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Biagioni C, Traini C, Faussone‐Pellegrini MS, Idrizaj E, Baccari MC, Vannucchi MG. Prebiotics counteract the morphological and functional changes secondary to chronic cisplatin exposition in the proximal colon of mice. J Cell Mol Med 2024; 28:e18161. [PMID: 38445787 PMCID: PMC10915824 DOI: 10.1111/jcmm.18161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 01/05/2024] [Accepted: 01/18/2024] [Indexed: 03/07/2024] Open
Abstract
Cisplatin is an antimitotic drug able to cause acute and chronic gastrointestinal side effects. Acute side effects are attributable to mucositis while chronic ones are due to neuropathy. Cisplatin has also antibiotic properties inducing dysbiosis which enhances the inflammatory response, worsening local damage. Thus, a treatment aimed at protecting the microbiota could prevent or reduce the toxicity of chemotherapy. Furthermore, since a healthy microbiota enhances the effects of some chemotherapeutic drugs, prebiotics could also improve this drug effectiveness. We investigated whether chronic cisplatin administration determined morphological and functional alterations in mouse proximal colon and whether a diet enriched in prebiotics had protective effects. The results showed that cisplatin caused lack of weight gain, increase in kaolin intake, decrease in stool production and mucus secretion. Prebiotics prevented increases in kaolin intake, changes in stool production and mucus secretion, but had no effect on the lack of weight gain. Moreover, cisplatin determined a reduction in amplitude of spontaneous muscular contractions and of Connexin (Cx)43 expression in the interstitial cells of Cajal, changes that were partially prevented by prebiotics. In conclusion, the present study shows that daily administration of prebiotics, likely protecting the microbiota, prevents most of the colonic cisplatin-induced alterations.
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Affiliation(s)
- Cristina Biagioni
- Research Unit of Histology and Embryology, Department of Experimental and Clinical MedicineUniversity of FlorenceFlorenceItaly
| | - Chiara Traini
- Research Unit of Histology and Embryology, Department of Experimental and Clinical MedicineUniversity of FlorenceFlorenceItaly
| | | | - Eglantina Idrizaj
- Section of Physiological Sciences, Department of Experimental and Clinical MedicineUniversity of FlorenceFlorenceItaly
| | - Maria Caterina Baccari
- Section of Physiological Sciences, Department of Experimental and Clinical MedicineUniversity of FlorenceFlorenceItaly
| | - Maria Giuliana Vannucchi
- Research Unit of Histology and Embryology, Department of Experimental and Clinical MedicineUniversity of FlorenceFlorenceItaly
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2
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Prowse KL, Law H, Raez-Villanueva S, Markovic F, Wang M, Borojevic R, Parsons SP, Vincent AD, Holloway AC, Ratcliffe EM. Effects of in utero exposure to fluoxetine on the gastrointestinal tract of rat offspring. Am J Physiol Gastrointest Liver Physiol 2023; 325:G528-G538. [PMID: 37724979 DOI: 10.1152/ajpgi.00223.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 09/13/2023] [Accepted: 09/13/2023] [Indexed: 09/21/2023]
Abstract
Perinatal exposure to selective serotonin reuptake inhibitors (SSRIs) has been shown to disrupt the development of serotonergic signaling pathways in the brain and enteric nervous system. Serotonin (5-hydroxytryptamine; 5-HT) signaling is critical for gastrointestinal homeostasis; changes in 5-HT expression and regulation have been associated with gastrointestinal diseases of motility and inflammation. We tested the hypothesis that perinatal exposure to the SSRI fluoxetine can influence the development of the gastrointestinal tract in exposed offspring. Female nulliparous Wistar rats were given fluoxetine (10 mg/kg) or vehicle control from 2 wk before mating until weaning; small and large intestines of female and male offspring were collected at postnatal days 1, 21 (P1, P21, respectively), and 6 mo of age. In histological preparations, the proportion of serotonergic neurons significantly increased in the colons of both female and male fluoxetine-exposed compared with control offspring at P21, a time point that signifies maximal exposure to fluoxetine. At 6 mo of age, male but not female fluoxetine-exposed offspring had a significant increase in circulating 5-HT, with a significant decrease in transcripts encoding the 5-HT2A receptor and monoamine oxidase as compared with control offspring. Measurement of spatiotemporal mapping of contractile activity of the small and large intestine at 6 mo of age revealed no changes in motility in the small bowel of fluoxetine-exposed offspring but revealed a significant increase in the frequency of colonic contractions in the female fluoxetine-exposed compared with control animals. Susceptibility to inflammation was examined at 6 mo using the dextran sulfate sodium model of acute colitis. In utero exposure to fluoxetine was not found to exacerbate colitis severity. These findings suggest that fluoxetine exposure during fetal and early postnatal development can lead to changes in serotonergic neurons at the peak of exposure with sex-specific changes in 5-HT signaling and colonic motility in adulthood.NEW & NOTEWORTHY There is increasing recognition of the relevance of in utero and early postnatal exposures in the developmental programming of the gastrointestinal tract. Perinatal exposure to selective serotonin reuptake inhibitors and antidepressant medications is of particular relevance as they are commonly prescribed during pregnancy, and serotonergic pathways play key roles during gastrointestinal development and in postnatal homeostasis. Here, we provide a comprehensive evaluation of clinically relevant outcomes of gastrointestinal motility and susceptibility to colitis in fluoxetine-exposed offspring and highlight changes in colonic serotonergic neurons at the peak of perinatal fluoxetine exposure with sex-dependent changes in serotonin signaling and colonic motility in adulthood.
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Affiliation(s)
- Katherine L Prowse
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Harriet Law
- Department of Obstetrics and Gynecology, McMaster University, Hamilton, Ontario, Canada
| | | | - Filip Markovic
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Megan Wang
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Rajka Borojevic
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Sean P Parsons
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Alexander D Vincent
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Alison C Holloway
- Department of Obstetrics and Gynecology, McMaster University, Hamilton, Ontario, Canada
| | - Elyanne M Ratcliffe
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
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3
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Ryzhii M, Ryzhii E. Pacemaking function of two simplified cell models. PLoS One 2022; 17:e0257935. [PMID: 35404982 PMCID: PMC9000119 DOI: 10.1371/journal.pone.0257935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 03/29/2022] [Indexed: 12/03/2022] Open
Abstract
Simplified nonlinear models of biological cells are widely used in computational electrophysiology. The models reproduce qualitatively many of the characteristics of various organs, such as the heart, brain, and intestine. In contrast to complex cellular ion-channel models, the simplified models usually contain a small number of variables and parameters, which facilitates nonlinear analysis and reduces computational load. In this paper, we consider pacemaking variants of the Aliev-Panfilov and Corrado two-variable excitable cell models. We conducted a numerical simulation study of these models and investigated the main nonlinear dynamic features of both isolated cells and 1D coupled pacemaker-excitable systems. Simulations of the 2D sinoatrial node and 3D intestine tissue as application examples of combined pacemaker-excitable systems demonstrated results similar to obtained previously. The uniform formulation for the conventional excitable cell models and proposed pacemaker models allows a convenient and easy implementation for the construction of personalized physiological models, inverse tissue modeling, and development of real-time simulation systems for various organs that contain both pacemaker and excitable cells.
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Affiliation(s)
- Maxim Ryzhii
- Complex Systems Modeling Laboratory, University of Aizu, Aizu-Wakamatsu, Japan
- * E-mail:
| | - Elena Ryzhii
- Department of Anatomy and Histology, Fukushima Medical University, Fukushima, Japan
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4
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O'Grady G, Gharibans AA, Du P, Huizinga JD. The gastric conduction system in health and disease: a translational review. Am J Physiol Gastrointest Liver Physiol 2021; 321:G527-G542. [PMID: 34549598 DOI: 10.1152/ajpgi.00065.2021] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Gastric peristalsis is critically dependent on an underlying electrical conduction system. Recent years have witnessed substantial progress in clarifying the operations of this system, including its pacemaking units, its cellular architecture, and slow-wave propagation patterns. Advanced techniques have been developed for assessing its functions at high spatiotemporal resolutions. This review synthesizes and evaluates this progress, with a focus on human and translational physiology. A current conception of the initiation and conduction of slow-wave activity in the human stomach is provided first, followed by a detailed discussion of its organization at the cellular and tissue level. Particular emphasis is then given to how gastric electrical disorders may contribute to disease states. Gastric dysfunction continues to grow in their prevalence and impact, and while gastric dysrhythmia is established as a clear and pervasive feature in several major gastric disorders, its role in explaining pathophysiology and informing therapy is still emerging. New insights from high-resolution gastric mapping are evaluated, together with historical data from electrogastrography, and the physiological relevance of emerging biomarkers from body surface mapping such as retrograde propagating slow waves. Knowledge gaps requiring further physiological research are highlighted.
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Affiliation(s)
- Gregory O'Grady
- Department of Surgery, The University of Auckland, Auckland, New Zealand.,Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Armen A Gharibans
- Department of Surgery, The University of Auckland, Auckland, New Zealand.,Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Peng Du
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Jan D Huizinga
- Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
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5
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Appukuttan S, Brain KL, Manchanda R. Effect of Variations in Gap Junctional Coupling on the Frequency of Oscillatory Action Potentials in a Smooth Muscle Syncytium. Front Physiol 2021; 12:655225. [PMID: 34658901 PMCID: PMC8517141 DOI: 10.3389/fphys.2021.655225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 09/02/2021] [Indexed: 11/13/2022] Open
Abstract
Gap junctions provide pathways for intercellular communication between adjacent cells, allowing exchange of ions and small molecules. Based on the constituent protein subunits, gap junctions are classified into different subtypes varying in their properties such as unitary conductances, sensitivity to transjunctional voltage, and gating kinetics. Gap junctions couple cells electrically, and therefore the electrical activity originating in one cell can affect and modulate the electrical activity in adjacent cells. Action potentials can propagate through networks of such electrically coupled cells, and this spread is influenced by the nature of gap junctional coupling. Our study aims to computationally explore the effect of differences in gap junctional properties on oscillating action potentials in electrically coupled tissues. Further, we also explore variations in the biophysical environment by altering the size of the syncytium, the location of the pacemaking cell, as well as the occurrence of multiple pacemaking cells within the same syncytium. Our simulation results suggest that the frequency of oscillations is governed by the extent of coupling between cells and the gating kinetics of different gap junction subtypes. The location of pacemaking cells is found to alter the syncytial behavior, and when multiple oscillators are present, there exists an interplay between the oscillator frequency and their relative location within the syncytium. Such variations in the frequency of oscillations can have important implications for the physiological functioning of syncytial tissues.
