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Sanders KM, Drumm BT, Cobine CA, Baker SA. Ca 2+ dynamics in interstitial cells: foundational mechanisms for the motor patterns in the gastrointestinal tract. Physiol Rev 2024; 104:329-398. [PMID: 37561138 DOI: 10.1152/physrev.00036.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 06/29/2023] [Accepted: 08/06/2023] [Indexed: 08/11/2023] Open
Abstract
The gastrointestinal (GI) tract displays multiple motor patterns that move nutrients and wastes through the body. Smooth muscle cells (SMCs) provide the forces necessary for GI motility, but interstitial cells, electrically coupled to SMCs, tune SMC excitability, transduce inputs from enteric motor neurons, and generate pacemaker activity that underlies major motor patterns, such as peristalsis and segmentation. The interstitial cells regulating SMCs are interstitial cells of Cajal (ICC) and PDGF receptor (PDGFR)α+ cells. Together these cells form the SIP syncytium. ICC and PDGFRα+ cells express signature Ca2+-dependent conductances: ICC express Ca2+-activated Cl- channels, encoded by Ano1, that generate inward current, and PDGFRα+ cells express Ca2+-activated K+ channels, encoded by Kcnn3, that generate outward current. The open probabilities of interstitial cell conductances are controlled by Ca2+ release from the endoplasmic reticulum. The resulting Ca2+ transients occur spontaneously in a stochastic manner. Ca2+ transients in ICC induce spontaneous transient inward currents and spontaneous transient depolarizations (STDs). Neurotransmission increases or decreases Ca2+ transients, and the resulting depolarizing or hyperpolarizing responses conduct to other cells in the SIP syncytium. In pacemaker ICC, STDs activate voltage-dependent Ca2+ influx, which initiates a cluster of Ca2+ transients and sustains activation of ANO1 channels and depolarization during slow waves. Regulation of GI motility has traditionally been described as neurogenic and myogenic. Recent advances in understanding Ca2+ handling mechanisms in interstitial cells and how these mechanisms influence motor patterns of the GI tract suggest that the term "myogenic" should be replaced by the term "SIPgenic," as this review discusses.
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Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada-Reno, Reno, Nevada, United States
| | - Bernard T Drumm
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Caroline A Cobine
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Salah A Baker
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada-Reno, Reno, Nevada, United States
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Drumm BT, Thornbury KD, Hollywood MA, Sergeant GP. Role of Ano1 Ca 2+-activated Cl - channels in generating urethral tone. Am J Physiol Renal Physiol 2021; 320:F525-F536. [PMID: 33554780 DOI: 10.1152/ajprenal.00520.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Urinary continence is maintained in the lower urinary tract by the contracture of urethral sphincters, including smooth muscle of the internal urethral sphincter. These contractions occlude the urethral lumen, preventing urine leakage from the bladder to the exterior. Over the past 20 years, research on the ionic conductances that contribute to urethral smooth muscle contractility has greatly accelerated. A debate has emerged over the role of interstitial cell of Cajal (ICC)-like cells in the urethra and their expression of Ca2+-activated Cl- channels encoded by anoctamin-1 [Ano1; transmembrane member 16 A (Tmem16a) gene]. It has been proposed that Ano1 channels expressed in urethral ICC serve as a source of depolarization for smooth muscle cells, increasing their excitability and contributing to tone. Although a clear role for Ano1 channels expressed in ICC is evident in other smooth muscle organs, such as the gastrointestinal tract, the role of these channels in the urethra is unclear, owing to differences in the species (rabbit, rat, guinea pig, sheep, and mouse) examined and experimental approaches by different groups. The importance of clarifying this situation is evident as effective targeting of Ano1 channels may lead to new treatments for urinary incontinence. In this review, we summarize the key findings from different species on the role of ICC and Ano1 channels in urethral contractility. Finally, we outline proposals for clarifying this controversial and important topic by addressing how cell-specific optogenetic and inducible cell-specific genetic deletion strategies coupled with advances in Ano1 channel pharmacology may clarify this area in future studies.NEW & NOTEWORTHY Studies from the rabbit have shown that anoctamin-1 (Ano1) channels expressed in urethral interstitial cells of Cajal (ICC) serve as a source of depolarization for smooth muscle cells, increasing excitability and tone. However, the role of urethral Ano1 channels is unclear, owing to differences in the species examined and experimental approaches. We summarize findings from different species on the role of urethral ICC and Ano1 channels in urethral contractility and outline proposals for clarifying this topic using cell-specific optogenetic approaches.
