The lower esophageal sphincter (LES) is characterized by basal tone and appropriately timed neurogenic relaxation. The physiological mechanisms underlying these crucial LES functions remain poorly understood. The current studies were designed to characterize the electrophysiological properties and neural regulation of LES circular smooth muscle (CSM), and to determine whether interstitial cells of Cajal (ICC) play a role in neurotransmission. Conventional intracellular recordings were performed in CD1, nNOS knock-out, eNOS knock-out and W/Wv mutant mice. Mouse LES consists of “sling” and “clasp” smooth muscle, which were studied separately in CD1 mice. In subsequent studies of mutant mice and respective controls, only the clasp muscle was examined, Immunohistochemical c-Kit staining of ICC was performed in wild-type and W/Wv mutant mice that were first characterized electrophysiologically. The smooth muscle of the LES clasp and sling displayed unitary membrane potentials with a resting membrane potential (RMP) of ~ -43 mV. Spontaneous nifedipine-sensitive action potentials superimposed on the unitary potentials were usually recorded in the LES clasp, but not sling muscle. A monophasic inhibitory junction potential (IJP) was recorded in sling CSM, whereas a biphasic IJP consisting of an initial IJP, followed by long-lasting slow IJP (LSIJP) was recorded in clasp. Further pharmacological studies using control and various knockout mice suggest that: 1. the CSM of the mouse LES is innervated by cholinergic, nitrergic and purinergic nerves; 2. the LSIJP is mediated entirely by nitrergic nerves, whereas purinergic and nitrergic nerves produce the monophasic IJP in the LES sling and initial phase of biphasic IJP in the LES clasp; 3. Ca2+/CaM-kinase II is involved in the regulation of the nitrergic IJPs; 4. TREK-1 K+ channels are not involved in the nitrergic IJP; 5. purinergic and cholinergic neurotransmission is intact in LES CSM of W/Wv mutant mice, whereas nitrergic neurotransmission is impaired in about half of the animals. In animals in which nitrergic neurotransmission was intact, ICC-IM were markedly deficient immunohistologically, suggesting that ICC are not required for nitrergic neurotransmission; 6. impaired nitrergic neurotransmission in W/Wv mutant mice is associated with dysfunction of a Ca2+-dependent signaling cascade primed by spontaneous Ca2+ release from the sarcoplasmic reticulum. / Thesis (Ph.D, Physiology) -- Queen's University, 2008-01-24 15:54:52.175

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24458号 / 理博第4957号 / 新制||理||1708(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 高橋 淑子, 准教授 佐藤 ゆたか, 教授 中務 真人 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

In der kontroversen Diskussion um die unklare Ätiologie der Appendizits wird oft eine Motilitätsstörungen angeführt. Die Interstitial cells of Cajal sind bedeutend für die Motilität und die Entstehung der Peristaltik im menschlichen Kolon. Bei einigen Motilitätsstörungen des Darmes wurde eine Rarifizierung dieser Zellen beobachtet. Die ICC wuden noch nie in der Appendix vermiformis beschrieben.In dieser Arbeit wurden erstmals die ICC in der Appendix mittels einer immunhistochemischen Färbung durch einen maus-monoklonalen Antikörper ( NCL- cKit) nachgewiesen sowie analysiert. Es konnten keine Subgruppen IC-SMP und IC-MP in der Appendix nachgewiesen werden. Die IC-LM zeigten sich reduziert im Vergleich zum Kolon. Die IC-CM konnten zahlreich und regelmäßig dargestellt werden. Eine unterschiedliche Verteilung bzw. Dichte der ICC in der normalen Appendix, der akut und chronisch entzündeten Appendizits konnte nicht nachgewiesen werden.Schlussfolgernd und in Übereinstimmung mit den Beobachtungen anderer Autoren besitzt die Appendix eine reduzierte Motilität und eine physiologische Koprosthase, die aber allein nicht zu einer Entzündung führt. Erst unter dem Einfluss der aus der Literatur bekannten Kofaktoren wird die Koprosthase verstärkt. Erst dies führt zu einer Alteration der Schleimhaut und zur Appendizitis. / The aetiology of the childlike appendicitis is not generally known, but a motility disorder is discussed. The Interstitial cells of Cajal (ICC) are important for the motility and the development of the peristalsis of the colon. In some motility disorders the ICC are abnormaly distributed. The ICC of the human vermiform appendix has never been examined before. We proved and analysed the ICC of the appendix with the mous-monoclonal antibody against c-kit, (NCL-cKit). We could not identify subtypes of ICC, as IC-SMP or IC-MP in the appendix. The IC-LM were reduced compared to the colon. The IC-CM were numerously and regularly distributed. There were no differences in the reduced incidence of ICC between normal vermiform appendix, acute inflamed and chronic inflamed appendicitis.In conclusion and conformance with other observations the appendix has a physiological motility disorder and koprosthasis. Only if some influences of presumably additional cofactors (e.g. inflamation, lymphoid hyperplasia, obstruction), the koprosthasis is intensified, the mucosa is irritated and the appendicitis is developed.