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Affiliation(s)
- Shailesh Appukuttan
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Keith L. Brain
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Rohit Manchanda
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
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6
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Huizinga JD, Pervez M, Nirmalathasan S, Chen JH. Characterization of haustral activity in the human colon. Am J Physiol Gastrointest Liver Physiol 2021; 320:G1067-G1080. [PMID: 33909507 DOI: 10.1152/ajpgi.00063.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Contraction patterns of the human colon are rarely discussed from the perspective of its haustra. Colonic motility was analyzed in 21 healthy subjects using 84-sensor manometry catheters with 1-cm sensor spacing. Capsule endoscopy and manometry showed evidence of narrow rhythmic circular muscle contractions. X-ray images of haustra and sensor locations allowed us to identify manometry motor activity as intrahaustral activity. Two common motor patterns were observed that we infer to be associated with individual haustra: rhythmic pressure activity confined to a single sensor, and activity confined to a section of the colon of 3-6 cm length. Intrahaustral activity was observed by 3-4 sensors. Approximately 50% of the haustra were intermittently active for ∼30% of the time; 2,402 periods of haustral activity were analyzed. Intrahaustral activity showed rhythmic pressure waves, propagating in mixed direction, 5-30 mmHg in amplitude at a frequency of ∼3 cpm (range 2-6) or ∼12 cpm (range 7-15), or exhibiting a checkerboard segmentation pattern. Boundaries of the haustra showed rhythmic pressure activity with or without elevated baseline pressure. Active haustra often showed no boundary activity probably allowing transit to neighboring haustra. Haustral boundaries were seen at the same sensor for the 6- to 8-h study duration, indicating that they did not propagate, thereby likely contributing to continence. The present study elucidates the motility characteristics of haustral boundaries and the nature of intrahaustral motor patterns and paves the way for investigating their possible role in pathophysiology of defecation disorders.NEW & NOTEWORTHY Here, we present the first full characterization and quantification of motor patterns that we infer to be confined to single haustra, both intrahaustral activity and haustral boundary activity, in the human colon using high-resolution manometry. Haustral activity is intermittent but consistently present in about half of the haustra. Intrahaustral activity presents as a cyclic motor pattern of mixed propagation direction dominated by simultaneous pressure waves that can resolve into checkerboard segmentation, allowing for mixing, absorption, and stool formation.
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Affiliation(s)
- Jan D Huizinga
- Division of Gastroenterology, Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Maham Pervez
- Division of Gastroenterology, Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Sharjana Nirmalathasan
- Division of Gastroenterology, Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Ji-Hong Chen
- Division of Gastroenterology, Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
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7
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Parsons SP, Huizinga JD. Nitric Oxide Is Essential for Generating the Minute Rhythm Contraction Pattern in the Small Intestine, Likely via ICC-DMP. Front Neurosci 2021; 14:592664. [PMID: 33488345 PMCID: PMC7817771 DOI: 10.3389/fnins.2020.592664] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 11/25/2020] [Indexed: 12/16/2022] Open
Abstract
Nitrergic nerves have been proposed to play a critical role in the orchestration of peristaltic activities throughout the gastrointestinal tract. In the present study, we investigated the role of nitric oxide, using spatiotemporal mapping, in peristaltic activity of the whole ex vivo mouse intestine. We identified a propulsive motor pattern in the form of propagating myogenic contractions, that are clustered by the enteric nervous system into a minute rhythm that is dependent on nitric oxide. The cluster formation was abolished by TTX, lidocaine and nitric oxide synthesis inhibition, whereas the myogenic contractions, occurring at the ICC-MP initiated slow wave frequency, remained undisturbed. Cluster formation, inhibited by block of nitric oxide synthesis, was fully restored in a highly regular rhythmic fashion by a constant level of nitric oxide generated by sodium nitroprusside; but the action of sodium nitroprusside was inhibited by lidocaine indicating that it was relying on neural activity, but not rhythmic nitrergic nerve activity. Hence, distention-induced activity of cholinergic nerves and/or a co-factor within nitrergic nerves such as ATP is also a requirement for the minute rhythm. Cluster formation was dependent on distention but was not evoked by a distention reflex. Block of gap junction conductance by carbenoxolone, dose dependently inhibited, and eventually abolished clusters and contraction waves, likely associated, not with inhibition of nitrergic innervation, but by abolishing ICC network synchronization. An intriguing feature of the clusters was the presence of bands of rhythmic inhibitions at 4-8 cycles/min; these inhibitory patches occurred in the presence of tetrodotoxin or lidocaine and hence were not dependent on nitrergic nerves. We propose that the minute rhythm is generated by nitric oxide-induced rhythmic depolarization of the musculature via ICC-DMP.
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Affiliation(s)
- Sean P. Parsons
- Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| | - Jan D. Huizinga
- Department of Medicine and School of Biomedical Engineering, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
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8
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Modulation of contractions in the small intestine indicate desynchronization via supercritical Andronov-Hopf bifurcation. Sci Rep 2020; 10:15099. [PMID: 32934308 PMCID: PMC7494877 DOI: 10.1038/s41598-020-71999-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 08/21/2020] [Indexed: 11/08/2022] Open
Abstract
The small intestine is covered by a network of coupled oscillators, the interstitial cells of Cajal (ICC). These oscillators synchronize to generate rhythmic phase waves of contraction. At points of low coupling, oscillations desynchronise, frequency steps occur and every few waves terminates as a dislocation. The amplitude of contractions is modulated at frequency steps. The phase difference between contractions at a frequency step and a proximal reference point increased slowly at first and then, just at the dislocation, increased rapidly. Simultaneous frequency and amplitude modulation (AM/FM) results in a Fourier frequency spectrum with a lower sideband, a so called Lashinsky spectrum, and this was also seen in the small intestine. A model of the small intestine consisting of a chain of coupled Van der Pol oscillators, also demonstrated simultaneous AM/FM at frequency steps along with a Lashinsky spectrum. Simultaneous AM/FM, together with a Lashinsky spectrum, are predicted to occur when periodically-forced or mutually-coupled oscillators desynchronise via a supercritical Andronov-Hopf bifurcation and have been observed before in other physical systems of forced or coupled oscillators in plasma physics and electrical engineering. Thus motility patterns in the intestine can be understood from the viewpoint of very general dynamical principles.
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9
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Tan W, Lee G, Chen JH, Huizinga JD. Relationships Between Distention-, Butyrate- and Pellet-Induced Stimulation of Peristalsis in the Mouse Colon. Front Physiol 2020; 11:109. [PMID: 32132933 PMCID: PMC7040375 DOI: 10.3389/fphys.2020.00109] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 01/30/2020] [Indexed: 12/12/2022] Open
Abstract
Background/Aims Luminal factors such as short-chain fatty acids are increasingly recognized for playing a regulatory role in peristaltic activity. Our objective was to understand the roles of butyrate and propionate in regulating peristaltic activity in relation to distention-induced activities. Methods Butyrate and propionate were perfused intraluminally under varying intraluminal pressures in murine colons bathed in Krebs solution. We used video recording and spatiotemporal maps to examine peristalsis induced by the intrinsic rhythmic colonic motor complex (CMC) as well as pellet-induced peristaltic reflex movements. Results The CMC showed several configurations at different levels of excitation, culminating in long distance contractions (LDCs) which possess a triangular shape in murine colon spatiotemporal maps. Butyrate increased the frequency of CMCs but was a much weaker stimulus than distention and only contributed to significant changes under low distention. Propionate inhibited CMCs by decreasing either their amplitudes or frequencies, but only in low distention conditions. Butyrate did not consistently counteract propionate-induced inhibition likely due to the multiple and distinct mechanisms of action for these signaling molecules in the lumen. Pellet movement occurred through ongoing CMCs as well as pellet induced peristaltic reflex movements and butyrate augmented both types of peristaltic motor patterns to decrease the amount of time required to expel each pellet. Conclusions Butyrate is effective in promoting peristalsis, but only when the level of colonic activity is low such as under conditions of low intraluminal pressure. This suggests that it may play a significant role in patients with poor fiber intake, where there is low mechanical stimulation in the lumen.