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Affiliation(s)
- Bernard T Drumm
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Keith D Thornbury
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Mark A Hollywood
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Gerard P Sergeant
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
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Chen D, Meng W, Shu L, Liu S, Gu Y, Wang X, Feng M. ANO1 in urethral SMCs contributes to sex differences in urethral spontaneous tone. Am J Physiol Renal Physiol 2020; 319:F394-F402. [PMID: 32686521 DOI: 10.1152/ajprenal.00174.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Stress urinary incontinence (SUI) is more common in women than in men, and sex differences in anatomic structure and physiology have been suggested as causes; however, the underlying cellular and molecular mechanisms remain unclear. The spontaneous tone (STT) of the urethra has been shown to have a fundamental effect on preventing the occurrence of SUI. Here, we investigated whether the urethral STT exhibited sex differences. First, we isolated urethral smooth muscle (USM) and detected STT in female mice and women. No STT was found in male mice or men. Furthermore, caffeine induced increased contractility and intracellular Ca2+ concentration in urethrae from female mice compared with male mice. EACT [an N-aroylaminothiazole, anoctamin-1 (ANO1) activator] elicited increased intracellular Ca2+ concentration and stronger currents in female mice than in male mice. Moreover, ANO1 expression in single USM cells from women and female mice was almost twofold higher than that found in cells from men and male mice. In summary, ANO1 in USM contributes to sex differences in urethral spontaneous tone. This finding may provide new guidance for the treatment of SUI in women and men.
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Affiliation(s)
- Defang Chen
- Department of Outpatient, Central Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Wen Meng
- Pharmacy Intravenous Admixture Services, Central Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Ling Shu
- Operating Room, Central Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Shuang Liu
- Central Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Yongzhong Gu
- Department of Obstetrics and Gynecology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Xiaoyan Wang
- General Practice Department, College of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Mei Feng
- Central Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China,Central Laboratory, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
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Shoda W, Nomura N, Ando F, Tagashira H, Iwamoto T, Ohta A, Isobe K, Mori T, Susa K, Sohara E, Rai T, Uchida S. Sodium-calcium exchanger 1 is the key molecule for urinary potassium excretion against acute hyperkalemia. PLoS One 2020; 15:e0235360. [PMID: 32603346 PMCID: PMC7326190 DOI: 10.1371/journal.pone.0235360] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 06/13/2020] [Indexed: 02/07/2023] Open
Abstract
The sodium (Na+)-chloride cotransporter (NCC) expressed in the distal convoluted tubule (DCT) is a key molecule regulating urinary Na+ and potassium (K+) excretion. We previously reported that high-K+ load rapidly dephosphorylated NCC and promoted urinary K+ excretion in mouse kidneys. This effect was inhibited by calcineurin (CaN) and calmodulin inhibitors. However, the detailed mechanism through which high-K+ signal results in CaN activation remains unknown. We used Flp-In NCC HEK293 cells and mice to evaluate NCC phosphorylation. We analyzed intracellular Ca2+ concentration ([Ca2+]in) using live cell Ca2+ imaging in HEK293 cells. We confirmed that high-K+-induced NCC dephosphorylation was not observed without CaN using Flp-In NCC HEK29 cells. Extracellular Ca2+ reduction with a Ca2+ chelator inhibited high-K+-induced increase in [Ca2+]in and NCC dephosphorylation. We focused on Na+/Ca2+ exchanger (NCX) 1, a bidirectional regulator of cytosolic Ca2+ expressed in DCT. We identified that NCX1 suppression with a specific inhibitor (SEA0400) or siRNA knockdown inhibited K+-induced increase in [Ca2+]in and NCC dephosphorylation. In a mouse study, SEA0400 treatment inhibited K+-induced NCC dephosphorylation. SEA0400 reduced urinary K+ excretion and induced hyperkalemia. Here, we identified NCX1 as a key molecule in urinary K+ excretion promoted by CaN activation and NCC dephosphorylation in response to K+ load.
