Electrophysiology of smooth muscle of the small intestine of some mammals.

Hara, Yusuke; Kubota, Midori; Szurszewski, Joseph H.

doi:10.1113/jphysiol.1986.sp016022

Cited by 182 publications

(131 citation statements)

References 29 publications

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“…In the gastrointestinal tract these cells are interstitial cells of Cajal, specialized cells of mesenchymal origin that are required for normal intestinal motility. The main roles for interstitial cells of Cajal are thought to be to generate an electrical signal that paces intestinal smooth muscle (13,20,21,28) and to modulate enteric neurotransmission (29). Our data suggest that an additional role for interstitial cells of Cajal is to generate CO and hyperpolarize intestinal smooth muscle.…”

Section: Discussionmentioning

confidence: 71%

“…There is also a membrane potential gradient across the thickness of circular muscle layer (12,13). In the distal stomach and small intestine the membrane potential in the outer circular smooth muscle region (next to the longitudinal muscle) is Ϸ10 mV hyperpolarized compared with circular smooth muscle cells at the inner circular smooth muscle region (next to the submucosa) (12,13). In the large intestine, the gradient is present but reversed (14).…”

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confidence: 99%

“…In the gastrointestinal tract of all species studied, there is a large gradient (Ϸ30 mV) in membrane potential along the long axis of the stomach from the fundus (proximal stomach) to the pylorus (distal stomach) (12). There is also a membrane potential gradient across the thickness of circular muscle layer (12,13). In the distal stomach and small intestine the membrane potential in the outer circular smooth muscle region (next to the longitudinal muscle) is Ϸ10 mV hyperpolarized compared with circular smooth muscle cells at the inner circular smooth muscle region (next to the submucosa) (12,13).…”

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confidence: 99%

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A major role for carbon monoxide as an endogenous hyperpolarizing factor in the gastrointestinal tract

Farrugia

Sha

Lü

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

106

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Carbon monoxide (CO) is proposed as a physiological messenger. CO activates cGMP and has a direct effect on potassium channels. Both actions of CO lead to hyperpolarization of a cell's resting membrane potential, suggesting that CO may function as a hyperpolarizing factor, although direct evidence is still lacking. Here we take advantage of the known membrane potential gradient that exists in the muscle layers of the gastrointestinal tract to determine whether CO is an endogenous hyperpolarizing factor. We find that heme oxygenase-2-null mice have depolarized smooth muscle cells and that the membrane potential gradient in the gut is abolished. Exogenous CO hyperpolarizes the membrane potential. Regions of the canine gastrointestinal tract that are more hyperpolarized generate more CO and have higher heme oxygenase activity than more depolarized regions. Our results suggest that CO is a critical hyperpolarizing factor required for the maintenance of intestinal smooth muscle membrane potential and gradient.A role for carbon monoxide (CO) is proposed in cell signaling and neurotransmission (1, 2), hormone release (3, 4), as a cytoprotective agent (5), and in regulation of vascular tone (6, 7). The major source of CO is from the breakdown of heme by heme oxygenase (HO); the absence of HO-2, the constitutive HO isoform, significantly impairs the production of CO in gut and other tissues (8). HO-2 is widely expressed in tissues containing smooth muscle, including blood vessels (6), the pulmonary system (9), and the gastrointestinal tract (10), suggesting that CO is continually produced in these tissues. Multiple mechanisms of action for CO have been proposed, including activation of guanylyl cyclase and direct activation of K ϩ channels (11). Both mechanisms can result in membrane hyperpolarization, raising the possibility that CO can act as an endogenous hyperpolarizing factor. To determine whether CO is an endogenous hyperpolarizing factor, we took advantage of the known membrane potential gradients that exist in the muscle layers of the gastrointestinal tract. We chose the gastrointestinal tract as our model because our previous studies in the HO-2-null mouse demonstrate that intestinal smooth muscle is depolarized in the HO-2-null mouse (2), and because of the presence of a measurable smooth muscle membrane potential gradient that has not been reported in vascular smooth muscle. We hypothesized that if CO acts as a physiologically relevant hyperpolarizing factor, then CO production should mirror the membrane potential gradient along the long axis of the stomach as well as across the gut wall and that these resting membrane potential gradients would be diminished or abolished in HO-2-null mice. In the gastrointestinal tract of all species studied, there is a large gradient (Ϸ30 mV) in membrane potential along the long axis of the stomach from the fundus (proximal stomach) to the pylorus (distal stomach) (12). There is also a membrane potential gradient across the thickness of circular muscle layer (12, 13). In the ...

