1
|
Baker SA, Leigh WA, Del Valle G, De Yturriaga IF, Ward SM, Cobine CA, Drumm BT, Sanders KM. Ca 2+ signaling driving pacemaker activity in submucosal interstitial cells of Cajal in the murine colon. eLife 2021; 10:64099. [PMID: 33399536 PMCID: PMC7806270 DOI: 10.7554/elife.64099] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 01/04/2021] [Indexed: 02/06/2023] Open
Abstract
Interstitial cells of Cajal (ICC) generate pacemaker activity responsible for phasic contractions in colonic segmentation and peristalsis. ICC along the submucosal border (ICC-SM) contribute to mixing and more complex patterns of colonic motility. We show the complex patterns of Ca2+ signaling in ICC-SM and the relationship between ICC-SM Ca2+ transients and activation of smooth muscle cells (SMCs) using optogenetic tools. ICC-SM displayed rhythmic firing of Ca2+transients ~ 15 cpm and paced adjacent SMCs. The majority of spontaneous activity occurred in regular Ca2+ transients clusters (CTCs) that propagated through the network. CTCs were organized and dependent upon Ca2+ entry through voltage-dependent Ca2+ conductances, L- and T-type Ca2+ channels. Removal of Ca2+ from the external solution abolished CTCs. Ca2+ release mechanisms reduced the duration and amplitude of Ca2+ transients but did not block CTCs. These data reveal how colonic pacemaker ICC-SM exhibit complex Ca2+-firing patterns and drive smooth muscle activity and overall colonic contractions.
Collapse
Affiliation(s)
- Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada, Reno, School of Medicine, Reno, United States
| | - Wesley A Leigh
- Department of Physiology and Cell Biology, University of Nevada, Reno, School of Medicine, Reno, United States
| | - Guillermo Del Valle
- Department of Physiology and Cell Biology, University of Nevada, Reno, School of Medicine, Reno, United States
| | - Inigo F De Yturriaga
- Department of Physiology and Cell Biology, University of Nevada, Reno, School of Medicine, Reno, United States
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada, Reno, School of Medicine, Reno, United States
| | - Caroline A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno, School of Medicine, Reno, United States
| | - Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada, Reno, School of Medicine, Reno, United States
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada, Reno, School of Medicine, Reno, United States
| |
Collapse
|
2
|
Mah SA, Avci R, Cheng LK, Du P. Current applications of mathematical models of the interstitial cells of Cajal in the gastrointestinal tract. WIREs Mech Dis 2020; 13:e1507. [PMID: 33026190 DOI: 10.1002/wsbm.1507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 08/31/2020] [Accepted: 09/04/2020] [Indexed: 12/25/2022]
Abstract
The interstitial cells of Cajal (ICC) form interconnected networks throughout the gastrointestinal (GI) tract. ICC act as the pacemaker cells that initiate the rhythmic bioelectrical slow waves and intermediary between the GI musculature and nerves, both of which are critical to GI motility. Disruptions to the number of ICC and the integrity of ICC networks have been identified as a key pathophysiological mechanism in a number of clinically challenging GI disorders. The current analyses of ICC generally rely on either functional recordings taken directly from excised tissue or morphological analysis based on images of labeled ICC, where the structural-functional relationship is investigated in an associative manner rather than mechanistically. On the other hand, computational physiology has played a significant role in facilitating our understanding of a number of physiological systems in both health and disease, and investigations in the GI field are beginning to incorporate several mathematical models of the ICC. The main aim of this review is to present the major modeling advances in GI electrophysiology, in order to introduce a multi-scale framework for mathematically quantifying the functional consequences of ICC degradation at both cellular and tissue scales. The outcomes will inform future investigators utilizing modeling techniques in their studies. This article is categorized under: Metabolic Diseases > Computational Models.