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Affiliation(s)
- Wakana Shoda
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Naohiro Nomura
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
- * E-mail:
| | - Fumiaki Ando
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Hideaki Tagashira
- Department of pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Takahiro Iwamoto
- Department of pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Akihito Ohta
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Kiyoshi Isobe
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Takayasu Mori
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Koichiro Susa
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Eisei Sohara
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Tatemitsu Rai
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Shinichi Uchida
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
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Rembetski BE, Sanders KM, Drumm BT. Contribution of Ca v1.2 Ca 2+ channels and store-operated Ca 2+ entry to pig urethral smooth muscle contraction. Am J Physiol Renal Physiol 2020; 318:F496-F505. [PMID: 31904286 DOI: 10.1152/ajprenal.00514.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Urethral smooth muscle (USM) generates tone to prevent urine leakage from the bladder during filling. USM tone has been thought to be a voltage-dependent process, relying on Ca2+ influx via voltage-dependent Ca2+ channels in USM cells, modulated by the activation of Ca2+-activated Cl- channels encoded by Ano1. However, recent findings in the mouse have suggested that USM tone is voltage independent, relying on Ca2+ influx through Orai channels via store-operated Ca2+ entry (SOCE). We explored if this pathway also occurred in the pig using isometric tension recordings of USM tone. Pig USM strips generated myogenic tone, which was nearly abolished by the Cav1.2 channel antagonist nifedipine and the ATP-dependent K+ channel agonist pinacidil. Pig USM tone was reduced by the Orai channel blocker GSK-7975A. Electrical field stimulation (EFS) led to phentolamine-sensitive contractions of USM strips. Contractions of pig USM were also induced by phenylephrine. Phenylephrine-evoked and EFS-evoked contractions of pig USM were reduced by ~50-75% by nifedipine and ~30% by GSK-7975A. Inhibition of Ano1 channels had no effect on tone or EFS-evoked contractions of pig USM. In conclusion, unlike the mouse, pig USM exhibited voltage-dependent tone and agonist/EFS-evoked contractions. Whereas SOCE plays a role in generating tone and agonist/neural-evoked contractions in both species, this dominates in the mouse. Tone and agonist/EFS-evoked contractions of pig USM are the result of Ca2+ influx primarily through Cav1.2 channels, and no evidence was found supporting a role of Ano1 channels in modulating these mechanisms.
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Affiliation(s)
- Benjamin E Rembetski
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno Nevada
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno Nevada
| | - Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno Nevada
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Drumm BT, Hennig GW, Baker SA, Sanders KM. Applications of Spatio-temporal Mapping and Particle Analysis Techniques to Quantify Intracellular Ca2+ Signaling In Situ. J Vis Exp 2019. [PMID: 30663707 DOI: 10.3791/58989] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Ca2+ imaging of isolated cells or specific types of cells within intact tissues often reveals complex patterns of Ca2+ signaling. This activity requires careful and in-depth analyses and quantification to capture as much information about the underlying events as possible. Spatial, temporal and intensity parameters intrinsic to Ca2+ signals such as frequency, duration, propagation, velocity and amplitude may provide some biological information required for intracellular signalling. High-resolution Ca2+ imaging typically results in the acquisition of large data files that are time consuming to process in terms of translating the imaging information into quantifiable data, and this process can be susceptible to human error and bias. Analysis of Ca2+ signals from cells in situ typically relies on simple intensity measurements from arbitrarily selected regions of interest (ROI) within a field of view (FOV). This approach ignores much of the important signaling information contained in the FOV. Thus, in order to maximize recovery of information from such high-resolution recordings obtained with Ca2+dyes or optogenetic Ca2+ imaging, appropriate spatial and temporal analysis of the Ca2+ signals is required. The protocols outlined in this paper will describe how a high volume of data can be obtained from Ca2+ imaging recordings to facilitate more complete analysis and quantification of Ca2+ signals recorded from cells using a combination of spatiotemporal map (STM)-based analysis and particle-based analysis. The protocols also describe how different patterns of Ca2+ signaling observed in different cell populations in situ can be analyzed appropriately. For illustration, the method will examine Ca2+ signaling in a specialized population of cells in the small intestine, interstitial cells of Cajal (ICC), using GECIs.
