Interaction of two electrical pacemakers in muscularis of canine proximal colon

Smith, T. K.; Reed, J. B.; Sanders, Kenton M.

doi:10.1152/ajpcell.1987.252.3.c290

Cited by 158 publications

(140 citation statements)

References 16 publications

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“…65 In the stomach ICC-SEP are capable of regenerative propagation of slow waves over distances of at least 20 mm. 63 84 A similar hypothesis including 2 independent pacemakers has also been suggested for pacemaker activity in the rat 85 and mouse 86 colons.…”

Section: -62mentioning

confidence: 53%

The Significance of Interstitial Cells in Neurogastroenterology

Blair¹,

Rhee²,

Sanders³

et al. 2014

J Neurogastroenterol Motil

112

111

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Smooth muscle layers of the gastrointestinal tract consist of a heterogeneous population of cells that include enteric neurons, several classes of interstitial cells of mesenchymal origin, a variety of immune cells and smooth muscle cells (SMCs). Over the last number of years the complexity of the interactions between these cell types has begun to emerge. For example, interstitial cells, consisting of both interstitial cells of Cajal (ICC) and platelet-derived growth factor receptor alpha-positive (PDGFRα + ) cells generate pacemaker activity throughout the gastrointestinal (GI) tract and also transduce enteric motor nerve signals and mechanosensitivity to adjacent SMCs. ICC and PDGFRα + cells are electrically coupled to SMCs possibly via gap junctions forming a multicellular functional syncytium termed the SIP syncytium. Cells that make up the SIP syncytium are highly specialized containing unique receptors, ion channels and intracellular signaling pathways that regulate the excitability of GI muscles. The unique role of these cells in coordinating GI motility is evident by the altered motility patterns in animal models where interstitial cell networks are disrupted. Although considerable advances have been made in recent years on our understanding of the roles of these cells within the SIP syncytium, the full physiological functions of these cells and the consequences of their disruption in GI muscles have not been clearly defined. This review gives a synopsis of the history of interstitial cell discovery and highlights recent advances in structural, molecular expression and functional roles of these cells in the GI tract.

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Section: -62mentioning

confidence: 53%

The Significance of Interstitial Cells in Neurogastroenterology

Blair¹,

Rhee²,

Sanders³

et al. 2014

J Neurogastroenterol Motil

112

111

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show abstract

“…Thus, in the mouse, the plateau potentials generated in the submucosal cells do not couple with the bursts of excitation in the smooth muscle. This is in contrast to the dog proximal colon, where the activity of smooth muscle is produced by the summation of inputs from two discrete populations of pacemakers, the submucosal pacemaker cells and ICC-MY (Smith et al, 1987b;Barajas-Lopez and Huizinga, 1989;Keef et al, 1997).…”

Section: Discussionmentioning

confidence: 88%

“…In the canine colon, however, slow waves recorded in the circular smooth muscle originate from ICC distributed in the submucosal surface of circular muscle layer (submucosal interstitial cells of Cajal, ICC-SM; Smith et al, 1987a). The canine colon also possesses a well developed network of ICC-MY between the circular and longitudinal muscle layers, and the activities generated in these ICC-MY are propagated to both layers of smooth muscle cells to elicit spike potentials through activation of voltage-gated Ca 2+ -channels (Smith et al, 1987b). These may reflect the generation of complicated electrical patterns in the circular smooth muscle of the canine colon (Barajas-Lopez and Huizinga, 1989).…”

Section: Introductionmentioning

confidence: 99%

Effects of Nifedipine and Nickel on Plateau Potentials Generated in Submucosal Interstitial Cells Distributed in the Mouse Proximal Colon.

