2 cm/s, and 1.20 ± 0.35 mV to 0.31 ± 0.10 mV, respectively; all p < 0.001). Consequently, the wavelength of the slow wave was strongly reduced from 36.4 ± 0.8 cm to 3.7 ± 0.1 cm (p < 0.001). We conclude that the patterns of slow wave propagation are usually, though not always, uniform in the canine small intestine and that the gradient in the wavelength will influence the patterns of local contractions.Key words: slow waves, conduction velocity, peripheral pacemakers, wavelength.

Longitudinal and circumferential spike patches in the canine small intestine in vivo

2003 ◽  
Vol 285 (5) ◽  
pp. G1014-G1027 ◽  
Author(s):  
Wim J. E. P. Lammers ◽  
Luc Ver Donck ◽  
Jan A. J. Schuurkes ◽  
Betty Stephen
Keyword(s):  
Small Intestine ◽  
Slow Wave ◽  
Electrode Array ◽  
Longitudinal Direction ◽  
Canine Model ◽  
Interelectrode Distance ◽  
Intestinal Tube ◽  
Antimesenteric Border ◽  
Local Patterns

In an open-abdominal anesthetized and fasted canine model of the intact small intestine, the presence, location, shape, and frequency of spike patches were investigated. Recordings were performed with a 240-electrode array (24 × 10, 2-mm interelectrode distance) from several sites sequentially, spanning the whole length of the small intestine. All 240 electrograms were recorded simultaneously during periods of 5 min and were analyzed to reconstruct the origin and propagation of individual spikes. At every level in the small intestine, spikes propagated in all directions before stopping abruptly, thereby activating a circumscribed area termed a “patch.” Two types of spikes were found: longitudinal spikes, which propagated predominantly in the longitudinal direction and occurred most often in the duodenum, and a second type, circumferential spikes, which propagated predominantly in the circular direction and occurred much more frequently in the jejunum and ileum. Circumferential spikes conducted faster than longitudinal spikes (17 ± 6 and 7 ± 2 cm/s, respectively; P < 0.001). Circumferential spikes originated in >90% of all cases from the antimesenteric border, whereas longitudinal spikes were initiated all around the circumference of the intestinal tube. Finally, the spatial sequence of spike patches after the slow wave was very irregular in the upper part of the intestine but much more regular in the lower part. In conclusion, spikes and spike patches occur throughout the small intestine, whereas their type, sites of origin, extent of propagation, and frequencies of occurrence differ along the length of the small intestine, suggesting differences in local patterns of motility.

scholarly journals Abnormal gastric slow waves in patients with functional dyspepsia assessed by multichannel electrogastrography

2001 ◽  
Vol 280 (6) ◽  
pp. G1370-G1375 ◽  
Author(s):  
Xuemei Lin ◽  
Jiande Z. Chen
Keyword(s):  
Wave Propagation ◽  
Functional Dyspepsia ◽  
Slow Wave ◽  
Single Channel ◽  
Slow Waves ◽  
Lower Percentage ◽  
Healthy Controls ◽  
Fasting State ◽  
Gastric Slow Wave ◽  
Gastric Slow Waves

The aim of this study was to utilize multichannel electrogastrography to investigate whether patients with functional dyspepsia had impaired propagation or coordination of gastric slow waves in the fasting state compared with healthy controls. The study was performed in 10 patients with functional dyspepsia and 11 healthy subjects. Gastric myoelectrical activity was measured by using surface electrogastrography with a specially designed four-channel device. The study was performed for 30 min or more in the fasting state. Special computer programs were developed for the computation of the propagation and coupling of the gastric slow wave. It was found that, compared with the healthy controls, the patients showed a significantly lower percentage of slow wave propagation (58.0 ± 8.9 vs. 89.9 ± 2.6%, P < 0.002) and a significantly lower percentage of slow wave coupling (46.9 ± 4.4 vs. 61.5 ± 6.9%, P < 0.04). In addition, the patients showed inconsistencies in the frequency and regularity of the gastric slow wave among the four-channel electrogastrograms (EGGs). It was concluded that patients with functional dyspepsia have impaired slow wave propagation and coupling. Multichannel EGG has more information than single-channel EGG for the detection of gastric myoelectrical abnormalities.