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Affiliation(s)
- Wei Tan
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, China.,Department of Medicine, Division of Gastroenterology, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| | - Grace Lee
- Department of Medicine, Division of Gastroenterology, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| | - Ji-Hong Chen
- Department of Medicine, Division of Gastroenterology, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| | - Jan D Huizinga
- Department of Medicine, Division of Gastroenterology, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
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10
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Parsons SP, Huizinga JD. A myogenic motor pattern in mice lacking myenteric interstitial cells of Cajal explained by a second coupled oscillator network. Am J Physiol Gastrointest Liver Physiol 2020; 318:G225-G243. [PMID: 31813235 PMCID: PMC7052571 DOI: 10.1152/ajpgi.00311.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The interstitial cells of Cajal associated with the myenteric plexus (ICC-MP) are a network of coupled oscillators in the small intestine that generate rhythmic electrical phase waves leading to corresponding waves of contraction, yet rhythmic action potentials and intercellular calcium waves have been recorded from c-kit-mutant mice that lack the ICC-MP, suggesting that there may be a second pacemaker network. The gap junction blocker carbenoxolone induced a "pinstripe" motor pattern consisting of rhythmic "stripes" of contraction that appeared simultaneously across the intestine with a period of ~4 s. The infinite velocity of these stripes suggested they were generated by a coupled oscillator network, which we call X. In c-kit mutants rhythmic contraction waves with the period of X traveled the length of the intestine, before the induction of the pinstripe pattern by carbenoxolone. Thus X is not the ICC-MP and appears to operate under physiological conditions, a fact that could explain the viability of these mice. Individual stripes consisted of a complex pattern of bands of contraction and distension, and between stripes there could be slide waves and v waves of contraction. We hypothesized that these phenomena result from an interaction between X and the circular muscle that acts as a damped oscillator. A mathematical model of two chains of coupled Fitzhugh-Nagumo systems, representing X and circular muscle, supported this hypothesis. The presence of a second coupled oscillator network in the small intestine underlines the complexity of motor pattern generation in the gut.NEW & NOTEWORTHY Physiological experiments and a mathematical model indicate a coupled oscillator network in the small intestine in addition to the c-kit-expressing myenteric interstitial cells of Cajal. This network interacts with the circular muscle, which itself acts as a system of damped oscillators, to generate physiological contraction waves in c-kit (W) mutant mice.
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Affiliation(s)
- Sean P. Parsons
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Jan D. Huizinga
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
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11
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Shokrollahi M, Chen JH, Huizinga JD. Intraluminal prucalopride increases propulsive motor activities via luminal 5-HT 4 receptors in the rabbit colon. Neurogastroenterol Motil 2019; 31:e13598. [PMID: 31012538 DOI: 10.1111/nmo.13598] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 03/13/2019] [Accepted: 03/28/2019] [Indexed: 02/08/2023]
Abstract
BACKGROUND Activating luminal 5-HT4 receptors results in the release of 5-HT from enterochromaffin cells into the lamina propria to modulate colonic motility. Our aim was to evaluate characteristics of colonic motor patterns involved in the prokinetic effects of intraluminal prucalopride in the rabbit colon. METHODS Colonic motor patterns were studied ex vivo using simultaneous spatiotemporal diameter mapping and pressure sensing. KEY RESULTS Intraluminal prucalopride and intraluminal exogenous 5-HT strongly evoked or enhanced the colonic motor complex at all levels of excitation beginning with generation of clusters of fast propagating contractions (FPCs), then development of long-distance contractions (LDCs) within the clusters, and finally forceful LDCs as the highest level of excitation. Intraluminal prucalopride and intraluminal exogenous 5-HT stimulated propulsive motor activity in a dose-dependent and antagonist-sensitive manner by increasing the contraction amplitude, intraluminal pressure, frequency, velocity, and degree of propagation of the colonic motor complex. CONCLUSIONS AND INFERENCES Activating mucosal 5-HT4 receptors via intraluminal prucalopride or 5-HT increases propulsive motor activity in a graded manner; that is, depending on starting conditions, amplitudes or frequencies of an activity may increase or a new pattern may be initiated. Our data support further studies into delivering 5-HT4 receptor agonists via colon-targeted drug delivery systems and studies into the role of luminal 5-HT as an essential requirement for normal colon motor pattern generation.
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Affiliation(s)
- Mitra Shokrollahi
- Division of Gastroenterology, Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Ji-Hong Chen
- Division of Gastroenterology, Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Jan D Huizinga
- Division of Gastroenterology, Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
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12
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Corsetti M, Costa M, Bassotti G, Bharucha AE, Borrelli O, Dinning P, Di Lorenzo C, Huizinga JD, Jimenez M, Rao S, Spiller R, Spencer NJ, Lentle R, Pannemans J, Thys A, Benninga M, Tack J. First translational consensus on terminology and definitions of colonic motility in animals and humans studied by manometric and other techniques. Nat Rev Gastroenterol Hepatol 2019; 16:559-579. [PMID: 31296967 PMCID: PMC7136172 DOI: 10.1038/s41575-019-0167-1] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/30/2019] [Indexed: 12/19/2022]
Abstract
Alterations in colonic motility are implicated in the pathophysiology of bowel disorders, but high-resolution manometry of human colonic motor function has revealed that our knowledge of normal motor patterns is limited. Furthermore, various terminologies and definitions have been used to describe colonic motor patterns in children, adults and animals. An example is the distinction between the high-amplitude propagating contractions in humans and giant contractions in animals. Harmonized terminology and definitions are required that are applicable to the study of colonic motility performed by basic scientists and clinicians, as well as adult and paediatric gastroenterologists. As clinical studies increasingly require adequate animal models to develop and test new therapies, there is a need for rational use of terminology to describe those motor patterns that are equivalent between animals and humans. This Consensus Statement provides the first harmonized interpretation of commonly used terminology to describe colonic motor function and delineates possible similarities between motor patterns observed in animal models and humans in vitro (ex vivo) and in vivo. The consolidated terminology can be an impetus for new research that will considerably improve our understanding of colonic motor function and will facilitate the development and testing of new therapies for colonic motility disorders.
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Affiliation(s)
- Maura Corsetti
- NIHR Nottingham Biomedical Research Centre (BRC), Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK
- Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK
| | - Marcello Costa
- Human Physiology and Centre of Neuroscience, College of Medicine, Flinders University, Bedford Park, South Australia, Australia
| | - Gabrio Bassotti
- Department of Medicine, University of Perugia Medical School, Perugia, Italy
| | - Adil E Bharucha
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA
| | - Osvaldo Borrelli
- Department of Paediatric Gastroenterology, Great Ormond Street Hospital for Sick Children, London, UK
| | - Phil Dinning
- Human Physiology and Centre of Neuroscience, College of Medicine, Flinders University, Bedford Park, South Australia, Australia
- Department of Gastroenterology and Surgery, Flinders Medical Centre, Adelaide, South Australia, Australia
| | - Carlo Di Lorenzo
- Department of Pediatric Gastroenterology, Nationwide Children's Hospital, The Ohio State University, Columbus, OH, USA
| | - Jan D Huizinga
- Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Marcel Jimenez
- Department of Cell Physiology, Physiology and Immunology and Neuroscience Institute, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Satish Rao
- Division of Gastroenterology/Hepatology, Augusta University, Augusta, GA, USA
| | - Robin Spiller
- NIHR Nottingham Biomedical Research Centre (BRC), Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK
- Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK
| | - Nick J Spencer
- Discipline of Human Physiology, School of Medicine, Flinders University, Bedford Park, South Australia, Australia
| | - Roger Lentle
- Digestive Biomechanics Group, College of Health, Massey University, Palmerston North, New Zealand
| | - Jasper Pannemans
- Department of Paediatric Gastroenterology and Nutrition, Emma Children's Hospital/Academic Medical Centre, Amsterdam, Netherlands
| | - Alexander Thys
- Department of Paediatric Gastroenterology and Nutrition, Emma Children's Hospital/Academic Medical Centre, Amsterdam, Netherlands
| | - Marc Benninga
- Translational Research Center for Gastrointestinal disorders (TARGID), Department of Clinical and Experimental Medicine, University of Leuven, Leuven, Belgium
| | - Jan Tack
- Department of Paediatric Gastroenterology and Nutrition, Emma Children's Hospital/Academic Medical Centre, Amsterdam, Netherlands.
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Hanman A, Chen JH, Parsons SP, Huizinga JD. Noradrenaline inhibits neurogenic propulsive motor patterns but not neurogenic segmenting haustral progression in the rabbit colon. Neurogastroenterol Motil 2019; 31:e13567. [PMID: 30761706 DOI: 10.1111/nmo.13567] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 01/12/2019] [Accepted: 01/13/2019] [Indexed: 02/08/2023]
Abstract
BACKGROUND Excessive sympathetic inhibition may be a cause of colon motor dysfunction. Our aim was to better understand the mechanisms of sympathetic inhibition on colonic motor patterns using the rabbit colon, hypothesizing that noradrenaline selectively inhibits propulsive motor patterns. METHODS Changes in motor patterns of the rabbit colon were studied ex vivo using noradrenaline and adrenoceptor antagonists and analyzed using spatiotemporal diameter maps. KEY RESULTS Noradrenaline abolished propulsive contractions: it abolished the long-distance contractions (LDCs) from a baseline frequency of 0.8 ± 0.3 and the clusters of fast propagating contractions (FPCs) at a frequency of 14.4 ± 2.8 cpm. Both motor patterns recovered after addition of the α2 -adrenoceptor antagonist yohimbine to a frequency of 0.5 ± 0.2 and 9.9 ± 3.3 cpm, respectively. The β-adrenoceptor antagonist propranolol did not prevent the loss of propulsive motor patterns with noradrenaline. Noradrenaline did not inhibit haustral boundary contractions and increased the frequency of the myogenic ripples from 8.3 ± 1.4 to 10.5 ± 1.3 cpm which was not affected by yohimbine, propranolol nor the α1 -adrenoceptor blocker prazosin. CONCLUSIONS AND INFERENCES Noradrenergic inhibition of propulsive motor patterns is mediated by the α2 -adrenoceptor to inhibit the neurogenic LDCs and the neurogenic clustering of FPCs. The neurogenic haustral boundary contractions are not affected, suggesting that α2- receptors are on selective neural circuits. The excitatory effect of noradrenaline on ripples may be due to the activation of adrenoceptors on interstitial cells of Cajal, but action on α1- receptors was excluded. No role for the β-adrenoceptor was found.