No description available.

No description available.

<p>The small intestine of the gastrointestinal tract displays a variety of motor patterns involved in the mixing, digestion, and propulsion of luminal content. Ultimately, it is the co-ordinated effort of smooth muscle contraction influenced by neural and myogenic stimulation that facilitate these motor patterns. While neural input from the enteric nervous system (ENS) and slow wave producing activity of the peacemaking interstitial cells of Cajal (ICC) in the myenteric plexus (ICC-MP) are key players in the manipulation of smooth muscle cells, the mechanisms behind the onset the segmentation motor pattern are currently unknown. I have demonstrated with intracellular recordings of electrical activity from circular smooth muscle cells, the same nutrient stimulants used to induce the segmentation motor pattern in whole organ preparations evokes the waxing waning phenomenon of the smooth muscle slow wave. Through the use of continuous wavelet transformation analysis on nutrient induced waxing waning, it was determined that the induction of a rhythmic low frequency component is responsible for the generation of waxing waning. Stimulated low frequency activity after methylene blue mediated elimination of ICC-MP slow wave activity suggested the low frequency component did not originate from the ICC-MP. The hypothesis emerged that the ICC of the deep muscular plexus (ICC-DMP), on the opposite side of the circular muscle thickness to the ICC-MP, were responsible for the low frequency oscillations. ICC-DMP networks in close physical proximity to nerve fibers were found to be under tonic inhibited by nitric oxide, and to respond to substance P stimulation. Both alleviation of the inhibition and stimulus by tachykinergic neurotransmission induced the low frequency component and waxing waning. The ENS and myogenic pacemakers play an important role in stimulating the segmentation motor pattern. ICC-DMP are the pacemakers responsible for generation of the low frequency component involved in waxing waning and segmentation.</p> / Master of Science (MSc)

This thesis focuses on elucidating the electrical mechanisms underlying excitation of small intestinal and colonic smooth muscle initiated by interstitial cells of Cajal (ICC). All the ICC subtypes are involved in the orchestration, generation, and/or transmission of electrical signals to smooth muscle to pace gut motor patterns. Some ICC types have intrinsic activity leading to omnipresent rhythmic changes in smooth muscle excitability; others respond to stimuli, inducing pacemaker activity as required. Together they orchestrate motor patterns such as propulsion and segmentation, essential functions of the gut. To study ICC electrophysiology, I utilized patch clamping to record ion channel currents from single intestinal ICC and sharp microelectrodes to record colonic smooth muscle membrane potentials. I have made several discoveries contributing to our understanding of ICC electrophysiology. Firstly, my research increased our understanding of the properties of intrinsic pace-maker activity. I showed that maxi Cl– channels from small intestinal ICC make a significant contribution to slow wave depolarization triggered by intracellular calcium. Secondly, I showed that colonic intramuscular ICC (ICC-IM) selectively express KV7.5 channels, which are suppressed by cholinergic agonists, meaning that excitatory stimuli triggering acetylcholine release deactivate KV7.5 channels, leading to increased excitability. Thirdly, I have shown that the bile acid chenodeoxycholic acid and the nitric oxide donor sodium ni-troprusside both induce pacemaker activity, rhythmic transient depolarisations in mouse colonic muscle, which led to the hypothesis that nitrergic nerves are involved in generating inducible myenteric plexus ICC (ICC-MP) pacemaker activity. It is only when ICC are suitably stimulated by intracellular processes such as rhythmic Ca2+ transients or extracellular signalling from neurotransmitters or small molecules, that ICC produce membrane potential rhythmicity, required for generation of intrinsic slow waves, low-frequency rhythmic transient depolarisations and transmission of excitation into the muscle. / Thesis / Doctor of Philosophy (PhD) / The gut is essential for digestion and absorption of food. The gut has special cells called interstitial cells of Cajal (ICC), which control the contractions of the gut muscle. ICC are pacemaker cells, like those that pace heart beats. To pace gut muscle contractions, ICC generate electrical signals which cause the muscle to contract in an organized rhythmic manner, which promotes mixing or propulsion of gut contents, called motility. I used tiny electrodes to record electrical activity from ICC or gut muscle, to improve our understanding of how ICC pacemaker activity controls motility. My research characterised ion channels, which are microscopic protein pores that allow cells to make electrical currents, that enable generation of pacemaker signals by ICC. I also investigated activation of ICC electrical activity that causes propulsive colonic motility. This will hopefully lead to treatment improvements for patients with motility disorders in the future.