Effect of secretin on electrical activity of small intestine

1975 ◽  
Vol 229 (2) ◽  
pp. 484-488 ◽  
Author(s):  
AK Mukhopadhyay ◽  
LR Johnson ◽  
EM Copeland ◽  
NW Weisbrodt
Keyword(s):  
Small Intestine ◽  
Small Bowel ◽  
Electrical Activity ◽  
Slow Wave ◽  
Intravenous Infusion ◽  
Action Potentials ◽  
Slow Waves ◽  
Wave Frequency ◽  
Conscious Dogs ◽  
Total Percentage

The effect of intravenously administered secretin (0.5, 2.0, 6.0 U/kg-h) and intraduodenal acidification (13.2 meq/h HCl) on the electrical activity of the small bowel of three conscious dogs with gastric and duodenal cannulas was observed. Electrical activity was recorded in fasted as well as fed conditions through silver wire electrodes implanted along the entire length of the small bowel. Intravenous infusion of secretin in all dosages and in all dogs delayed the onset of the interdigestive myoelectric complex and reduced the total percentage of slow waves with superimposed spike potentials. Intraduodenal acidification also inhibited the interdigestive myoelectric complex, which developed incompletely with fewer action potentials on slow waves. Secretin did not produce any alteration in the fed pattern of activity, slow-wave frequency, or the caudal migration of the interdigestive myoelectric complex. The present study indicates that the nuerohumoral mechanisms responsible for initiation of the interdigestive myoelectric complex may be different from those responsible for its caudal migration.

Myogenic mechanism for peristalsis in the cat esophagus

1999 ◽  
Vol 277 (2) ◽  
pp. G306-G313 ◽  
Author(s):  
Harold G. Preiksaitis ◽  
Nicholas E. Diamant
Keyword(s):  
Muscle Contraction ◽  
Slow Wave ◽  
Circular Muscle ◽  
Smooth Muscle Contraction ◽  
Slow Waves ◽  
Mechanical Activity ◽  
Control Mechanisms ◽  
Slow Wave Oscillations

A myogenic control system (MCS) is a fundamental determinant of peristalsis in the stomach, small bowel, and colon. In the esophagus, attention has focused on neuronal control, the potential for a MCS receiving less attention. The myogenic properties of the cat esophagus were studied in vitro with and without nerves blocked by 1 μM TTX. Muscle contraction was recorded, while electrical activity was monitored by suction electrodes. Spontaneous, nonperistaltic, electrical, and mechanical activity was seen in the longitudinal muscle and persisted after TTX. Spontaneous circular muscle activity was minimal, and peristalsis was not observed without pharmacological activation. Direct electrical stimulation (ES) in the presence of bethanechol or tetraethylammonium chloride (TEA) produced slow-wave oscillations and spike potentials accompanying smooth muscle contraction that progressed along the esophagus. Increased concentrations of either drug in the presence of TTX produced slow waves and spike discharges, accompanied by peristalsis in 5 of 8 TEA- and 2 of 11 bethanechol-stimulated preparations without ES. Depolarization of the muscle by increasing K+ concentration also produced slow waves but no peristalsis. We conclude that the MCS in the esophagus requires specific activation and is manifest by slow-wave oscillations of the membrane potential, which appear to be necessary, but are not sufficient for myogenic peristalsis. In vivo, additional control mechanisms are likely supplied by nerves.