Yoneda

Takano

Takaki

et al. 2003

J Smooth Muscle Res

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The effects of nifedipine and nickel ions (Ni 2+ ), known inhibitors of L-and T-type voltage-gated Ca-channels respectively, were investigated on plateau potentials recorded from submucosal interstitial cells distributed in the mouse proximal colon. Plateau potentials were generated at a frequency of about 15 times min -1 and were formed of two components. The primary component had an initial fast rate of rise with a transient potential (rate of rise, 130 mV/s; peak amplitude, 35 mV) and was followed by a secondary plateau component with a sustained potential (amplitude, 25 mV; duration, 2.6 s). Each cell from which recordings were made was injected with neurobiotin. Subsequent morphological examination with a confocal microscope indicated successful visualization of injected cells only in the presence of 18β-glycylrhetinic acid (an inhibitor of gap junctional connections), suggesting that these cells were dye-coupled with surrounding cells. The cells injected with neurobiotin exhibited an oval-shaped cell body with bipolar processes and were distributed in the submucosal layer, suggesting that they were submucosal interstitial cells of Cajal (ICC-SM). The plateau potentials were not altered by 0.01 µM nifedipine, but were reduced in duration by 0.1 µM nifedipine, and abolished by 1 µM nifedipine. The rate of rise of plateau potentials, but not their amplitude, was reduced by Ni 2+ (> 10 µM), with no significant alteration of the membrane potential. In the presence of 100 µM Ni 2+ , the plateau potentials were changed to a triangular form. Thus, the plateau potentials were formed by two types of voltage-gated channel current: the initial component was produced by a Ni 2+ -sensitive channel current and the plateau component by a nifedipine-sensitive current. The possible involvement of two different types of voltage-gated Ca 2+ -channels in the generation of submucosal pacemaker potentials was discussed.

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“…As examples, specialized "pacemaker cells" appear to be scattered within smooth muscle tissues of the renal pelvis [6]. A thin layer of specialized smooth muscle cells located in the submucosal layer of the colon is required to generate spontaneous activity in this tissue [7][8][9]. In intestinal smooth muscles, on the other hand, spontaneous activity has been considered to originate in non-muscle cells, the so called "interstitial cells of Cajal" (ICC), distributed at the myenteric layer [10,11].…”

Section: Introductionmentioning

confidence: 99%

Cellular Mechanisms of Myogenic Activity in Gastric Smooth Muscle.

Suzuki

2000

JJP

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Many types of smooth muscle contract spontaneously, with each contraction being accompanied by a slow rhythmic oscillation of the membrane potential (slow wave), a discharge of spike potentials or both [1]. The spontaneous generation of a single spike or bursts of spikes is detected in smooth muscles of the urinary bladder, the uterus (longitudinal muscle layer), the prostate, the isolated longitudinal muscle of the intestine or the portal vein. Slow waves are observed in smooth muscle of the stomach, the circular layer of the intestine and uterus of many species, the renal pelvis, the urethra and the ureter. In several of these muscles, spike potentials are followed. These include the renal pelvis, ureter, uterus (circular muscle), lymphatic vessels and the urethra [2]. As many enteric nerves generate bursts of activity, the transmitters released from these nerves can modulate the activity of smooth muscles [3], and there is a possibility that smooth muscle activity could result indirectly as a consequence of neuronal activity. However, this is rarely the cause of muscle activity since many smooth muscles remain active after neuronal activity has been that ICC may also be the pacemaker cells responsible for gastric activity. However, isolated circular smooth muscle tissues spontaneously generate regenerative potentials, suggesting that there are at least two sites for the initiation of spontaneous activity in the stomach. Regenerative potentials persist in the presence of Ca-antagonists and are inhibited by agents which disrupt intracellular Ca 2ϩ homeostasis. Depolarization of the membrane elicits regenerative potentials after a long delay and the potentials have long refractory periods. This suggests that an unidentified 2nd messenger may be formed during the delay between membrane depolarization and the initiation of a regenerative potential. In gastric muscles of mutant mice which do not express inositol trisphosphate (InsP 3 ) receptors, spike potentials but not slow waves are generated, suggesting the possible involvement of InsP 3 in the initiation of spontaneous activity.

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Interaction of two electrical pacemakers in muscularis of canine proximal colon

Cited by 158 publications

References 16 publications

The Significance of Interstitial Cells in Neurogastroenterology

The Significance of Interstitial Cells in Neurogastroenterology

Effects of Nifedipine and Nickel on Plateau Potentials Generated in Submucosal Interstitial Cells Distributed in the Mouse Proximal Colon.

Cellular Mechanisms of Myogenic Activity in Gastric Smooth Muscle.

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