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Affiliation(s)
- Alicia Hanman
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Ji-Hong Chen
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Sean P Parsons
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Jan D Huizinga
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
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14
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Hulls CM, Lentle RG, King QM, Chambers JP, Reynolds GW. Pharmacological modulation of the spatiotemporal disposition of micromotions in the intact resting urinary bladder of the rabbit; their pattern is under both myogenic and autonomic control. BJU Int 2019; 123 Suppl 5:54-64. [PMID: 31017744 DOI: 10.1111/bju.14715] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVES To explore and characterize the disposition and dynamics of micromotions in the wall of the intact resting teradotoxinized urinary bladder of the rabbit before and after the administration of adrenergic and cholinergic pharmaceutical agents. METHODS Spatiotemporal maps and related intravesical pressure were used to analyse propagating patches of contractions (PPCs) and their component individual myogenic contractions [propagating individual contractions (PICs)] in the wall of the tetradotoxinized urinary bladder. RESULTS The bladder wall exhibited two contractile states that were of similar frequencies to those of the two types of electrophysiological discharge described in previous studies; the first, in which cyclic PPCs predominated, the second in which small irregular PICs predominated. The addition of carbachol increased the size, frequency, speed and distance of propagation of PPCs, whereas the addition of isoprenaline temporarily halted the incorporation of PICs into PPCs, and reduced patch size and total area undergoing contraction. The RhoA kinase (ROCK) inhibitor Y-27632 reduced both largest patch index and mean patch size. Both carbenoxolone and ROCK inhibition decreased the duration of PPCs. Carbenoxolone also prolonged duration and accelerated PPC propagation velocity. The authors postulate that these differences arise from differing effects of these agents on myocytes and interstitial cells within the stress environment of the bladder, influencing the development, coordination and propagation of PPCs. CONCLUSIONS The timings and structure of spontaneous micromotions in the wall of the isolated bladder change when it is treated with sympathetic/parasympathetic agonists and with myogenically active agents. Correspondingly, disorders of bladder wall contraction may result from disorders of either neurogenic or myogenic signalling and may be amenable to treatment with combinations of agents that influence both.
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Affiliation(s)
- Corrin Murray Hulls
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
| | - Roger Graham Lentle
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
| | | | - John Paul Chambers
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
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15
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Wong J, Chopra J, Chiang LLW, Liu T, Ho J, Wu WKK, Tse G, Wong SH. The Role of Connexins in Gastrointestinal Diseases. J Mol Biol 2019; 431:643-652. [PMID: 30639409 DOI: 10.1016/j.jmb.2019.01.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 10/03/2018] [Accepted: 01/04/2019] [Indexed: 12/13/2022]
Abstract
Gap junctions are hexagonal arrays of protein molecules in the plasma membrane and were first described in Mauthner cell synapses of goldfish. They form pathways for coupling between cells, allowing passive, electrotonic spread of ions and also passage of larger molecules such as amino acids and nucleotides. They are expressed in both excitable and non-excitable tissues. Each gap junction is made of two connexons, which are hexameric proteins of the connexin subunit. In this review, the roles that connexins play in gastrointestinal motility, the mechanisms of altered connexin expression leading to inflammatory bowel disease, gastrointestinal infections, and gastrointestinal symptoms in autistic spectrum disorder are discussed in detail.
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Affiliation(s)
- Jeremy Wong
- Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, PR China
| | - Jasmine Chopra
- Faculty of Arts and Science, University of Toronto, Toronto, Canada
| | | | - Tong Liu
- Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular disease, Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin 300211, PR China
| | - Jeffery Ho
- Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, PR China; Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong, PR China
| | - William K K Wu
- Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, PR China; Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong, PR China
| | - Gary Tse
- Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong, PR China; Li Ka Shing Institute of Health Sciences, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, PR China.
| | - Sunny Hei Wong
- Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong, PR China; Li Ka Shing Institute of Health Sciences, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, PR China.
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16
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Huizinga JD. Recent advances in intestinal smooth muscle research: from muscle strips and single cells, via ICC networks to whole organ physiology and assessment of human gut motor dysfunction. J Smooth Muscle Res 2019; 55:68-80. [PMID: 31956167 PMCID: PMC6962316 DOI: 10.1540/jsmr.55.68] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Accepted: 11/01/2019] [Indexed: 12/12/2022] Open
Abstract
Gastrointestinal smooth muscle research has evolved from studies on muscle strips to spatiotemporal mapping of whole organ motor and electrical activities. Decades of research on single muscle cells and small sections of isolated musculature from animal models has given us the groundwork for interpretation of human in vivo studies. Human gut motility studies have dramatically improved by high-resolution manometry and high-resolution electrophysiology. The details that emerge from spatiotemporal mapping of high-resolution data are now of such quality that hypotheses can be generated as to the physiology (in healthy subjects) and pathophysiology (in patients) of gastrointestinal (dys) motility. Such interpretation demands understanding of the musculature as a super-network of excitable cells (neurons, smooth muscle cells, other accessory cells) and oscillatory cells (the pacemaker interstitial cells of Cajal), for which mathematical modeling becomes essential. The developing deeper understanding of gastrointestinal motility will bring us soon to a level of precision in diagnosis of dysfunction that is far beyond what is currently available.
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Affiliation(s)
- Jan D. Huizinga
- Department of Medicine-Gastroenterology, McMaster University,
Hamilton, Ontario, Canada
- Farncombe Family Digestive Health Research Institute,
Hamilton, Ontario, Canada
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17
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Abstract
Veins exhibit spontaneous contractile activity, a phenomenon generally termed vasomotion. This is mediated by spontaneous rhythmical contractions of mural cells (i.e. smooth muscle cells (SMCs) or pericytes) in the wall of the vessel. Vasomotion occurs through interconnected oscillators within and between mural cells, entraining their cycles. Pharmacological studies indicate that a key oscillator underlying vasomotion is the rhythmical calcium ion (Ca2+) release-refill cycle of Ca2+ stores. This occurs through opening of inositol 1,4,5-trisphosphate receptor (IP3R)- and/or ryanodine receptor (RyR)-operated Ca2+ release channels in the sarcoplasmic/endoplasmic (SR/ER) reticulum and refilling by the SR/ER reticulum Ca2+ATPase (SERCA). Released Ca2+ from stores near the plasma membrane diffuse through the cytosol to open Ca2+-activated chloride (Cl-) channels, this generating inward current through an efflux of Cl-. The resultant depolarisation leads to the opening of voltage-dependent Ca2+ channels and possibly increased production of IP3, which through Ca2+-induced Ca2+ release (CICR) of IP3Rs and/or RyRs and IP3R-mediated Ca2+ release provide a means by which store oscillators entrain their activity. Intercellular entrainment normally involves current flow through gap junctions that interconnect mural cells and in many cases this is aided by additional connectivity through the endothelium. Once entrainment has occurred the substantial Ca2+ entry that results from the near-synchronous depolarisations leads to rhythmical contractions of the mural cells, this often leading to vessel constriction. The basis for venous/venular vasomotion has yet to be fully delineated but could improve both venous drainage and capillary/venular absorption of blood plasma-associated fluids.
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18
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Vincent AD, Wang XY, Parsons SP, Khan WI, Huizinga JD. Abnormal absorptive colonic motor activity in germ-free mice is rectified by butyrate, an effect possibly mediated by mucosal serotonin. Am J Physiol Gastrointest Liver Physiol 2018; 315:G896-G907. [PMID: 30095295 DOI: 10.1152/ajpgi.00237.2017] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The role of short-chain fatty acids (SCFAs) in the control of colonic motility is controversial. Germ-free (GF) mice are unable to produce these metabolites and serve as a model to study how their absence affects colonic motility. GF transit is slower than controls, and colonization of these mice improves transit and serotonin [5-hydroxytryptamine (5-HT)] levels. Our aim was to determine the role SCFAs play in improving transit and whether this is dependent on mucosal 5-HT signaling. Motility was assessed in GF mice via spatiotemporal mapping. First, motor patterns in the whole colon were measured ex vivo with or without luminal SCFA, and outflow from the colon was recorded to quantify outflow caused by individual propulsive contractions. Second, artificial fecal pellet propulsion was measured. Motility was then assessed in tryptophan hydroxylase-1 (TPH1) knockout (KO) mice, devoid of mucosal 5-HT, with phosphate buffer, butyrate, or propionate intraluminal perfusion. GF mice exhibited a lower proportion of propulsive contractions, lower volume of outflow/contraction, slower velocity of contractions, and slower propulsion of fecal pellets compared with controls. SCFAs changed motility patterns to that of controls in all parameters. Butyrate administration increased the proportion of propulsive contractions in controls yet failed to in TPH1 KO mice. Propionate inhibited propulsive contractions in all mice. Our results reveal significant abnormalities in the propulsive nature of colonic motor patterns in GF mice, explaining the decreased transit time in in vivo studies. We show that butyrate but not propionate activates propulsive motility and that this may require mucosal 5-HT. NEW & NOTEWORTHY Understanding the role that the microbiota play in governing the physiology of colonic motility is lacking. Here, we offer for the first time, to our knowledge, a detailed analysis of colonic motor patterns and pellet propulsion using spatiotemporal mapping in the absence of microbiota. We show a striking difference in germ-free and control phenotypes and attribute this to a lack of fermentation-produced short-chain fatty acid. We then show that butyrate but not propionate can restore motility and that the butyrate effect likely requires mucosal 5-hydroxytryptamine.