Collapse
Affiliation(s)
- Sue Ann Mah
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Recep Avci
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Leo K Cheng
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Peng Du
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.,Department of Engineering Science, University of Auckland, Auckland, New Zealand
| |
Collapse
|
3
|
Costa M, Hibberd TJ, Keightley LJ, Wiklendt L, Arkwright JW, Dinning PG, Brookes SJH, Spencer NJ. Neural motor complexes propagate continuously along the full length of mouse small intestine and colon. Am J Physiol Gastrointest Liver Physiol 2020; 318:G99-G108. [PMID: 31709829 DOI: 10.1152/ajpgi.00185.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cyclical propagating waves of muscle contraction have been recorded in isolated small intestine or colon, referred to here as motor complexes (MCs). Small intestinal and colonic MCs are neurogenic, occur at similar frequencies, and propagate orally or aborally. Whether they can be coordinated between the different gut regions is unclear. Motor behavior of whole length mouse intestines, from duodenum to terminal rectum, was recorded by intraluminal multisensor catheter. Small intestinal MCs were recorded in 27/30 preparations, and colonic MCs were recorded in all preparations (n = 30) with similar frequencies (0.54 ± 0.03 and 0.58 ± 0.02 counts/min, respectively). MCs propagated across the ileo-colonic junction in 10/30 preparations, forming "full intestine" MCs. The cholinesterase inhibitor physostigmine increased the probability of a full intestine MC but had no significant effect on frequency, speed, or direction. Nitric oxide synthesis blockade by Nω-nitro-l-arginine, after physostigmine, increased MC frequency in small intestine only. Hyoscine-resistant MCs were recorded in the colon but not small intestine (n = 5). All MCs were abolished by hexamethonium (n = 18) or tetrodotoxin (n = 2). The enteric neural mechanism required for motor complexes is present along the full length of both the small and large intestine. In some cases, colonic MCs can be initiated in the distal colon and propagate through the ileo-colonic junction, all the way to duodenum. In conclusion, the ileo-colonic junction provides functional neural continuity for propagating motor activity that originates in the small or large intestine.NEW & NOTEWORTHY Intraluminal manometric recordings revealed motor complexes can propagate antegradely or retrogradely across the ileo-colonic junction, spanning the entire small and large intestines. The fundamental enteric neural mechanism(s) underlying cyclic motor complexes exists throughout the length of the small and large intestine.
Collapse
Affiliation(s)
- Marcello Costa
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University, Adelaide, South Australia, Australia
| | - Timothy James Hibberd
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University, Adelaide, South Australia, Australia
| | - Lauren J Keightley
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University, Adelaide, South Australia, Australia
| | - Lukasz Wiklendt
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University, Adelaide, South Australia, Australia
| | - John W Arkwright
- Computer Science, Engineering and Mathematics, Flinders University, Adelaide, South Australia, Australia
| | - Philip G Dinning
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University, Adelaide, South Australia, Australia.,Department of Gastroenterology and Surgery, Flinders Medical Centre, Flinders University, Adelaide, South Australia, Australia
| | - Simon J H Brookes
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University, Adelaide, South Australia, Australia
| | - Nick J Spencer
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University, Adelaide, South Australia, Australia
| |
Collapse
|
4
|
Use of a microelectrode array to record extracellular pacemaker potentials from the gastrointestinal tracts of the ICR mouse and house musk shrew (Suncus murinus). Cell Calcium 2019; 80:175-188. [DOI: 10.1016/j.ceca.2019.05.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 04/23/2019] [Accepted: 05/08/2019] [Indexed: 12/17/2022]
|
5
|
Cipriani G, Gibbons SJ, Arumugam SS, Malysz J, Sha L, Szurszewski JH, Linden DR, Evangelista S, Faussone-Pellegrini MS, Vannucchi MG, Farrugia G. Changes in nitrergic and tachykininergic pathways in rat proximal colon in response to chronic treatment with otilonium bromide. Neurogastroenterol Motil 2015; 27:997-1009. [PMID: 25930994 PMCID: PMC4478139 DOI: 10.1111/nmo.12576] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 03/30/2015] [Indexed: 12/20/2022]
Abstract
BACKGROUND Otilonium bromide (OB) is used as a spasmolytic drug in the treatment of the functional bowel disorder irritable bowel syndrome. Although its acute effects on colonic relaxation are well-characterized, little is known about the effects of chronic administration of OB on enteric neurons, neuromuscular transmission, and interstitial cells of Cajal (ICC), key regulators of the gut function. METHODS Adult Sprague-Dawley rats were treated with OB in drinking water at a dose of 2 mg/kg for 30 days. The colons of OB-treated and age-matched control rats were studied by confocal immunohistochemistry to detect immunoreactivity (IR) in myenteric plexus neurons for nitrergic and tachykininergic markers, and also by microelectrode electrophysiology. KEY RESULTS Using immunohistochemistry, chronic OB administration did not change total neuron number, assessed by anti-Hu IR, but resulted in a significant increase in NK1 receptor positive neurons, a decrease in neuronal nitric oxide synthase expressing neurons, and a reduction in volume of substance P in nerve fibers in the myenteric plexus. Chronic OB administration potentiated inhibitory and excitatory junction potentials evoked by repetitive electrical field stimulation. The various types of colonic ICC, detected by Kit IR, were not altered nor were slow waves or smooth muscle membrane potential. CONCLUSIONS & INFERENCES Chronic treatment with OB caused significant changes in the nitrergic and tachykinergic components of the myenteric plexus and in both inhibitory and excitatory neurotransmission in the rat colon.
