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

Lammers, Wim J. E. P.; Donck, Luc Ver; Schuurkes, J. A. J.; Stephen, Betty

doi:10.1152/ajpgi.00138.2003

Cited by 36 publications

(53 citation statements)

References 27 publications

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“…8 and 9). This is analogous to the situation in the small intestine where spike velocity is much faster than that of the underlying slow waves (22).…”

Section: Discussionmentioning

confidence: 56%

“…Crane and Martin (4), in their laparoscopic study of myometrial contractions in rats in estrus, mentioned that circular contractions often seemed to move along the antimesometrial border and that, after implantation of the embryos, circular contractions became more prominent than longitudinal ones (3). This origin and orientation is also present in the initiation and propagation of circular spikes in the canine small intestine (22). It would seem that this Fig.…”

Section: Discussionmentioning

confidence: 62%

“…In both cases, the depolarization induced by the (slow) waves initiate the opening of L-calcium channels leading to the occurrence of spikes. In the intestines, it is possible to record both slow waves and spikes with extracellular electrodes, and this made it possible to reconstruct the pattern of propagation of both signals and to study the complex interaction between these two electrical waveforms (22).…”

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confidence: 99%

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Patterns of electrical propagation in the intact pregnant guinea pig uterus

Lammers¹,

Mirghani²,

Stephen³

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

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Previous studies have reported on propagation of individual spikes in isolated segments of the pregnant uterus, but there is no information on patterns of spike propagation in the intact organ. There is also no information on propagation of myometrial burst. The aim of this study was to record, at high resolution, patterns of propagation of electrical activities in the pregnant uterus. Sixteen timed-pregnant guinea pigs were euthanized at term, and their uteruses isolated. Fetuses were removed and replaced by an equal amount of Tyrode. A 240-electrode array was positioned at various locations along the organ, all signals were recorded simultaneously, and the electrical propagations were reconstructed. In the intact pregnant uterus at term, spikes propagated with high velocity in longitudinal (6.8 Ϯ 2.4 cm/s) and slower velocity in circular direction (2.8 Ϯ 1.0 cm/s; P Ͻ 0.01). Direction of propagation and frequency of activity were highly variable but showed similar patterns at the ovary or cervical end and along the anterior, posterior, and antimesometrial borders. Along mesometrium, spike propagation was sparse and fractionated. Migration of burst (0.6 Ϯ 0.4 cm/s) was significantly much slower than that of individual spikes (P Ͻ 0.001). Initial burst activity was located at variable locations along the ovarial end of the antimesometrial border, while the latest excitation occurred at the cervical end (1.2 Ϯ 0.9 min). In conclusion, high resolution electrical mapping of the intact pregnant uterus reveals fundamental properties in spatial and temporal patterns of spike and burst propagation that determine the contraction of the organ. spikes; myometrial burst migration ELECTRICAL ACTIVITY in the pregnant myometrium is characterized by phasic bursts of action potentials (spikes), which could be based on cyclic changes in transmembrane potential (24). Cyclic changes in potential resemble in some respects slow waves in the intestines and presumably propagate through the myometrium, similar to the propagation of the intestinal slow waves. In both cases, the depolarization induced by the (slow) waves initiate the opening of L-calcium channels leading to the occurrence of spikes. In the intestines, it is possible to record both slow waves and spikes with extracellular electrodes, and this made it possible to reconstruct the pattern of propagation of both signals and to study the complex interaction between these two electrical waveforms (22).In the myometrium, the basic electrical wave is too slow or its magnitude too small to be recorded extracellularly (9). The spikes, however, are visible in extracellular recordings and this led to several studies on their behavior. Miller et al. (25) analyzed spike propagation in pregnant uterine segments that were 3 ϫ 1 cm in size and showed that velocity in the longitudinal direction was much faster than in the circumferential direction. Lammers et al. (20) found similar results in equally small segments (8 ϫ 2 cm). Most of these studies were performed on isolated segments of...