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Affiliation(s)
- Alexander D Vincent
- Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University , Hamilton, Ontario , Canada
| | - Xuan-Yu Wang
- Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University , Hamilton, Ontario , Canada
| | - Sean P Parsons
- Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University , Hamilton, Ontario , Canada
| | - Waliul I Khan
- Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University , Hamilton, Ontario , Canada
| | - Jan D Huizinga
- Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University , Hamilton, Ontario , Canada
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19
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Parsons SP, Huizinga JD. Phase waves and trigger waves: emergent properties of oscillating and excitable networks in the gut. J Physiol 2018; 596:4819-4829. [PMID: 30055053 PMCID: PMC6187044 DOI: 10.1113/jp273425] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 07/18/2018] [Indexed: 12/30/2022] Open
Abstract
The gut is enmeshed by a number of cellular networks, but there is only a limited understanding of how these networks generate the complex patterns of activity that drive gut contractile functions. Here we review two fundamental types of cell behaviour, excitable and oscillating, and the patterns that networks of such cells generate, trigger waves and phase waves, respectively. We use both the language of biophysics and the theory of nonlinear dynamics to define these behaviours and understand how they generate patterns. Based on this we look for evidence of trigger and phase waves in the gut, including some of our recent work on the small intestine.
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Affiliation(s)
- Sean P. Parsons
- Farncombe Family Digestive Health Research InstituteDepartment of MedicineMcMaster UniversityHamiltonONCanada
| | - Jan D. Huizinga
- Farncombe Family Digestive Health Research InstituteDepartment of MedicineMcMaster UniversityHamiltonONCanada
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20
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O'Grady G, Angeli TR, Paskaranandavadivel N, Erickson JC, Wells CI, Gharibans AA, Cheng LK, Du P. Methods for High-Resolution Electrical Mapping in the Gastrointestinal Tract. IEEE Rev Biomed Eng 2018; 12:287-302. [PMID: 30176605 DOI: 10.1109/rbme.2018.2867555] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Over the last two decades, high-resolution (HR) mapping has emerged as a powerful technique to study normal and abnormal bioelectrical events in the gastrointestinal (GI) tract. This technique, adapted from cardiology, involves the use of dense arrays of electrodes to track bioelectrical sequences in fine spatiotemporal detail. HR mapping has now been applied in many significant GI experimental studies informing and clarifying both normal physiology and arrhythmic behaviors in disease states. This review provides a comprehensive and critical analysis of current methodologies for HR electrical mapping in the GI tract, including extracellular measurement principles, electrode design and mapping devices, signal processing and visualization techniques, and translational research strategies. The scope of the review encompasses the broad application of GI HR methods from in vitro tissue studies to in vivo experimental studies, including in humans. Controversies and future directions for GI mapping methodologies are addressed, including emerging opportunities to better inform diagnostics and care in patients with functional gut disorders of diverse etiologies.
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21
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Barth BB, Henriquez CS, Grill WM, Shen X. Electrical stimulation of gut motility guided by an in silico model. J Neural Eng 2018; 14:066010. [PMID: 28816177 DOI: 10.1088/1741-2552/aa86c8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Neuromodulation of the central and peripheral nervous systems is becoming increasingly important for treating a diverse set of diseases-ranging from Parkinson's Disease and epilepsy to chronic pain. However, neuromodulation of the gastrointestinal (GI) tract has achieved relatively limited success in treating functional GI disorders, which affect a significant population, because the effects of stimulation on the enteric nervous system (ENS) and gut motility are not well understood. Here we develop an integrated neuromechanical model of the ENS and assess neurostimulation strategies for enhancing gut motility, validated by in vivo experiments. APPROACH The computational model included a network of enteric neurons, smooth muscle fibers, and interstitial cells of Cajal, which regulated propulsion of a virtual pellet in a model of gut motility. MAIN RESULTS Simulated extracellular stimulation of ENS-mediated motility revealed that sinusoidal current at 0.5 Hz was more effective at increasing intrinsic peristalsis and reducing colon transit time than conventional higher frequency rectangular current pulses, as commonly used for neuromodulation therapy. Further analysis of the model revealed that the 0.5 Hz sinusoidal currents were more effective at modulating the pacemaker frequency of interstitial cells of Cajal. To test the predictions of the model, we conducted in vivo electrical stimulation of the distal colon while measuring bead propulsion in awake rats. Experimental results confirmed that 0.5 Hz sinusoidal currents were more effective than higher frequency pulses at enhancing gut motility. SIGNIFICANCE This work demonstrates an in silico GI neuromuscular model to enable GI neuromodulation parameter optimization and suggests that low frequency sinusoidal currents may improve the efficacy of GI pacing.
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Affiliation(s)
- Bradley B Barth
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America
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22
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Angeli TR, O'Grady G, Vather R, Bissett IP, Cheng LK. Intra-operative high-resolution mapping of slow wave propagation in the human jejunum: Feasibility and initial results. Neurogastroenterol Motil 2018; 30:e13310. [PMID: 29493080 DOI: 10.1111/nmo.13310] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 01/11/2018] [Indexed: 02/08/2023]
Abstract
BACKGROUND Bioelectrical slow waves are a coordinating mechanism of small intestine motility, but extracellular human studies have been restricted to a limited number of sparse electrode recordings. High-resolution (HR) mapping has offered substantial insights into spatiotemporal intestinal slow wave dynamics, but has been limited to animal studies to date. This study aimed to translate intra-operative HR mapping to define pacemaking and conduction profiles in the human small intestine. METHODS Immediately following laparotomy, flexible-printed-circuit arrays were applied around the serosa of the proximal jejunum (128-256 electrodes; 4-5.2 mm spacing; 28-59 cm2 ). Slow wave propagation patterns were mapped, and frequencies, amplitudes, downstroke widths, and velocities were calculated. Pacemaking and propagation patterns were defined. KEY RESULTS Analysis comprised nine patients with mean recording duration of 7.6 ± 2.8 minutes. Slow waves occurred at a frequency of 9.8 ± 0.4 cpm, amplitude 0.3 ± 0.04 mV, downstroke width 0.5 ± 0.1 seconds, and with faster circumferential velocity than longitudinal (10.1 ± 0.8 vs 9.0 ± 0.7 mm/s; P = .001). Focal pacemakers were identified and mapped (n = 4; mean frequency 9.9 ± 0.2 cpm). Disordered slow wave propagation was observed, including wavefront collisions, conduction blocks, and breakout and entrainment of pacemakers. CONCLUSIONS & INFERENCES This study introduces HR mapping of human intestinal slow waves, and provides first descriptions of intestinal pacemaker sites and velocity anisotropy. Future translation to other intestinal regions, disease states, and postsurgical dysmotility holds potential for improving the basic and clinical understanding of small intestine pathophysiology.
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Affiliation(s)
- T R Angeli
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - G O'Grady
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.,Department of Surgery, University of Auckland, Auckland, New Zealand
| | - R Vather
- Department of Surgery, University of Auckland, Auckland, New Zealand
| | - I P Bissett
- Department of Surgery, University of Auckland, Auckland, New Zealand
| | - L K Cheng
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.,Department of Surgery, Vanderbilt University, Nashville, TN, USA
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23
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Parsons SP, Huizinga JD. Slow wave contraction frequency plateaux in the small intestine are composed of discrete waves of interval increase associated with dislocations. Exp Physiol 2018; 103:1087-1100. [PMID: 29860720 DOI: 10.1113/ep086871] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 05/23/2018] [Indexed: 12/15/2022]
Abstract
NEW FINDINGS What is the central question of this study? What is the nature of slow wave-driven contraction frequency gradients in the small intestine? What is the main finding and its importance? Frequency plateaux are composed of discrete waves of increased interval, each wave associated with a contraction dislocation. Smooth frequency gradients are generated by localized neural modulation of wave frequency, leading to functionally important wave turbulence. Both patterns are emergent properties of a network of coupled oscillators, the interstitial cells of Cajal. ABSTRACT A gut-wide network of interstitial cells of Cajal generates electrical oscillations (slow waves) that orchestrate waves of muscle contraction. In the small intestine there is a gradient in slow wave frequency from high at the duodenum to low at the terminal ileum. Time-averaged measurements of frequency have suggested either a smooth or a stepped (plateaued) gradient. We measured individual contraction intervals from diameter maps of the mouse small intestine to create interval maps (IMaps). The IMaps showed that each frequency plateau was composed of discrete waves of increased interval. Each interval wave originated at a terminating contraction wave, a 'dislocation', at the proximal boundary of the plateau. In a model chain of coupled phase oscillators, interval wave frequency increased as coupling decreased or as the natural frequency gradient or noise increased. Injuring the intestine at a proximal point, to destroy coupling, suppressed distal steps, which then reappeared with gap junction block by carbenoxolone. This lent further support to our previous hypothesis that lines of dislocations were fixed by points of low coupling strength. Dislocations, induced by electrical field pulses in the intestine and by equivalent phase shift in the model, were associated with interval waves. When the enteric nervous system was active, IMaps showed a chaotic, turbulent pattern of interval change, with no frequency steps or plateaux. This probably resulted from local, stochastic release of neurotransmitters. Plateaux, dislocations, interval waves and wave turbulence arise from a dynamic interplay between natural frequency and coupling in the network of interstitial cells of Cajal.
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Affiliation(s)
- Sean P Parsons
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| | - Jan D Huizinga
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
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Lentle RG, Hulls CM. Quantifying Patterns of Smooth Muscle Motility in the Gut and Other Organs With New Techniques of Video Spatiotemporal Mapping. Front Physiol 2018; 9:338. [PMID: 29686624 PMCID: PMC5900429 DOI: 10.3389/fphys.2018.00338] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 03/20/2018] [Indexed: 01/12/2023] Open
Abstract
The uses and limitations of the various techniques of video spatiotemporal mapping based on change in diameter (D-type ST maps), change in longitudinal strain rate (L-type ST maps), change in area strain rate (A-type ST maps), and change in luminous intensity of reflected light (I-maps) are described, along with their use in quantifying motility of the wall of hollow structures of smooth muscle such as the gut. Hence ST-methods for determining the size, speed of propagation and frequency of contraction in the wall of gut compartments of differing geometric configurations are discussed. We also discuss the shortcomings and problems that are inherent in the various methods and the use of techniques to avoid or minimize them. This discussion includes, the inability of D-type ST maps to indicate the site of a contraction that does not reduce the diameter of a gut segment, the manipulation of axis [the line of interest (LOI)] of L-maps to determine the true axis of propagation of a contraction, problems with anterior curvature of gut segments and the use of adjunct image analysis techniques that enhance particular features of the maps.