Collapse
Affiliation(s)
- Gianluca Cipriani
- Enteric NeuroScience Program, Division of Gastroenterology and Hepatology, Mayo Clinic Rochester, Rochester, MN, USA
| | - Simon J. Gibbons
- Enteric NeuroScience Program, Division of Gastroenterology and Hepatology, Mayo Clinic Rochester, Rochester, MN, USA
| | - Saravanaperumal Siva Arumugam
- Enteric NeuroScience Program, Division of Gastroenterology and Hepatology, Mayo Clinic Rochester, Rochester, MN, USA
| | - John Malysz
- Enteric NeuroScience Program, Division of Gastroenterology and Hepatology, Mayo Clinic Rochester, Rochester, MN, USA
| | - Lei Sha
- Enteric NeuroScience Program, Division of Gastroenterology and Hepatology, Mayo Clinic Rochester, Rochester, MN, USA
| | - Joseph H. Szurszewski
- Enteric NeuroScience Program, Division of Gastroenterology and Hepatology, Mayo Clinic Rochester, Rochester, MN, USA
| | - David R. Linden
- Enteric NeuroScience Program, Division of Gastroenterology and Hepatology, Mayo Clinic Rochester, Rochester, MN, USA
| | | | | | - Maria Giuliana Vannucchi
- Dept. Experimental and Clinical Medicine, Histology and Embryology Research Unit, Florence, Italy
| | - Gianrico Farrugia
- Enteric NeuroScience Program, Division of Gastroenterology and Hepatology, Mayo Clinic Rochester, Rochester, MN, USA
| |
Collapse
|
6
|
Drumm BT, Sergeant GP, Hollywood MA, Thornbury KT, Matsuda TT, Baba A, Harvey BJ, McHale NG. The effect of high [K(+)]o on spontaneous Ca(2+) waves in freshly isolated interstitial cells of Cajal from the rabbit urethra. Physiol Rep 2014; 2:e00203. [PMID: 24744882 PMCID: PMC3967686 DOI: 10.1002/phy2.203] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 12/19/2013] [Accepted: 12/23/2013] [Indexed: 11/20/2022] Open
Abstract
Interstitial cells of Cajal (ICC) act as putative pacemaker cells in the rabbit urethra. Pacemaker activity in ICC results from spontaneous global Ca2+ waves that can be increased in frequency by raising external [K+]. The purpose of this study was to elucidate the mechanism of this response. Intracellular [Ca2+] was measured in fluo‐4‐loaded smooth muscle cells (SMCs) and ICC using a Nipkow spinning disk confocal microscope. Increasing [K+]o to 60 mmol/L caused an increase in [Ca2+]i accompanied by contraction in SMCs. Raising [K+]o did not cause contraction in ICC, but the frequency of firing of spontaneous calcium waves increased. Reducing [Ca2+]o to 0 mmol/L abolished the response in both cell types. Nifedipine of 1 μmol/L blocked the response of SMC to high [K+]o, but did not affect the increase in firing in ICC. This latter effect was blocked by 30 μmol/L NiCl2 but not by the T‐type Ca2+ channel blocker mibefradil (300 nmol/L). However, inhibition of Ca2+ influx via reverse‐mode sodium/calcium exchange (NCX) using either 1 μmol/L SEA0400 or 5 μmol/L KB‐R7943 did block the effect of high [K+]o on ICC. These data suggest that high K+ solution increases the frequency of calcium waves in ICC by increasing Ca2+ influx through reverse‐mode NCX. Pacemaker activity in ICC results from spontaneous global Ca2+ waves that can be increased in frequency by raising external [K+]. The experiments described support the hypothesis that high K+ solution increases the frequency of calcium waves in ICC by increasing Ca2+ influx through reverse‐mode NCX.