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Affiliation(s)
- Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine;
| | - Grant W Hennig
- Department of Pharmacology, The Robert Larner, M.D. College of Medicine, University of Vermont
| | - Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine
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Sergeant GP, Hollywood MA, Thornbury KD. Spontaneous Activity in Urethral Smooth Muscle. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1124:149-167. [DOI: 10.1007/978-981-13-5895-1_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Rembetski BE, Cobine CA, Drumm BT. Laboratory practical to study the differential innervation pathways of urinary tract smooth muscle. ADVANCES IN PHYSIOLOGY EDUCATION 2018; 42:295-304. [PMID: 29676616 PMCID: PMC7474251 DOI: 10.1152/advan.00014.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 02/26/2018] [Accepted: 03/13/2018] [Indexed: 06/08/2023]
Abstract
In the mammalian lower urinary tract, there is a reciprocal relationship between the contractile state of the bladder and urethra. As the bladder fills with urine, it remains relaxed to accommodate increases in volume, while the urethra remains contracted to prevent leakage of urine from the bladder to the exterior. Disruptions to the normal contractile state of the bladder and urethra can lead to abnormal micturition patterns and urinary incontinence. While both the bladder and urethra are smooth-muscle organs, they are differentially contracted by input from cholinergic and sympathetic nerves, respectively. The laboratory practical described here provides an experiential approach to understanding the anatomy of the lower urinary tract. Several key factors in urinary tract physiology are outlined, e.g., the bladder is contracted by activation of the parasympathetic pathway via cholinergic stimulation on muscarinic receptors, whereas the urethra is contracted by activation of the sympathetic pathway via adrenergic stimulation on α1-adrenoceptors. This is achieved by measuring the force generated by bladder and urethra smooth muscle to demonstrate that acetylcholine contracts the smooth muscle of the bladder, whereas adrenergic agonists contract the urethral smooth muscle. An inhibition of these effects is also demonstrated by application of the muscarinic receptor antagonist atropine and the α1-adrenergic receptor blocker phentolamine. A list of suggested techniques and exam questions to evaluate student understanding on this topic is also provided.
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Affiliation(s)
- Benjamin E Rembetski
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine , Reno, Nevada
| | - Caroline A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine , Reno, Nevada
| | - Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine , Reno, Nevada
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Drumm BT, Rembetski BE, Cobine CA, Baker SA, Sergeant GP, Hollywood MA, Thornbury KD, Sanders KM. Ca 2+ signalling in mouse urethral smooth muscle in situ: role of Ca 2+ stores and Ca 2+ influx mechanisms. J Physiol 2018; 596:1433-1466. [PMID: 29383731 PMCID: PMC5899989 DOI: 10.1113/jp275719] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 01/17/2018] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Contraction of urethral smooth muscle cells (USMCs) contributes to urinary continence. Ca2+ signalling in USMCs was investigated in intact urethral muscles using a genetically encoded Ca2+ sensor, GCaMP3, expressed selectively in USMCs. USMCs were spontaneously active in situ, firing intracellular Ca2+ waves that were asynchronous at different sites within cells and between adjacent cells. Spontaneous Ca2+ waves in USMCs were myogenic but enhanced by adrenergic or purinergic agonists and decreased by nitric oxide. Ca2+ waves arose from inositol trisphosphate type 1 receptors and ryanodine receptors, and Ca2+ influx by store-operated calcium entry was required to maintain Ca2+ release events. Ca2+ release and development of Ca2+ waves appear to be the primary source of Ca2+ for excitation-contraction coupling in the mouse urethra, and no evidence was found that voltage-dependent Ca2+ entry via L-type or T-type channels was required for responses to α adrenergic responses. ABSTRACT Urethral smooth muscle cells (USMCs) generate myogenic tone and contribute to urinary continence. Currently, little is known about Ca2+ signalling in USMCs in situ, and therefore little is known about the source(s) of Ca2+ required for excitation-contraction coupling. We characterized Ca2+ signalling in USMCs within intact urethral muscles using a genetically encoded Ca2+ sensor, GCaMP3, expressed selectively in USMCs. USMCs fired spontaneous intracellular Ca2+ waves that did not propagate cell-to-cell across muscle bundles. Ca2+ waves increased dramatically in response to the α1 adrenoceptor agonist phenylephrine (10 μm) and to ATP (10 μm). Ca2+ waves were inhibited by the nitric oxide donor DEA NONOate (10 μm). Ca2+ influx and release from sarcoplasmic reticulum stores contributed to Ca2+ waves, as Ca2+ free bathing solution and blocking the sarcoplasmic Ca2+ -ATPase abolished activity. Intracellular Ca2+ release involved cooperation between ryanadine receptors and inositol trisphosphate receptors, as tetracaine and ryanodine (100 μm) and xestospongin C (1 μm) reduced Ca2+ waves. Ca2+ waves were insensitive to L-type Ca2+ channel modulators nifedipine (1 μm), nicardipine (1 μm), isradipine (1 μm) and FPL 64176 (1 μm), and were unaffected by the T-type Ca2+ channel antagonists NNC-550396 (1 μm) and TTA-A2 (1 μm). Ca2+ waves were reduced by the store operated Ca2+ entry blocker SKF 96365 (10 μm) and by an Orai antagonist, GSK-7975A (1 μm). The latter also reduced urethral contractions induced by phenylephrine, suggesting that Orai can function effectively as a receptor-operated channel. In conclusion, Ca2+ waves in mouse USMCs are a source of Ca2+ for excitation-contraction coupling in urethral muscles.