Slow waves actively propagate at submucosal surface of circular layer in canine colon

1990 ◽  
Vol 259 (2) ◽  
pp. G258-G263 ◽  
Author(s):  
K. M. Sanders ◽  
R. Stevens ◽  
E. Burke ◽  
S. W. Ward
Keyword(s):  
Wave Propagation ◽  
Slow Wave ◽  
Proximal Colon ◽  
Slow Waves ◽  
Pacemaker Cells ◽  
Transverse Axis ◽  
Active Mechanism ◽  
Conduction Velocities ◽  
Circular Layer ◽  
Thin Band

Colonic slow waves originate from pacemaker cells along the submucosal surface of the circular layer in the dog proximal colon. These events propagate in a nonregenerative manner into the bulk of the circular layer. Conduction velocities consistent with an active mechanism for slow-wave propagation in the longitudinal and circumferential axes of the colon have been reported. Experiments were performed using intracellular recording techniques on canine colonic muscles to determine the regenerative pathway for slow-wave propagation. In a thin band of muscle adjacent to the submucosal border of the circular layer, slow-wave amplitude was independent of distance from a pacing source, and events propagated at a rate of approximately 17 mm/s in the long axis of the circular fibers and 6 mm/s in the transverse axis of the circular fibers. These findings suggest that slow waves propagate in a regenerative manner in this region. Slow waves decayed as they conducted through regions from which the pacemaker cells had been removed with space constants of a few millimeters. Thus the integrity of the thin pacemaker region along submucosal surface is critical for propagation of slow waves and the organization of motility into segmental contractions.

Waxing and waning of slow waves in intestinal musculature

1986 ◽  
Vol 250 (1) ◽  
pp. G28-G34 ◽  
Author(s):  
N. Suzuki ◽  
C. L. Prosser ◽  
W. DeVos
Keyword(s):  
Slow Wave ◽  
Electrical Coupling ◽  
Longitudinal Axis ◽  
Slow Waves ◽  
Rabbit Intestine ◽  
Rabbit Small Intestine ◽  
Intestinal Musculature ◽  
Pattern Of Variation

Electrical slow waves from cat or rabbit small intestine show more variability when recorded in vivo than in vitro. One pattern of variation is waxing and waning of amplitude, or "spindling," during which two rhythms of slightly different frequency come in and out of phase. Fourier power analyses of slow waves during spindles show two frequency peaks of slow waves differing by 0.4-5.0 waves/min and corresponding to measured spindle durations of 12-150 s. Spindles can be induced in vitro in rabbit intestine by K depolarization of approximately 15 mV. Histograms of intracellular recordings of slow nonspindling waves show variation of 0.5-1.0 s on either side of a mean slow wave duration. Spindles are abolished by treatments that reduce electrical coupling between cells, e.g., hypertonic sucrose or lowered pH, but changes in calcium do not alter spindles. Simultaneous recordings by two electrodes in the longitudinal axis show synchrony of spindles at 2- to 3-mm but not at 5-mm separation and synchrony circumferentially to the opposite side of a segment. Contractions, both in vivo and in vitro, correspond with electrical spindles in amplitude. Spindle durations were significantly shorter in vivo than in vitro, indicating a significantly greater difference in vivo in the competing frequencies at the point of recording (P less than 0.01). Three conditions favoring waxing and waning are slight depolarization, variation in slow wave frequency at a point, and electrotonic coupling between muscle fibers. Spindles provide for rhythms of contractions of a 1- to 2-min period.

S2067 ICC and Slow Wave Propagation in the Small Intestine of Diabetic Rats

2010 ◽  
Vol 138 (5) ◽  
pp. S-313
Author(s):  
Wim Lammers ◽  
Hanifa M. Al-Bloushi ◽  
Shaikha Al-Eisaei ◽  
Fatima Al-Dhaheri ◽  
Betty Stephen ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Small Intestine ◽  
Slow Wave ◽  
Diabetic Rats

scholarly journals High-resolution mapping of gastric slow-wave recovery profiles: biophysical model, methodology, and demonstration of applications