Collapse
Affiliation(s)
- Bernard T Drumm
- Smooth Muscle Research Centre, Dundalk Institute of Technology, DundalkCo. Louth, Ireland ; Department of Molecular Medicine, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin 9, Ireland
| | - Gerard P Sergeant
- Smooth Muscle Research Centre, Dundalk Institute of Technology, DundalkCo. Louth, Ireland
| | - Mark A Hollywood
- Smooth Muscle Research Centre, Dundalk Institute of Technology, DundalkCo. Louth, Ireland
| | - Keith T Thornbury
- Smooth Muscle Research Centre, Dundalk Institute of Technology, DundalkCo. Louth, Ireland
| | - Toshio T Matsuda
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
| | - Akemichi Baba
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
| | - Brian J Harvey
- Department of Molecular Medicine, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin 9, Ireland
| | - Noel G McHale
- Smooth Muscle Research Centre, Dundalk Institute of Technology, DundalkCo. Louth, Ireland
| |
Collapse
|
7
|
Abstract
The tunica muscularis of the gastrointestinal (GI) tract contains two layers of smooth muscle cells (SMC) oriented perpendicular to each other. SMC express a variety of voltage-dependent and voltage-independent ionic conductance(s) that develop membrane potential and control excitability. Resting membrane potentials (RMP) vary through the GI tract but generally are within the range of -80 to -40 mV. RMP sets the 'gain' of smooth muscle and regulates openings of voltage-dependent Ca(2+) channels. A variety of K(+) channels contribute to setting RMP of SMC. In most regions, RMP is considerably less negative than the K(+) equilibrium potential, due to a finely tuned balance between background K(+) channels and non-selective cation channels (NSCC). Variations in expression patterns and openings of K(+) channels and NSCC account for differences of the RMP in different regions of the GI tract. Smooth muscle excitability is also regulated by interstitial cells (interstitial cells of Cajal (ICC) and PDGFRα(+) cells) that express additional conductances and are electrically coupled to SMC. Thus, 'myogenic' activity results from the integrated behavior of the SMC/ICC/PDGFRα(+) cell (SIP) syncytium. Inputs from excitatory and inhibitory motor neurons are required to produce the complex motor patterns of the gut. Motor neurons innervate three cell types in the SIP, and receptors, second messenger pathways, and ion channels in these cells mediate postjunctional responses. Studies of isolated SIP cells have begun to unravel the mechanisms responsible for neural responses. This review discusses ion channels that set and regulate RMP of SIP cells and how neurotransmitters regulate membrane potential.
Collapse
Affiliation(s)
- Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89558, USA.
| | | | | |
Collapse
|
8
|
Beyder A, Farrugia G. Targeting ion channels for the treatment of gastrointestinal motility disorders. Therap Adv Gastroenterol 2012; 5:5-21. [PMID: 22282704 PMCID: PMC3263980 DOI: 10.1177/1756283x11415892] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Gastrointestinal (GI) functional and motility disorders are highly prevalent and responsible for long-term morbidity and sometimes mortality in the affected patients. It is estimated that one in three persons has a GI functional or motility disorder. However, diagnosis and treatment of these widespread conditions remains challenging. This partly stems from the multisystem pathophysiology, including processing abnormalities in the central and peripheral (enteric) nervous systems and motor dysfunction in the GI wall. Interstitial cells of Cajal (ICCs) are central to the generation and propagation of the cyclical electrical activity and smooth muscle cells (SMCs) are responsible for electromechanical coupling. In these and other excitable cells voltage-sensitive ion channels (VSICs) are the main molecular units that generate and regulate electrical activity. Thus, VSICs are potential targets for intervention in GI motility disorders. Research in this area has flourished with advances in the experimental methods in molecular and structural biology and electrophysiology. However, our understanding of the molecular mechanisms responsible for the complex and variable electrical behavior of ICCs and SMCs remains incomplete. In this review, we focus on the slow waves and action potentials in ICCs and SMCs. We describe the constituent VSICs, which include voltage-gated sodium (Na(V)), calcium (Ca(V)), potassium (K(V), K(Ca)), chloride (Cl(-)) and nonselective ion channels (transient receptor potentials [TRPs]). VSICs have significant structural homology and common functional mechanisms. We outline the approaches and limitations and provide examples of targeting VSICs at the pores, voltage sensors and alternatively spliced sites. Rational drug design can come from an integrated view of the structure and mechanisms of gating and activation by voltage or mechanical stress.