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Affiliation(s)
- Roger G Lentle
- Physiology Department, Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
| | - Corrin M Hulls
- Physiology Department, Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
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25
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Parsons SP, Huizinga JD. The phase response and state space of slow wave contractions in the small intestine. Exp Physiol 2017; 102:1118-1132. [DOI: 10.1113/ep086373] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 06/29/2017] [Indexed: 12/28/2022]
Affiliation(s)
- Sean P. Parsons
- Farncombe Family Digestive Health Research Institute; McMaster University; Hamilton Ontario Canada
| | - Jan D. Huizinga
- Farncombe Family Digestive Health Research Institute; McMaster University; Hamilton Ontario Canada
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26
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Relationships between motor patterns and intraluminal pressure in the 3-taeniated proximal colon of the rabbit. Sci Rep 2017; 7:42293. [PMID: 28195136 PMCID: PMC5307310 DOI: 10.1038/srep42293] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 01/09/2017] [Indexed: 12/12/2022] Open
Abstract
Manometry is used worldwide to assess motor function of the gastrointestinal tract, and the measured intraluminal pressure patterns are usually equated with contraction patterns. In the colon, simultaneous pressure increases throughout the entire colon are most often called simultaneous contractions, although this inference has never been verified. To evaluate the relationship between pressure and contraction in the colon we performed high-resolution manometry and measured diameter changes reflecting circular muscle contractions in the rabbit colon. We show that within a certain range of contraction amplitudes and frequencies, the intraluminal pressure pattern faithfully resembles the contraction pattern. However, when the frequency is very high (as in fast propagating contractions in a cluster) the consequent intraluminal pressures merge. When the contraction speed of propagation is very fast (above ~5 cm/s), the resulting pressure occurs simultaneous throughout the colon; hence simultaneous pressure is measured as are caused by fast propagating contractions. The very slow propagating, low amplitude haustral boundary contractions show a very characteristic pattern in spatiotemporal contraction maps that is not faithfully reproduced in the pressure maps. Correct interpretation of pressure events in high-resolution manometry is essential to make it a reliable tool for diagnosis and management of patients with colon motor dysfunction.
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Wei R, Parsons SP, Huizinga JD. Network properties of interstitial cells of Cajal affect intestinal pacemaker activity and motor patterns, according to a mathematical model of weakly coupled oscillators. Exp Physiol 2017; 102:329-346. [DOI: 10.1113/ep086077] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Accepted: 12/15/2016] [Indexed: 12/13/2022]
Affiliation(s)
- Ruihan Wei
- McMaster University, Department of Medicine; Farncombe Family Digestive Health Research Institute; Hamilton ON Canada
| | - Sean P. Parsons
- McMaster University, Department of Medicine; Farncombe Family Digestive Health Research Institute; Hamilton ON Canada
| | - Jan D. Huizinga
- McMaster University, Department of Medicine; Farncombe Family Digestive Health Research Institute; Hamilton ON Canada
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Berry R, Miyagawa T, Paskaranandavadivel N, Du P, Angeli TR, Trew ML, Windsor JA, Imai Y, O'Grady G, Cheng LK. Functional physiology of the human terminal antrum defined by high-resolution electrical mapping and computational modeling. Am J Physiol Gastrointest Liver Physiol 2016; 311:G895-G902. [PMID: 27659422 PMCID: PMC5130547 DOI: 10.1152/ajpgi.00255.2016] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 09/14/2016] [Indexed: 01/31/2023]
Abstract
High-resolution (HR) mapping has been used to study gastric slow-wave activation; however, the specific characteristics of antral electrophysiology remain poorly defined. This study applied HR mapping and computational modeling to define functional human antral physiology. HR mapping was performed in 10 subjects using flexible electrode arrays (128-192 electrodes; 16-24 cm2) arranged from the pylorus to mid-corpus. Anatomical registration was by photographs and anatomical landmarks. Slow-wave parameters were computed, and resultant data were incorporated into a computational fluid dynamics (CFD) model of gastric flow to calculate impact on gastric mixing. In all subjects, extracellular mapping demonstrated normal aboral slow-wave propagation and a region of increased amplitude and velocity in the prepyloric antrum. On average, the high-velocity region commenced 28 mm proximal to the pylorus, and activation ceased 6 mm from the pylorus. Within this region, velocity increased 0.2 mm/s per mm of tissue, from the mean 3.3 ± 0.1 mm/s to 7.5 ± 0.6 mm/s (P < 0.001), and extracellular amplitude increased from 1.5 ± 0.1 mV to 2.5 ± 0.1 mV (P < 0.001). CFD modeling using representative parameters quantified a marked increase in antral recirculation, resulting in an enhanced gastric mixing, due to the accelerating terminal antral contraction. The extent of gastric mixing increased almost linearly with the maximal velocity of the contraction. In conclusion, the human terminal antral contraction is controlled by a short region of rapid high-amplitude slow-wave activity. Distal antral wave acceleration plays a major role in antral flow and mixing, increasing particle strain and trituration.
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Affiliation(s)
- Rachel Berry
- 1Auckland Bioengineering Institute, University of Auckland, Aukland, New Zealand;
| | - Taimei Miyagawa
- 2Department of Biomedical Engineering, Tohoku University, Sendai, Japan;
| | | | - Peng Du
- 1Auckland Bioengineering Institute, University of Auckland, Aukland, New Zealand;
| | - Timothy R. Angeli
- 1Auckland Bioengineering Institute, University of Auckland, Aukland, New Zealand;
| | - Mark L. Trew
- 1Auckland Bioengineering Institute, University of Auckland, Aukland, New Zealand;
| | - John A. Windsor
- 3Department of Surgery, University of Auckland, Auckland, New Zealand;
| | - Yohsuke Imai
- 4School of Engineering, Tohoku University, Sendai, Japan; and
| | - Gregory O'Grady
- 1Auckland Bioengineering Institute, University of Auckland, Aukland, New Zealand; ,3Department of Surgery, University of Auckland, Auckland, New Zealand;
| | - Leo K. Cheng
- 1Auckland Bioengineering Institute, University of Auckland, Aukland, New Zealand; ,5Department of Surgery, Vanderbilt University, Nashville, Tennessee
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Zhu YF, Wang XY, Parsons SP, Huizinga JD. Stimulus-induced pacemaker activity in interstitial cells of Cajal associated with the deep muscular plexus of the small intestine. Neurogastroenterol Motil 2016; 28:1064-74. [PMID: 26968691 DOI: 10.1111/nmo.12808] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 02/01/2016] [Indexed: 02/08/2023]
Abstract
BACKGROUND The ICC-DMP have been proposed to generate stimulus-dependent pacemaker activity, rhythmic transient depolarizations, that take part in orchestrating segmentation and clustered propulsive motor patterns in the small intestine. However, little is known about the fundamental properties of ICC-DMP. METHODS This study was undertaken to increase our understanding of intrinsic properties of the ICC-DMP through calcium imaging and intracellular electrical recordings. KEY RESULTS Without stimulation, most ICC-DMP were quiescent. In some preparations ICC-DMP generated rhythmic low-frequency calcium oscillations (<10 cpm) with or without high frequency activity superimposed (>35 cpm). Immunohistochemistry proved the existence of NK1R on the ICC-DMP and close contacts between ICC-DMP and substance P-positive nerves. Substance P (25 nM) induced low-frequency calcium oscillations that were synchronized across the ICC-DMP network. Substance P also induced low frequency rhythmic transient depolarizations (<10cpm) in circular muscle cells close to the ICC-DMP. An intracellular recording from a positively identified ICC-DMP showed rhythmic transient depolarizations with superimposed high frequency activity. To investigate if quiescent ICC-DMP were chronically inhibited by nitrergic activity, nNOS was inhibited, but without effect. CONCLUSIONS & INFERENCES Substance P changes non-synchronized high frequency flickering or quiescence in ICC-DMP into strong rhythmic calcium transients that are synchronized within the network; they are associated with rhythmic transient depolarizations within the same frequency range. We hypothesize that Substance P, released from nerves, can evoke rhythmicity in ICC-DMP, thereby providing it with potential pacemaker activity.
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Affiliation(s)
- Y F Zhu
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| | - X-Y Wang
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| | - S P Parsons
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| | - J D Huizinga
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
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30
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Mitrou N, Braam B, Cupples WA. A gap junction inhibitor, carbenoxolone, induces spatiotemporal dispersion of renal cortical perfusion and impairs autoregulation. Am J Physiol Heart Circ Physiol 2016; 311:H582-91. [PMID: 27371687 DOI: 10.1152/ajpheart.00941.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 06/27/2016] [Indexed: 11/22/2022]
Abstract
Renal autoregulation dynamics originating from the myogenic response (MR) and tubuloglomerular feedback (TGF) can synchronize over large regions of the kidney surface, likely through gap junction-mediated electrotonic conduction and reflecting distributed operation of autoregulation. We tested the hypotheses that inhibition of gap junctions reduces spatial synchronization of autoregulation dynamics, abrogates spatial and temporal smoothing of renal perfusion, and impairs renal autoregulation. In male Long-Evans rats, we infused the gap junction inhibitor carbenoxolone (CBX) or the related glycyrrhizic acid (GZA) that does not block gap junctions into the renal artery and monitored renal blood flow (RBF) and surface perfusion by laser speckle contrast imaging. Neither CBX nor GZA altered RBF or mean surface perfusion. CBX preferentially increased spatial and temporal variation in the distribution of surface perfusion, increased spatial variation in the operating frequencies of the MR and TGF, and reduced phase coherence of TGF and increased its dispersion. CBX, but not GZA, impaired dynamic and steady-state autoregulation. Separately, infusion of the Rho kinase inhibitor Y-27632 paralyzed smooth muscle, grossly impaired dynamic autoregulation, and monotonically increased spatial variation of surface perfusion. These data suggest CBX inhibited gap junction communication, which in turn reduced the ability of TGF to synchronize among groups of nephrons. The results indicate that impaired autoregulation resulted from degraded synchronization, rather than the reverse. We show that network behavior in the renal vasculature is necessary for effective RBF autoregulation.