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“…8 and 9). This is analogous to the situation in the small intestine where spike velocity is much faster than that of the underlying slow waves (22).…”

Section: Discussionmentioning

confidence: 56%

Section: Discussionmentioning

confidence: 62%

mentioning

confidence: 99%

See 1 more Smart Citation

Patterns of electrical propagation in the intact pregnant guinea pig uterus

Lammers¹,

Mirghani²,

Stephen³

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Evidence that spike propagation can decrement in this fashion has been seen in many smooth muscle types. [8][9][10][11] We could not be certain that we were recording from smooth muscle cells but it is unlikely that we were recording from either endothelial cells (they are very thin and are not known to exhibit spontaneous activity of the type described) or from pacemaker cells since there are very few of these (although we could not exclude this possibility and indeed this may account in part for the variability we observed).…”

Section: Discussionmentioning

confidence: 92%

Spontaneous Electrical Activity in Sheep Mesenteric Lymphatics

Beckett

Hollywood²,

Thornbury³

et al. 2007

Lymphatic Research and Biology

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Background: It has recently become apparent that the lymph pump is an electrical entity that rivals the heart in complexity. Many interesting currents have been demonstrated by voltage clamping isolated lymphatic smooth muscle cells, but until now the role of these currents in the intact syncitium has not been studied.Methods and Results: Intracellular microelectrode recordings were made from smooth muscle of sheep mesenteric lymphatics to investigate the electrophysiological basis of lymphatic pumping. Approximately 50% of the vessels exhibited spontaneous electrical activity, varying from regular oscillations in membrane potential to spike complexes. Spike complexes generally consisted of one or more action potentials superimposed on a slower depolarization or 'plateau' phase and were often preceded by a slow diastolic depolarization or 'pre-potential'. Norepinephrine (5 M) induced depolarizing events in quiescent preparations. Both agonist-induced oscillations and spike complexes were attenuated or completely abolished by 2-aminoethoxydiphenyl borate (2-APB); 10-100 M). Cesium (1 mM) reduced the frequency of spontaneous firing by approximately 30% by flattening the pre-potential phase. In addition to having a negative inotropic effect, 10 mM Cs ؉ also caused gradual membrane depolarization and prolonged the plateau. 1 M nifedipine abolished spontaneous events while tetrodotoxin (TTX; 0.5-1 M) decreased the amplitude and maximum dV/dt of the spike upstroke or stopped activity completely. Spontaneously active segments of lymphatic vessel were inhibited by the chloride channel blocker, anthracene-9-carboxylic acid (9-AC; 250 M ؊1 mM) suggesting that I Cl(Ca) plays a significant role in the generation of spontaneous activity in this tissue. Penitrem-A (0.1 M) did not affect resting membrane potential but increased action potential amplitude and prolonged the plateau, suggesting that calcium-activated potassium current does not make a significant contribution to resting membrane conductance but is important in membrane repolarization following calcium influx during the action potential. In contrast 4-aminopyridine (4-AP; 5 M) caused significant membrane depolarization, suggesting the existence of an active 4-AP-sensitive current at rest.Conclusions: These results demonstrate that the currents found in isolated voltage-clamped cells from sheep mesenteric lymphatics do play a significant role in the shaping of spontaneous electrical activity of the intact syncitium.

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“…Two types of spikes have been described, longitudinal and circular oriented spikes: each type is characterized by the waveform, by the location on the intestinal tract, and by the pattern of propagation [12]. However, little is known about the relationship between these spikes, the slow waves and the state of the intestines such as during a migrating myoelectric complex (MMC), the fasting state or post-prandially.…”

Section: Introductionmentioning

confidence: 99%

Mapping slow waves and spikes in chronically instrumented conscious dogs: automated on-line electrogram analysis

et al. 2008

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Myoelectric recordings from the gastrointestinal (GI) tract in conscious animals have been limited in duration and site. Recently, we have implanted 24 electrodes and obtained electrograms from these sites simultaneously (200 Hz sampling rate; 1.1 MB/min data stream). An automated electrogram analysis was developed to process this large amount of data. Myoelectrical recordings from the GI tract often consist of slow wave deflections followed by one or more action potentials (=spike deflections) in the same traces. To analyze these signals, a first module separates the signal into one containing only slow waves and a second one containing only spikes. The timings of these waveforms were then detected, in real time, for all 24 electrograms, in a separate slow wave detection module and a separate spike-detection module. Basic statistics such as timing and amplitudes and the number of spikes per slow wave were performed and displayed on-line. In summary, with this online analysis, it is possible to study for long periods of time and under various experimental conditions major components of gastrointestinal motility.

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

Cited by 36 publications

References 27 publications

Patterns of electrical propagation in the intact pregnant guinea pig uterus

Patterns of electrical propagation in the intact pregnant guinea pig uterus

Spontaneous Electrical Activity in Sheep Mesenteric Lymphatics

Mapping slow waves and spikes in chronically instrumented conscious dogs: automated on-line electrogram analysis

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