Collapse
Affiliation(s)
- Arthur Beyder
- Enteric Neuroscience Program, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, MN, USA
| | | |
Collapse
|
9
|
Lees-Green R, Du P, O'Grady G, Beyder A, Farrugia G, Pullan AJ. Biophysically based modeling of the interstitial cells of cajal: current status and future perspectives. Front Physiol 2011; 2:29. [PMID: 21772822 PMCID: PMC3131535 DOI: 10.3389/fphys.2011.00029] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 06/13/2011] [Indexed: 12/29/2022] Open
Abstract
Gastrointestinal motility research is progressing rapidly, leading to significant advances in the last 15 years in understanding the cellular mechanisms underlying motility, following the discovery of the central role played by the interstitial cells of Cajal (ICC). As experimental knowledge of ICC physiology has expanded, biophysically based modeling has become a valuable tool for integrating experimental data, for testing hypotheses on ICC pacemaker mechanisms, and for applications in in silico studies including in multiscale models. This review is focused on the cellular electrophysiology of ICC. Recent evidence from both experimental and modeling domains have called aspects of the existing pacemaker theories into question. Therefore, current experimental knowledge of ICC pacemaker mechanisms is examined in depth, and current theories of ICC pacemaking are evaluated and further developed. Existing biophysically based ICC models and their physiological foundations are then critiqued in light of the recent advances in experimental knowledge, and opportunities to improve these models are identified. The review concludes by examining several potential clinical applications of biophysically based ICC modeling from the subcellular through to the organ level, including ion channelopathies and ICC network degradation.
Collapse
Affiliation(s)
- Rachel Lees-Green
- Auckland Bioengineering Institute, The University of Auckland Auckland, New Zealand
| | | | | | | | | | | |
Collapse
|
10
|
Kodama Y, Iino S, Shigemasa Y, Suzuki H. Properties of acetylcholine-induced relaxation of smooth muscle isolated from the proximal colon of the guinea-pig. J Smooth Muscle Res 2011; 46:185-200. [PMID: 20859066 DOI: 10.1540/jsmr.46.185] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The properties of mechanical responses elicited by stimulation with acetylcholine (ACh) were investigated in circular smooth muscle preparations isolated from the proximal colon of guinea-pig. Application of ACh (10(-8)-10(-6) M) for 3-5 min produced a biphasic response, with an initial contraction followed by a relaxation. Atropine inhibited the initial contraction, while N(ω)-nitro-L-arginine (L-NA) inhibited the relaxation, suggesting that the former was produced by activation of muscarinic receptors while the latter was produced by an elevated production of nitric oxide (NO). In the presence of atropine, the ACh-relaxation was attenuated by removal of the mucosa and abolished by removal of both submucosal and mucosal layers. The ACh-induced relaxation was also attenuated by either tetrodotoxin (TTX, 3 × 10(-7) M) or hexamethonium (10(-6) M). In the presence of atropine, transmural nerve stimulation (TNS) elicited a biphasic response, with an initial phasic contraction followed by a relaxation. The amplitude of TNS-induced relaxation was significantly reduced by hexamethonium or L-NA and was abolished by TTX. Both ACh and TNS produced relaxation in preparations isolated from the proximal colon, but not in those from the middle part of colon. Immunohistochemistry for neuronal nitric oxide synthase revealed no difference in the distribution of nitrergic nerves between the proximal and middle part of the colon, with nitrergic nerves in both the mucosal and submucosal layers as well as in the smooth muscle and myenteric layers. These results suggest that ACh induces NO production by excitation of postganglionic nerves distributed mainly in the mucosal and submucosal layers. In circular smooth muscle preparations isolated from the middle part of colon, ACh or TNS produced contractile responses alone, with no associated relaxation, suggesting that the ACh-activated postganglionic nitrergic nerves are distributed in the mucosal and submucosal layers of the proximal colon but not in the middle part of the colon.
Collapse
Affiliation(s)
- Youhei Kodama
- Department of Cell Physiology, Nagoya City University Medical School, Mizuho-ku, Japan
| | | | | | | |
Collapse
|
11
|
Takaki M, Suzuki H, Nakayama S. Recent advances in studies of spontaneous activity in smooth muscle: ubiquitous pacemaker cells. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2010; 102:129-35. [PMID: 20553741 DOI: 10.1016/j.pbiomolbio.2010.05.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Accepted: 05/19/2010] [Indexed: 02/08/2023]
Abstract
The general and specific properties of pacemaker cells, including Kit-negative cells, that are distributed in gastrointestinal, urethral and uterine smooth muscle tissues, are discussed herein. In intestinal tissues, interstitial cells of Cajal (ICC) are heterogeneous in both their forms and roles. ICC distributed in the myenteric layer (ICC-MY) act as primary pacemaker cells for intestinal mechanical and electrical activity. ICC distributed in muscle bundles play a role as mediators of signals from autonomic nerves to smooth muscle cells. A group of ICC also appears to act as a stretch sensor. Intracellular Ca2+ dynamics play a crucial role in ICC-MY pacemaking; intracellular Ca2+ ([Ca2+](i)) oscillations periodically activate plasmalemmal Ca2+-activated ion channels, such as Ca2+-activated Cl(-) channels and/or non-selective cation channels, although the relative contributions of these channels are not defined. With respect to gut motility, both the ICC network and enteric nervous system, including excitatory and inhibitory enteric neurons, play an essential role in producing highly coordinated peristalsis.