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Affiliation(s)
- Nicholas Mitrou
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada; and
| | - Branko Braam
- Department of Physiology and Department of Medicine, Division of Nephrology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - William A Cupples
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada; and
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31
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Tse G, Lai ETH, Yeo JM, Tse V, Wong SH. Mechanisms of Electrical Activation and Conduction in the Gastrointestinal System: Lessons from Cardiac Electrophysiology. Front Physiol 2016; 7:182. [PMID: 27303305 PMCID: PMC4885840 DOI: 10.3389/fphys.2016.00182] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 05/06/2016] [Indexed: 12/12/2022] Open
Abstract
The gastrointestinal (GI) tract is an electrically excitable organ system containing multiple cell types, which coordinate electrical activity propagating through this tract. Disruption in its normal electrophysiology is observed in a number of GI motility disorders. However, this is not well characterized and the field of GI electrophysiology is much less developed compared to the cardiac field. The aim of this article is to use the established knowledge of cardiac electrophysiology to shed light on the mechanisms of electrical activation and propagation along the GI tract, and how abnormalities in these processes lead to motility disorders and suggest better treatment options based on this improved understanding. In the first part of the article, the ionic contributions to the generation of GI slow wave and the cardiac action potential (AP) are reviewed. Propagation of these electrical signals can be described by the core conductor theory in both systems. However, specifically for the GI tract, the following unique properties are observed: changes in slow wave frequency along its length, periods of quiescence, synchronization in short distances and desynchronization over long distances. These are best described by a coupled oscillator theory. Other differences include the diminished role of gap junctions in mediating this conduction in the GI tract compared to the heart. The electrophysiology of conditions such as gastroesophageal reflux disease and gastroparesis, and functional problems such as irritable bowel syndrome are discussed in detail, with reference to ion channel abnormalities and potential therapeutic targets. A deeper understanding of the molecular basis and physiological mechanisms underlying GI motility disorders will enable the development of better diagnostic and therapeutic tools and the advancement of this field.
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Affiliation(s)
- Gary Tse
- Li Ka Shing Faculty of Medicine, School of Biomedical Sciences, University of Hong KongHong Kong, China
| | - Eric Tsz Him Lai
- Li Ka Shing Faculty of Medicine, School of Biomedical Sciences, University of Hong KongHong Kong, China
| | - Jie Ming Yeo
- School of Medicine, Imperial College LondonLondon, UK
| | - Vivian Tse
- Department of Physiology, McGill UniversityMontreal, QC, Canada
| | - Sunny Hei Wong
- Department of Medicine and Therapeutics, Institute of Digestive Disease, LKS Institute of Health Sciences, Chinese University of Hong KongHong Kong, China
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32
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Baker SA, Drumm BT, Saur D, Hennig GW, Ward SM, Sanders KM. Spontaneous Ca(2+) transients in interstitial cells of Cajal located within the deep muscular plexus of the murine small intestine. J Physiol 2016; 594:3317-38. [PMID: 26824875 DOI: 10.1113/jp271699] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 01/24/2016] [Indexed: 01/13/2023] Open
Abstract
KEY POINTS Interstitial cells of Cajal at the level of the deep muscular plexus (ICC-DMP) in the small intestine generate spontaneous Ca(2+) transients that consist of localized Ca(2+) events and limited propagating Ca(2+) waves. Ca(2+) transients in ICC-DMP display variable characteristics: from discrete, highly localized Ca(2+) transients to regionalized Ca(2+) waves with variable rates of occurrence, amplitude, duration and spatial spread. Ca(2+) transients fired stochastically, with no cellular or multicellular rhythmic activity being observed. No correlation was found between the firing sites in adjacent cells. Ca(2+) transients in ICC-DMP are suppressed by the ongoing release of inhibitory neurotransmitter(s). Functional intracellular Ca(2+) stores are essential for spontaneous Ca(2+) transients, and the sarco/endoplasmic reticulum Ca(2+) -ATPase (SERCA) pump is necessary for maintenance of spontaneity. Ca(2+) release mechanisms involve both ryanodine receptors (RyRs) and inositol triphosphate receptors (InsP3 Rs). Release from these channels is interdependent. ICC express transcripts of multiple RyRs and InsP3 Rs, with Itpr1 and Ryr2 subtypes displaying the highest expression. ABSTRACT Interstitial cells of Cajal in the deep muscular plexus of the small intestine (ICC-DMP) are closely associated with varicosities of enteric motor neurons and generate responses contributing to neural regulation of intestinal motility. Responses of ICC-DMP are mediated by activation of Ca(2+) -activated Cl(-) channels; thus, Ca(2+) signalling is central to the behaviours of these cells. Confocal imaging was used to characterize the nature and mechanisms of Ca(2+) transients in ICC-DMP within intact jejunal muscles expressing a genetically encoded Ca(2+) indicator (GCaMP3) selectively in ICC. ICC-DMP displayed spontaneous Ca(2+) transients that ranged from discrete, localized events to waves that propagated over variable distances. The occurrence of Ca(2+) transients was highly variable, and it was determined that firing was stochastic in nature. Ca(2+) transients were tabulated in multiple cells within fields of view, and no correlation was found between the events in adjacent cells. TTX (1 μm) significantly increased the occurrence of Ca(2+) transients, suggesting that ICC-DMP contributes to the tonic inhibition conveyed by ongoing activity of inhibitory motor neurons. Ca(2+) transients were minimally affected after 12 min in Ca(2+) free solution, indicating these events do not depend immediately upon Ca(2+) influx. However, inhibitors of sarco/endoplasmic reticulum Ca(2+) -ATPase (SERCA) pump and blockers of inositol triphosphate receptor (InsP3 R) and ryanodine receptor (RyR) channels blocked ICC Ca(2+) transients. These data suggest an interdependence between RyR and InsP3 R in the generation of Ca(2+) transients. Itpr1 and Ryr2 were the dominant transcripts expressed by ICC. These findings provide the first high-resolution recording of the subcellular Ca(2+) dynamics that control the behaviour of ICC-DMP in situ.
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Affiliation(s)
- Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Dieter Saur
- II. Medizinische Klinik und Poliklinik, Klinikum rechts der Isar der TU München, München, Germany
| | - Grant W Hennig
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
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33
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Parsons SP, Huizinga JD. Spatial Noise in Coupling Strength and Natural Frequency within a Pacemaker Network; Consequences for Development of Intestinal Motor Patterns According to a Weakly Coupled Phase Oscillator Model. Front Neurosci 2016; 10:19. [PMID: 26869875 PMCID: PMC4740389 DOI: 10.3389/fnins.2016.00019] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 01/15/2016] [Indexed: 12/11/2022] Open
Abstract
Pacemaker activities generated by networks of interstitial cells of Cajal (ICC), in conjunction with the enteric nervous system, orchestrate most motor patterns in the gastrointestinal tract. It was our objective to understand the role of network features of ICC associated with the myenteric plexus (ICC-MP) in the shaping of motor patterns of the small intestine. To that end, a model of weakly coupled oscillators (oscillators influence each other's phase but not amplitude) was created with most parameters derived from experimental data. The ICC network is a uniform two dimensional network coupled by gap junctions. All ICC generate pacemaker (slow wave) activity with a frequency gradient in mice from 50/min at the proximal end of the intestine to 40/min at the distal end. Key features of motor patterns, directly related to the underlying pacemaker activity, are frequency steps and dislocations. These were accurately mimicked by reduction of coupling strength at a point in the chain of oscillators. When coupling strength was expressed as a product of gap junction density and conductance, and gap junction density was varied randomly along the chain (i.e., spatial noise) with a long-tailed distribution, plateau steps occurred at pointsof low density. As gap junction conductance was decreased, the number of plateaus increased, mimicking the effect of the gap junction inhibitor carbenoxolone. When spatial noise was added to the natural interval gradient, as gap junction conductance decreased, the number of plateaus increased as before but in addition the phase waves frequently changed direction of apparent propagation, again mimicking the effect of carbenoxolone. In summary, key features of the motor patterns that are governed by pacemaker activity may be a direct consequence of biological noise, specifically spatial noise in gap junction coupling and pacemaker frequency.