2017 ◽  
Vol 313 (3) ◽  
pp. G265-G276 ◽  
Author(s):  
N. Paskaranandavadivel ◽  
L. K. Cheng ◽  
P. Du ◽  
J. M. Rogers ◽  
G. O’Grady
Keyword(s):  
Wave Propagation ◽  
Wavelet Transform ◽  
High Resolution ◽  
Slow Wave ◽  
Recovery Phase ◽  
Slow Waves ◽  
Gastric Slow Wave ◽  
High Resolution Mapping ◽  
Resolution Mapping ◽  
Extracellular Potentials

Slow waves play a central role in coordinating gastric motor activity. High-resolution mapping of extracellular potentials from the stomach provides spatiotemporal detail on normal and dysrhythmic slow-wave patterns. All mapping studies to date have focused exclusively on tissue activation; however, the recovery phase contains vital information on repolarization heterogeneity, the excitable gap, and refractory tail interactions but has not been investigated. Here, we report a method to identify the recovery phase in slow-wave mapping data. We first developed a mathematical model of unipolar extracellular potentials that result from slow-wave propagation. These simulations showed that tissue repolarization in such a signal is defined by the steepest upstroke beyond the activation phase (activation was defined by accepted convention as the steepest downstroke). Next, we mapped slow-wave propagation in anesthetized pigs by recording unipolar extracellular potentials from a high-resolution array of electrodes on the serosal surface. Following the simulation result, a wavelet transform technique was applied to detect repolarization in each signal by finding the maximum positive slope beyond activation. Activation-recovery (ARi) and recovery-activation (RAi) intervals were then computed. We hypothesized that these measurements of recovery profile would differ for slow waves recorded during normal and spatially dysrhythmic propagation. We found that the ARi of normal activity was greater than dysrhythmic activity (5.1 ± 0.8 vs. 3.8 ± 0.7 s; P < 0.05), whereas RAi was lower (9.7 ± 1.3 vs. 12.2 ± 2.5 s; P < 0.05). During normal propagation, RAi and ARi were linearly related with negative unit slope indicating entrainment of the entire mapped region. This relationship was weakened during dysrhythmia (slope: −0.96 ± 0.2 vs −0.71 ± 0.3; P < 0.05). NEW & NOTEWORTHY The theoretical basis of the extracellular gastric slow-wave recovery phase was defined using mathematical modeling. A novel technique utilizing the wavelet transform was developed and validated to detect the extracellular slow-wave recovery phase. In dysrhythmic wavefronts, the activation-to-recovery interval (ARi) was shorter and recovery-to-activation interval (RAi) was longer compared with normal wavefronts. During normal activation, RAi vs. ARi had a slope of −1, whereas the weakening of the slope indicated a dysrhythmic propagation.

Mechanisms underlying nutrient-induced segmentation in isolated guinea pig small intestine

2007 ◽  
Vol 292 (4) ◽  
pp. G1162-G1172 ◽  
Author(s):  
R. M. Gwynne ◽  
J. C. Bornstein
Keyword(s):  
Small Intestine ◽  
Guinea Pig ◽  
Motor Neurons ◽  
Slow Wave ◽  
Neural Circuit ◽  
Circular Muscle ◽  
Decanoic Acid ◽  
Slow Waves ◽  
Longitudinal Position

Mechanisms underlying nutrient-induced segmentation within the gut are not well understood. We have shown that decanoic acid and some amino acids induce neurally dependent segmentation in guinea pig small intestine in vitro. This study examined the neural mechanisms underlying segmentation in the circular muscle and whether the timing of segmentation contractions also depends on slow waves. Decanoic acid (1 mM) was infused into the lumen of guinea pig duodenum and jejunum. Video imaging was used to monitor intestinal diameter as a function of both longitudinal position and time. Circular muscle electrical activity was recorded by using suction electrodes. Recordings from sites of segmenting contractions showed they are always associated with excitatory junction potentials leading to action potentials. Recordings from sites oral and anal to segmenting contractions revealed inhibitory junction potentials that were time locked to those contractions. Slow waves were never observed underlying segmenting contractions. In paralyzed preparations, intracellular recording revealed that slow-wave frequency was highly consistent at 19.5 (SD 1.4) cycles per minute (c/min) in duodenum and 16.6 (SD 1.1) c/min in jejunum. By contrast, the frequencies of segmenting contractions varied widely (duodenum: 3.6–28.8 c/min, median 10.8 c/min; jejunum: 3.0–27.0 c/min, median 7.8 c/min) and sometimes exceeded slow-wave frequencies for that region. Thus nutrient-induced segmentation contractions in guinea pig small intestine do not depend on slow-wave activity. Rather they result from a neural circuit producing rhythmic localized activity in excitatory motor neurons, while simultaneously activating surrounding inhibitory motor neurons.