Collapse
Affiliation(s)
- Miyako Takaki
- Department of Physiology II, Nara Medical University, 840 Shijo-cho, Kashihara 634-8521, Japan.
| | | | | |
Collapse
|
12
|
Fujimoto H, Shigemasa Y, Suzuki H. Properties of spontaneous contractions and their modulation by transmural nerve stimulation in circular smooth muscle isolated from the pacemaker area in the flexure region of the guinea-pig colon. J Smooth Muscle Res 2010; 46:293-308. [DOI: 10.1540/jsmr.46.293] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Hiroyuki Fujimoto
- Department of Cell Physiology, Nagoya City University Medical School
| | - Yuhsuke Shigemasa
- Department of Cell Physiology, Nagoya City University Medical School
| | - Hikaru Suzuki
- Department of Cell Physiology, Nagoya City University Medical School
| |
Collapse
|
13
|
Gibbons SJ, Strege PR, Lei S, Roeder JL, Mazzone A, Ou Y, Rich A, Farrugia G. The alpha1H Ca2+ channel subunit is expressed in mouse jejunal interstitial cells of Cajal and myocytes. J Cell Mol Med 2008; 13:4422-31. [PMID: 19413888 PMCID: PMC2855776 DOI: 10.1111/j.1582-4934.2008.00623.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
T-type Ca2+ currents have been detected in cells from the external muscular layers of gastrointestinal smooth muscles and appear to contribute to the generation of pacemaker potentials in interstitial cells of Cajal from those tissues. However, the Ca2+ channel α subunit responsible for these currents has not been determined. We established that the α subunit of the α1H Ca2+ channel is expressed in single myocytes and interstitial cells of Cajal using reverse transcription and polymerase chain reaction from whole tissue, laser capture microdissected tissue and single cells isolated from the mouse jejunum. Whole-cell voltage clamp recordings demonstrated that a nifedipine and Cd2+ resistant, mibefradil-sensitive current is present in myocytes dissociated from the jejunum. Electrical recordings from the circular muscle layer demonstrated that mibefradil reduced the frequency and initial rate of rise of the electrical slow wave. Gene targeted knockout of both alleles of the cacna1h gene, which encodes the α1H Ca2+ channel subunit, resulted in embryonic lethality because of death of the homozygous knockouts prior to E13.5 days in utero. We conclude that a channel with the pharmacological and molecular characteristics of the α1H Ca2+ channel subunit is expressed in interstitial cells of Cajal and myocytes from the mouse jejunum, and that ionic conductances through the α1H Ca2+ channel contribute to the upstroke of the pacemaker potential. Furthermore, the survival of mice that do not express the α1H Ca2+ channel protein is dependent on the genetic background and targeting approach used to generate the knockout mice.
Collapse
Affiliation(s)
- Simon J Gibbons
- Enteric Neuroscience Program, Mayo Clinic College of Medicine, Rochester, MN, USA.
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Nakayama S, Kajioka S, Goto K, Takaki M, Liu HN. Calcium-associated mechanisms in gut pacemaker activity. J Cell Mol Med 2008; 11:958-68. [PMID: 17979877 PMCID: PMC4401267 DOI: 10.1111/j.1582-4934.2007.00107.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
A considerable body of evidence has revealed that interstitial cells of Cajal (ICC), identified with c-Kit-immunoreactivity, act as gut pacemaker cells, with spontaneous Ca2+ activity in ICC as the probable primary mechanism. Namely, intracellular (cytosolic) Ca2+ oscillations in ICC periodically activate plasmalemmal Ca2+-dependent ion channels and thereby generate pacemaker potentials. This review will, thus, focus on Ca2+-associated mechanisms in ICC in the gastrointestinal (GI) tract, including auxiliary organs.
Collapse
Affiliation(s)
- Shinsuke Nakayama
- Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
| | | | | | | | | |
Collapse
|