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Section: Discussionmentioning

confidence: 71%

mentioning

confidence: 99%

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confidence: 99%

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A major role for carbon monoxide as an endogenous hyperpolarizing factor in the gastrointestinal tract

Farrugia

Sha

Lü

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

106

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“…2A) 20 , and contractile force. The amplitude of a rhythmic phasic contraction (RPC) in the intact state relates to the number of spikes superimposed on the slow wave, rather than to the amplitude of the slow wave (45,66).…”

Section: Pertinent Background On Topics Essential To Evaluate the Rolmentioning

confidence: 99%

Are interstitial cells of Cajal plurifunction cells in the gut?

Sarna¹

2008

American Journal of Physiology-Gastrointestinal and Liver Physi

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The proposed functions of the interstitial cells of Cajal (ICC) are to 1) pace the slow waves and regulate their propagation, 2) mediate enteric neuronal signals to smooth muscle cells, and 3) act as mechanosensors. In addition, impairments of ICC have been implicated in diverse motility disorders. This review critically examines the available evidence for these roles and offers alternate explanations. This review suggests the following: 1) The ICC may not pace the slow waves or help in their propagation. Instead, they may help in maintaining the gradient of resting membrane potential (RMP) through the thickness of the circular muscle layer, which stabilizes the slow waves and enhances their propagation. The impairment of ICC destabilizes the slow waves, resulting in attenuation of their amplitude and impaired propagation.2) The one-way communication between the enteric neuronal varicosities and the smooth muscle cells occurs by volume transmission, rather than by wired transmission via the ICC. 3) There are fundamental limitations for the ICC to act as mechanosensors.4) The ICC impair in numerous motility disorders. However, a cause-and-effect relationship between ICC impairment and motility dysfunction is not established. The ICC impair readily and transform to other cell types in response to alterations in their microenvironment, which have limited effects on motility function. Concurrent investigations of the alterations in slow-wave characteristics, excitationcontraction and excitation-inhibition couplings in smooth muscle cells, neurotransmitter synthesis and release in enteric neurons, and the impairment of the ICC are required to understand the etiologies of clinical motility disorders. smooth muscle; slow waves; enteric neurons; excitation-contraction coupling; peristaltic reflex; motility disorders; volume transmission; synaptic transmission, ICC THE INTERSTITIAL CELLS WERE characterized originally by Raymond V. Cajal (20,21). These cells got his attention and that of others because they are intercalated between the autonomic nerves and the effector cells. On the basis of the understanding of the interneuronal communication in the central nervous system (CNS) at that time, Cajal proposed that the intercalating cells [later called the interstitial cells of Cajal (ICC)] mediate the transmission of signals from the autonomic neurons to the smooth muscle cells. A few years later, Keith (84) observed a collar of similar cells in the myenteric plexus of the rat ileocecal junction. He was looking for a pacemaker of the gut smooth muscle electrical activity because a few years earlier he had identified such a pacemaker in the sinoatrial node of the heart. He hypothesized that those interstitial cells were the pacemaker cells in the gut. In the late 1960s and early 1970s, several investigators described a plexus of the ICC within the myenteric and submucosal plexi of the small and large intestines. They also identified close connections between the enteric axonal varicosities and ICC processes on one side and g...

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The electrical activity of the bladder after isolation

Kazaryan¹,

Chibukhchyan²,

Mkrtchyan³

2017

PMSE

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Как известно, многие висцеральные органы характеризуются спонтанно генерируемыми электрическими разрядами, которые отмечаются в различных мышечных слоях [1,2]. В верхнем мочевом тракте именно мочеточники, являющиеся парными органами, обеспечивают проведение мочи к мочевому пузырю. Условия для продвижения мочи вдоль мочеточников создаются при возникновении спонтанной контрактуры, сопряженной с пейсмекерной электрической активностью. Пейсмекерный ритмогенез возникает в проксимольной зоне почечной лоханки и впоследствии, координируясь, распространяетcя вдоль мочеточника [2,3].Если к особенностям электрической спонтанной активности данного органа можно отнести строгую ритмичность [4,5], то в мышечных слоях стенок мочевого пузыря регистрируются сопряженные со спайковой пейсмекерной активностью нераспространяющиеся микроконтрактуры. При этом возможно также объединение отдельных потенциалов в группы в виде вспышек активности, которе ассоциируются с

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Electrophysiology of smooth muscle of the small intestine of some mammals.

Cited by 182 publications

References 29 publications

A major role for carbon monoxide as an endogenous hyperpolarizing factor in the gastrointestinal tract

A major role for carbon monoxide as an endogenous hyperpolarizing factor in the gastrointestinal tract

Are interstitial cells of Cajal plurifunction cells in the gut?

The electrical activity of the bladder after isolation

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