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Affiliation(s)
- Bernard T. Drumm
- Department of Physiology and Cell BiologyUniversity of Nevada, Reno School of MedicineRenoNV89557USA
| | - Benjamin E. Rembetski
- Department of Physiology and Cell BiologyUniversity of Nevada, Reno School of MedicineRenoNV89557USA
| | - Caroline A. Cobine
- Department of Physiology and Cell BiologyUniversity of Nevada, Reno School of MedicineRenoNV89557USA
| | - Salah A. Baker
- Department of Physiology and Cell BiologyUniversity of Nevada, Reno School of MedicineRenoNV89557USA
| | - Gerard P. Sergeant
- Smooth Muscle Research CentreDundalk Institute of TechnologyCo. LouthDundalkRepublic of Ireland
| | - Mark A. Hollywood
- Smooth Muscle Research CentreDundalk Institute of TechnologyCo. LouthDundalkRepublic of Ireland
| | - Keith D. Thornbury
- Smooth Muscle Research CentreDundalk Institute of TechnologyCo. LouthDundalkRepublic of Ireland
| | - Kenton M. Sanders
- Department of Physiology and Cell BiologyUniversity of Nevada, Reno School of MedicineRenoNV89557USA
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Guo T, Li J, Li J, Kong D, Bi C, He Z, Tang D, Jin X, Jin L. Association between hyperpolarization-activated channel in interstitial cells of Cajal and gastrointestinal dysmotility induced by malignant ascites. Oncol Lett 2017; 13:1601-1608. [PMID: 28454297 PMCID: PMC5403200 DOI: 10.3892/ol.2017.5652] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 11/03/2016] [Indexed: 12/20/2022] Open
Abstract
Advanced malignant ascites is accompanied by gastrointestinal dysmotility, and patients often feel abdominal pain, abdominal distention, nausea and constipation. Gastrointestinal dysmotility is not only painful for the patients, but it reduces the absorption of nutrients and affects the physical recovery of patients with malignant ascites. It is reported that changes in interstitial cells of Cajal (ICCs) are responsible for the gastrointestinal dysmotility induced by malignant ascites, but the mechanism is not completely understood. The present study observed a significantly decreased expression of ion channels, including hyperpolarization-activated cyclic nucleotide-gated potassium channel 2 (HCN2) and cyclic adenosine monophosphate, in the condition of malignant ascites. Using electrophysiology, it was identified that malignant ascites led to lower amplitude and slower frequency signals in cells of the small intestine. In addition, when ICCs were cultured with malignant ascites in vitro, the expression of HCN2 of ICCs was significantly reduced, and the data of flow cytometry revealed that the Ca2+ concentration of ICCs was also decreased. The results of electron microscopy analysis demonstrated the nuclei of ICCs were pyknotic, and the processes of ICCs were reduced in malignant ascites. The present study suggests the small intestinal dysmotility caused by malignant ascites may be associated with changes in HCN2 of ICCs, which offers a potential therapeutic target for gastrointestinal dysmotility in advanced malignant ascites.