Wang, Hui Chuan. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 184-202). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

This thesis focuses on the characterization of rhythmic activity in the colon of healthy subjects and patients diagnosed with refractory constipation; this activity is mediated by pacemaker cells in the gastrointestinal system, the Interstitial cells of Cajal (ICC). The myogenic activity described are the cyclic motor patterns (CMP) and haustral activity; characterization of these motor patterns in healthy subjects provided control values for the subsequent comparison in patients. Frequency analysis of CMP revealed a novel high-frequency activity (7-15cpm) unrelated to the breathing artefact. Three categories of cyclic motor patterns were observed: (1) CMP following mass peristaltic events (HAPW); (2) those that occur in isolation of other colonic motor patterns (HAPW) in the colon; and (3) low-frequency (2-6cpm), prominently retrograde rhythmic activity in the rectum. CMP were scarcely present in majority of the patients; however, elevated retrograde CMP in the distal colon and rectum in some patients plays a role in retarding flow of colonic content. A detailed characterization of haustral activity (comprised of 2 boundaries and the activity within a haustrum) is reported for the first time using high-resolution colonic manometry. Furthermore, we find that over expression of haustral boundary activity in patients serves as a disproportionate hindrance in colonic transit. An in-depth methodology is developed for the identification and subsequent analysis of haustral activity and CMP; this provides transparency in the data acquisition and analysis. Lastly, a sphincter at the rectosigmoid junction, sphincter of O’Beirne is presented in a patient case report. The persistent presence and paradoxical contractions of this sphincter served to impede flow colonic content, an important factor contributing to the pathophysiology of severe refractory constipation. / Thesis / Master of Science (MSc) / Colonic manometry tests and measures strength and coordination of colonic muscles contractions. This tool was used to understand the rhythmic colonic motor patterns and their contribution to motility in healthy subjects and patients with constipation. Rhythmic activity in the gut is mediated by pacemaker cells, Interstitial cells of Cajal (ICC). We present a detailed characterization of ICC-mediated rhythmic activity that (1) occurs in the small pouches making up the colon (haustra) and (2) is greater than 5cm along the length of the colon (cyclic motor patterns-CMP).CMP possess high-frequency activity (7-15cpm), in addition to activity observed in the low-frequency range (2-6cpm). Activity in the haustra, or haustral activity, is comprised of 2 boundaries with activity within these bounds (intra-haustral activity); the overexpression in patients serves to retard flow of colonic content. Sphincter of O’Beirne is the last haustral boundary at the rectosigmoid junction; its persistent presence was characterized in a patient with refractory constipation.