scholarly journals Conditional genetic deletion of Ano1 in interstitial cells of Cajal impairs Ca2+ transients and slow waves in adult mouse small intestine

2017 ◽  
Vol 312 (3) ◽  
pp. G228-G245 ◽  
Author(s):  
John Malysz ◽  
Simon J. Gibbons ◽  
Siva A. Saravanaperumal ◽  
Peng Du ◽  
Seth T. Eisenman ◽  
...  
Keyword(s):  
Small Intestine ◽  
Slow Wave ◽  
Interstitial Cells Of Cajal ◽  
Adult Mouse ◽  
Rank Order ◽  
Interstitial Cells ◽  
Slow Waves ◽  
Functional Reserve ◽  
Mouse Small Intestine ◽  
Cells Of Cajal

Myenteric plexus interstitial cells of Cajal (ICC-MY) in the small intestine are Kit+ electrical pacemakers that express the Ano1/TMEM16A Ca2+-activated Cl– channel, whose functions in the gastrointestinal tract remain incompletely understood. In this study, an inducible Cre-LoxP-based approach was used to advance the understanding of Ano1 in ICC-MY of adult mouse small intestine. KitCreERT2/+;Ano1Fl/Fl mice were treated with tamoxifen or vehicle, and small intestines (mucosa free) were examined. Quantitative RT-PCR demonstrated ~50% reduction in Ano1 mRNA in intestines of conditional knockouts (cKOs) compared with vehicle-treated controls. Whole mount immunohistochemistry showed a mosaic/patchy pattern loss of Ano1 protein in ICC networks. Ca2+ transients in ICC-MY network of cKOs displayed reduced duration compared with highly synchronized controls and showed synchronized and desynchronized profiles. When matched, the rank order for Ano1 expression in Ca2+ signal imaged fields of view was as follows: vehicle controls>>>cKO(synchronized)>cKO(desynchronized). Maintenance of Ca2+ transients’ synchronicity despite high loss of Ano1 indicates a large functional reserve of Ano1 in the ICC-MY network. Slow waves in cKOs displayed reduced duration and increased inter-slow-wave interval and occurred in regular- and irregular-amplitude oscillating patterns. The latter activity suggested ongoing interaction by independent interacting oscillators. Lack of slow waves and depolarization, previously reported for neonatal constitutive knockouts, were also seen. In summary, Ano1 in adults regulates gastrointestinal function by determining Ca2+ transients and electrical activity depending on the level of Ano1 expression. Partial Ano1 loss results in Ca2+ transients and slow waves displaying reduced duration, while complete and widespread absence of Ano1 in ICC-MY causes lack of slow wave and desynchronized Ca2+ transients. NEW & NOTEWORTHY The Ca2+-activated Cl− channel, Ano1, in interstitial cells of Cajal (ICC) is necessary for normal gastrointestinal motility. We knocked out Ano1 to varying degrees in ICC of adult mice. Partial knockout of Ano1 shortened the widths of electrical slow waves and Ca2+ transients in myenteric ICC but Ca2+ transient synchronicity was preserved. Near-complete knockout was necessary for transient desynchronization and loss of slow waves, indicating a large functional reserve of Ano1 in ICC. View this article's corresponding video summary at https://youtu.be/cyPtDP0KLY4 .

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