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Affiliation(s)
- Tieyun Guo
- Department of Histology and Embryology, Basic Medical Science College, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Jiade Li
- Department of Pathology, Basic Medical Science College, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Jing Li
- Department of Pathology, Basic Medical Science College, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Dan Kong
- Department of Gynecology, The Third Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Chunli Bi
- Department of Pathology, Basic Medical Science College, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Zheng He
- Department of Pathology, Basic Medical Science College, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Dai Tang
- Department of Pathology, Basic Medical Science College, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Xiaoming Jin
- Department of Pathology, Basic Medical Science College, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Lianhong Jin
- Department of Histology and Embryology, Basic Medical Science College, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
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Drumm BT, Large RJ, Hollywood MA, Thornbury KD, Baker SA, Harvey BJ, McHale NG, Sergeant GP. The role of Ca(2+) influx in spontaneous Ca(2+) wave propagation in interstitial cells of Cajal from the rabbit urethra. J Physiol 2015; 593:3333-50. [PMID: 26046824 DOI: 10.1113/jp270883] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 06/01/2015] [Indexed: 12/25/2022] Open
Abstract
KEY POINTS Tonic contractions of rabbit urethra are associated with spontaneous electrical slow waves that are thought to originate in pacemaker cells termed interstitial cells of Cajal (ICC). ICC pacemaker activity results from their ability to generate propagating Ca(2+) waves, although the exact mechanisms of propagation are not understood. In this study, we have identified spontaneous localised Ca(2+) events for the first time in urethral ICC; these were due to Ca(2+) release from the endoplasmic reticulum (ER) via ryanodine receptors (RyRs) and, while they often remained localised, they sometimes initiated propagating Ca(2+) waves. We show that propagation of Ca(2+) waves in urethral ICC is critically dependent upon Ca(2+) influx via reverse mode NCX. Our data provide a clearer understanding of the intracellular mechanisms involved in the generation of ICC pacemaker activity. Interstitial cells of Cajal (ICC) are putative pacemaker cells in the rabbit urethra. Pacemaker activity in ICC results from spontaneous propagating Ca(2+) waves that are modulated by [Ca(2+)]o and whose propagation is inhibited by inositol tri-phosphate receptor (IP3 R) blockers. The purpose of this study was to further examine the role of Ca(2+) influx and Ca(2+) release in the propagation of Ca(2+) waves. Intracellular Ca(2+) was measured in Fluo-4-loaded ICC using a Nipkow spinning disc confocal microscope at fast acquisition rates (50 fps). We identified previously undetected localised Ca(2+) events originating from ryanodine receptors (RyRs). Inhibiting Ca(2+) influx by removing [Ca(2+)]o or blocking reverse mode sodium-calcium exchange (NCX) with KB-R 7943 or SEA-0400 abolished Ca(2+) waves, while localised Ca(2+) events persisted. Stimulating RyRs with 1 mm caffeine restored propagation. Propagation was also inhibited when Ca(2+) release sites were uncoupled by buffering intracellular Ca(2+) with EGTA-AM. This was reversed when Ca(2+) influx via NCX was increased by reducing [Na(+)]o to 13 mm. Low [Na(+)]o also increased the frequency of Ca(2+) waves and this effect was blocked by tetracaine and ryanodine but not 2-aminoethoxydiphenyl borate (2-APB). RT-PCR revealed that isolated ICC expressed both RyR2 and RyR3 subtypes. We conclude: (i) RyRs are required for the initiation of Ca(2+) waves, but wave propagation normally depends on activation of IP3 Rs; (ii) under resting conditions, propagation by IP3 Rs requires sensitisation by influx of Ca(2+) via reverse mode NCX; (iii) propagation can be maintained by RyRs if they have been sensitised to Ca(2+).
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Affiliation(s)
- Bernard T Drumm
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland.,Department of Molecular Medicine, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin 9, Ireland.,Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, 89557, USA
| | - Roddy J Large
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Mark A Hollywood
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Keith D Thornbury
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, 89557, USA
| | - 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, Dundalk, Co. Louth, Ireland
| | - Gerard P Sergeant
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
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Calcium signalling in Cajal-like interstitial cells of the lower urinary tract. Nat Rev Urol 2014; 11:555-64. [PMID: 25224445 DOI: 10.1038/nrurol.2014.241] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Interstitial cells of Cajal (ICC) serve several critical physiological roles in visceral smooth muscle organs, including acting as electrical pacemakers to modulate phasic contractile activity and as intermediaries in motor neurotransmission. The major roles of ICC have been described in the gastrointestinal tract, however, ICC-like cells (ICC-LC) can also be found in other visceral organs, including those of the lower urinary tract (LUT), where they provide similar functions, acting as electrical pacemakers and as intermediary cells involved in the modulation of neurotransmission to adjacent smooth muscle cells. The physiological functions of ICC-LC, in particular their role as pacemakers, relies on their ability to generate transient and propagating intracellular Ca(2+) events. The role of ICC-LC as pacemakers and neuromodulators in the LUT is increasingly apparent and the study of their intracellular Ca(2+) dynamics will provide a better understanding of their role in LUT excitability.
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