A fibrilação atrial (FA) é a arritmia cardíaca mais comum na prática clínica e que apresenta a maior morbidade, principalmente com o avançar da idade. O sistema nervoso autonômico, particularmente o balanço adrenérgico/colinérgico, tem profunda influência na ocorrência de fibrilação atrial. A FA pode ser gerada e mantida por uma variedade de mecanismos eletrofisiológicos e uma mudança na atividade autonômica poderá afetar cada um deles de forma diferente. Além do sistema nervoso autônomo, simpático e parassimpático, envolvidos na gênese e manutenção da FA, já é sabido que existem vários outros fatores envolvidos e, dentre eles, as células intersticiais tipo-Cajal (CITC), semelhantes às células intersticiais que contribuem para a atividade motora peristáltica do trato gastrointestinal. Essas células foram encontradas no miocárdio atrial e ventricular, e poderiam ser a origem da atividade deflagradora de focos elétricos ectópicos geradores de FA. O presente estudo teve como objetivos analisar possíveis alterações na expressão miocárdica dos receptores beta-adrenérgicos e quantificar as células intersticiais tipo-Cajal nos átrios de corações humanos, em particular, no esquerdo, e sua relação com a fibrilação atrial permanente (FAP). Para o primeiro objetivo, foram estudados 19 casos de corações de autópsias de portadores de FAP e cardiopatia crônica definida (grupo I), e 19 corações pareados com as mesmas cardiopatias, porém sem evidências de qualquer arritmia supraventricular (grupo II). Foram ressecadas uma amostra no teto do átrio direito, duas no átrio esquerdo, e uma em terminação nervosa envolvida em tecido gorduroso no epicárdio do átrio esquerdo (fat-pad). A expressão miocárdica dos receptores beta-adrenérgicos 1 a 3 e da quinase-5 do receptor adrenérgico acoplado à proteína G (GRK5) foi avaliada pela proporção positiva no miocárdio nos cortes citados. Não houve diferença estatisticamente significante entre os dois grupos quando analisamos a expressão dos receptores adrenérgicos (beta-1, beta-2, beta-3 e GRK5), independentemente do uso ou não de beta-bloqueador. Para o segundo objetivo, foram estudados 6 casos de corações de autópsias de portadores de FAP e cardiopatia crônica definida (grupo I), e 6 corações pareados com as mesmas cardiopatias, porém sem evidências de qualquer arritmia supraventricular (grupo II). As CITC foram avaliadas na região média da parede diafragmática do átrio esquerdo. Não houve alterações estatisticamente significantes entre os grupos estudados, quando avaliamos o número de células positivas no miocárdio pela área do miocárdio em mm2, o número de células positivas no corte inteiro pela área do miocárdio em mm2 ou o número de células positivas no corte inteiro/área do corte inteiro em mm2, seja em relação a cada corte individualmente, ao átrio esquerdo isoladamente e a todos os cortes juntos. Em conclusão, nem alterações na expressão de receptores beta-adrenérgicos nem a presença de células tipo-Cajal parecem ter maior papel na patogênese da fibrilação atrial permanente / Atrial fibrillation (AF) is the most common cardiac arrhythmia in clinical practice, presenting the highest morbidity, especially with advancing age. The autonomic nervous system, particularly the adrenergic/cholinergic balance, has a profound influence on the occurrence of AF. AF can be generated and maintained through a variety of electrophysiological mechanisms, and a change in autonomic activity may affect each of mechanism differently. In addition to the autonomous, sympathetic, and parasympathetic nervous systems involved in the genesis and maintenance of AF, there are several other factors known to be involved, including the interstitial cells of Cajal (ICCs), similar to the interstitial cells that contribute to the peristaltic motor activity of the gastrointestinal tract. These cells were found in the atrial and ventricular myocardium, and could be the source of the triggering activity of ectopic electrical foci that generate AF. In the present study, we aimed to analyze the possible changes in the myocardial expression of beta-adrenergic receptors and to quantify ICCs in the atria of human hearts, in particular in the left atrium, and its relation with permanent AF (PAF). For the first objective, we studied 19 hearts from autopsies of patients with PAF and defined chronic cardiomyopathy (group I), and 19 paired hearts with the same cardiomyopathy but without evidence of any supraventricular arrhythmia (group II). A tissue sample from the ceiling of the right atrium, two from the left atrium, and one from the nerve ending involved in the adipose tissue in the epicardium of the left atrium (fat pad) were resected. The myocardial expression of beta-adrenergic receptors 1 and 3, and of the G protein-coupled receptor kinase 5 (GRK5) was assessed according to the positive proportion in the myocardium in the mentioned sections. There was no statistically significant difference between the two groups in the expression of adrenergic receptors (beta-1, beta-2, beta-3, and GRK5), regardless of the use or nonuse of beta-blockers. For the second objective, six hearts from autopsied patients with PAF and defined chronic cardiopathy (group I) were studied, along with six paired hearts with the same cardiopathies but without evidence of any supraventricular arrhythmia (group II). The ICCs were evaluated in the middle region of the diaphragmatic wall of the left atrium. There were no statistically significant changes between the groups when we evaluated the number of positive cells in the myocardium by area of the myocardium in mm2, the number of positive cells in the full section by area of the myocardium in mm2, or the number of positive cells in the full section/area of the full section in mm2, be it in relation to each section individually, the left atrium alone, or all sections together. In conclusion, neither changes in the expression of beta-adrenergic receptors nor the presence of ICCs seem to have a large role in the pathogenesis of permanent AF