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Affiliation(s)
- Sean P Parsons
- Department of Medicine, Farncombe Family Digestive Health Institute, McMaster University Hamilton, ON, Canada
| | - Jan D Huizinga
- Department of Medicine, Farncombe Family Digestive Health Institute, McMaster University Hamilton, ON, Canada
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34
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Chen JH, Yang Z, Yu Y, Huizinga JD. Haustral boundary contractions in the proximal 3-taeniated rabbit colon. Am J Physiol Gastrointest Liver Physiol 2016; 310:G181-92. [PMID: 26635318 DOI: 10.1152/ajpgi.00171.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 11/19/2015] [Indexed: 02/06/2023]
Abstract
The rabbit proximal colon is similar in structure to the human colon. Our objective was to study interactions of different rhythmic motor patterns focusing on haustral boundary contractions, which create the haustra, using spatiotemporal mapping of video recordings. Haustral boundary contractions were seen as highly rhythmic circumferential ring contractions that propagated slowly across the proximal colon, preferentially but not exclusively in the anal direction, at ∼0.5 cycles per minute; they were abolished by nerve conduction blockers. When multiple haustral boundary contractions propagated in the opposite direction, they annihilated each other upon encounter. Ripples, myogenic propagating ring contractions at ∼9 cycles per min, induced folding and unfolding of haustral muscle folds, creating an anarchic appearance of contractile activity, with different patterns in the three intertaenial regions. Two features of ripple activity were prominent: frequent changes in propagation direction and the occurrence of dislocations showing a frequency gradient with the highest intrinsic frequency in the distal colon. The haustral boundary contractions showed an on/off/on/off pattern at the ripple frequency, and the contraction amplitude at any point of the colon showed waxing and waning. The haustral boundary contractions are therefore shaped by interaction of two pacemaker activities hypothesized to occur through phase-amplitude coupling of pacemaker activities from interstitial cells of Cajal of the myenteric plexus and of the submuscular plexus. Video evidence shows the unique role haustral folds play in shaping contractile activity within the haustra. Muscarinic agents not only enhance the force of contraction, they can eliminate one and at the same time induce another neurally dependent motor pattern.
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Affiliation(s)
- Ji-Hong Chen
- Department of Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Key Laboratory of Hubei Province for Digestive System Diseases, Wuhan, Hubei Province, China; and Farncombe Family Digestive Health Research Institute, McMaster University Department of Medicine, Hamilton, Ontario, Canada
| | - Zixian Yang
- Department of Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Key Laboratory of Hubei Province for Digestive System Diseases, Wuhan, Hubei Province, China; and
| | - Yuanjie Yu
- Department of Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Key Laboratory of Hubei Province for Digestive System Diseases, Wuhan, Hubei Province, China; and
| | - Jan D Huizinga
- Department of Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Key Laboratory of Hubei Province for Digestive System Diseases, Wuhan, Hubei Province, China; and Farncombe Family Digestive Health Research Institute, McMaster University Department of Medicine, Hamilton, Ontario, Canada
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35
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Du P, Paskaranandavadivel N, Angeli TR, Cheng LK, O'Grady G. The virtual intestine: in silico modeling of small intestinal electrophysiology and motility and the applications. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2015; 8:69-85. [PMID: 26562482 DOI: 10.1002/wsbm.1324] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 10/01/2015] [Accepted: 10/02/2015] [Indexed: 02/06/2023]
Abstract
The intestine comprises a long hollow muscular tube organized in anatomically and functionally discrete compartments, which digest and absorb nutrients and water from ingested food. The intestine also plays key roles in the elimination of waste and protection from infection. Critical to all of these functions is the intricate, highly coordinated motion of the intestinal tract, known as motility, which is coregulated by hormonal, neural, electrophysiological and other factors. The Virtual Intestine encapsulates a series of mathematical models of intestinal function in health and disease, with a current focus on motility, and particularly electrophysiology. The Virtual Intestine is being cohesively established across multiple physiological scales, from sub/cellular functions to whole organ levels, facilitating quantitative evaluations that present an integrative in silico framework. The models are also now finding broad physiological applications, including in evaluating hypotheses of slow wave pacemaker mechanisms, smooth muscle electrophysiology, structure-function relationships, and electromechanical coupling. Clinical applications are also beginning to follow, including in the pathophysiology of motility disorders, diagnosing intestinal ischemia, and visualizing colonic dysfunction. These advances illustrate the emerging potential of the Virtual Intestine to effectively address multiscale research challenges in interdisciplinary gastrointestinal sciences.
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Affiliation(s)
- Peng Du
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | | | - Timothy R Angeli
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Leo K Cheng
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Gregory O'Grady
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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36
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Huizinga JD, Parsons SP, Chen JH, Pawelka A, Pistilli M, Li C, Yu Y, Ye P, Liu Q, Tong M, Zhu YF, Wei D. Motor patterns of the small intestine explained by phase-amplitude coupling of two pacemaker activities: the critical importance of propagation velocity. Am J Physiol Cell Physiol 2015; 309:C403-14. [PMID: 26135802 DOI: 10.1152/ajpcell.00414.2014] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 06/26/2015] [Indexed: 12/23/2022]
Abstract
Phase-amplitude coupling of two pacemaker activities of the small intestine, the omnipresent slow wave activity generated by interstitial cells of Cajal of the myenteric plexus (ICC-MP) and the stimulus-dependent rhythmic transient depolarizations generated by ICC of the deep muscular plexus (ICC-DMP), was recently hypothesized to underlie the orchestration of the segmentation motor pattern. The aim of the present study was to increase our understanding of phase-amplitude coupling through modeling. In particular the importance of propagation velocity of the ICC-DMP component was investigated. The outcome of the modeling was compared with motor patterns recorded from the rat or mouse intestine from which propagation velocities within the different patterns were measured. The results show that the classical segmentation motor pattern occurs when the ICC-DMP component has a low propagation velocity (<0.05 cm/s). When the ICC-DMP component has a propagation velocity in the same order of magnitude as that of the slow wave activity (∼1 cm/s), cluster type propulsive activity occurs which is in fact the dominant propulsive activity of the intestine. Hence, the only difference between the generation of propagating cluster contractions and the Cannon-type segmentation motor pattern is the propagation velocity of the low-frequency component, the rhythmic transient depolarizations originating from the ICC-DMP. Importantly, the proposed mechanism explains why both motor patterns have distinct rhythmic waxing and waning of the amplitude of contractions. The hypothesis is brought forward that the velocity is modulated by neural regulation of gap junction conductance within the ICC-DMP network.
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Affiliation(s)
- Jan D Huizinga
- Farncombe Family Digestive Health Research Institute, Department of Medicine, McMaster University, Hamilton, Canada; and Department of Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Wuhan University Institute of Digestive and Liver Diseases, Key Laboratory of Hubei Province for Digestive System Diseases, Wuhan, China
| | - Sean P Parsons
- Farncombe Family Digestive Health Research Institute, Department of Medicine, McMaster University, Hamilton, Canada; and
| | - Ji-Hong Chen
- Farncombe Family Digestive Health Research Institute, Department of Medicine, McMaster University, Hamilton, Canada; and Department of Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Wuhan University Institute of Digestive and Liver Diseases, Key Laboratory of Hubei Province for Digestive System Diseases, Wuhan, China
| | - Andrew Pawelka
- Farncombe Family Digestive Health Research Institute, Department of Medicine, McMaster University, Hamilton, Canada; and
| | - Marc Pistilli
- Farncombe Family Digestive Health Research Institute, Department of Medicine, McMaster University, Hamilton, Canada; and
| | - Chunpei Li
- Department of Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Wuhan University Institute of Digestive and Liver Diseases, Key Laboratory of Hubei Province for Digestive System Diseases, Wuhan, China
| | - Yuanjie Yu
- Department of Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Wuhan University Institute of Digestive and Liver Diseases, Key Laboratory of Hubei Province for Digestive System Diseases, Wuhan, China
| | - Pengfei Ye
- Department of Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Wuhan University Institute of Digestive and Liver Diseases, Key Laboratory of Hubei Province for Digestive System Diseases, Wuhan, China
| | - Qing Liu
- Department of Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Wuhan University Institute of Digestive and Liver Diseases, Key Laboratory of Hubei Province for Digestive System Diseases, Wuhan, China
| | - Mengting Tong
- Department of Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Wuhan University Institute of Digestive and Liver Diseases, Key Laboratory of Hubei Province for Digestive System Diseases, Wuhan, China
| | - Yong Fang Zhu
- Farncombe Family Digestive Health Research Institute, Department of Medicine, McMaster University, Hamilton, Canada; and
| | - Defei Wei
- Department of Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Wuhan University Institute of Digestive and Liver Diseases, Key Laboratory of Hubei Province for Digestive System Diseases, Wuhan, China
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37
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Pawelka AJ, Huizinga JD. Induction of rhythmic transient depolarizations associated with waxing and waning of slow wave activity in intestinal smooth muscle. Am J Physiol Gastrointest Liver Physiol 2015; 308:G427-33. [PMID: 25540235 DOI: 10.1152/ajpgi.00409.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cannon described in 1902 the segmentation motor activity of the small intestine (Canon WB. J Med Res 7: 72-75, 1902). This motor pattern can arise when low-frequency transient depolarizations are evoked in the interstitial cells of Cajal associated with the deep muscular plexus (ICC-DMP) network, which then affect the omnipresent slow wave activity: changing its regular amplitude into a waxing and waning pattern. The objective of the present study was to investigate physiological stimuli that could induce the low-frequency component. Intracellular recordings were obtained from circular muscle with or without attached mucosa. Decanoic acid (1 mM) and butyric acid (10 mM) both evoked low-frequency transient depolarizations but through different mechanisms. Decanoic acid-induced waxing and waning was initiated by purely myogenic means when perfused onto exposed circular muscle. Butyric acid required the intact mucosa and uninhibited neural activity to elicit the low-frequency response. Evidence is provided that the transient rhythmic depolarizations occur in the absence of interstitial cells of Cajal associated with the myenteric plexus (ICC-MP). Onset of the slow transient depolarizations was stimulated by addition of N(ω)-nitro-l-arginine (l-NNA; 100 μM); thus the low-frequency component seems to be under chronic inhibition by nitric oxide. Excitatory tachykinergic stimulation induced the low-frequency component since substance P (0.5 μM) evoked it in the presence of neural blockade. In summary, interplay between two networks of myogenic pacemakers, neural activity, and nutrient factors such as fatty acids plays a role in the generation of the rhythmic low-frequency component that is essential for the development of the checkered segmentation motor pattern.
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Affiliation(s)
- Andrew J Pawelka
- Farncombe Family Digestive Health Research Institute, Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Jan D Huizinga
- Farncombe Family Digestive Health Research Institute, Department of Medicine, McMaster University, Hamilton, Ontario, Canada
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