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Grainger N. Identifying peristaltic pacemaker cells in the upper urinary tract. J Physiol 2024. [PMID: 38180778 DOI: 10.1113/jp284754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Accepted: 12/18/2023] [Indexed: 01/06/2024] Open
Abstract
Urine expulsion from the upper urinary tract is a necessary process that eliminates waste, promotes renal filtration and prevents nephron damage. To facilitate the movement of urine boluses throughout the upper urinary tract, smooth muscle cells that line the renal pelvis contract in a coordinated effort to form peristaltic waves. Resident pacemaker cells in the renal pelvis are critical to this process and spontaneously evoke transient depolarizations that initiate each peristaltic wave and establish rhythmic contractions. Renal pacemakers have been termed atypical smooth muscle cells due to their low expression of smooth muscle myosin and poor organization of myofilaments compared to typical (or contractile) smooth muscle cells that perform peristalsis. Recent findings discovered that pacemaker cells also express the tyrosine kinase receptor PDGFRα, enabling their identification and purification amongst other renal pelvis cell types. Improved identification methods have determined that the calcium-activated chloride channel, ANO1, is expressed by pacemaker cells and may contribute to spontaneous depolarization. A greater understanding of pacemaker and peristaltic mechanisms is warranted since aberrant contractile function may underlie diseases such as hydronephrosis, a deleterious condition that can cause significant and irreversible nephron injury.
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Affiliation(s)
- Nathan Grainger
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada, USA
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Zhao S, Tang C, Weinberger J, Gao D, Hou S. Sprouting of afferent and efferent inputs to pelvic organs after spinal cord injury. J Neuropathol Exp Neurol 2023; 83:20-29. [PMID: 38102789 PMCID: PMC10746698 DOI: 10.1093/jnen/nlad108] [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] [Indexed: 12/17/2023] Open
Abstract
Neural plasticity occurs within the central and peripheral nervous systems after spinal cord injury (SCI). Although central alterations have extensively been studied, it is largely unknown whether afferent and efferent fibers in pelvic viscera undergo similar morphological changes. Using a rat spinal cord transection model, we conducted immunohistochemistry to investigate afferent and efferent innervations to the kidney, colon, and bladder. Approximately 3-4 weeks after injury, immunostaining demonstrated that tyrosine hydroxylase (TH)-labeled postganglionic sympathetic fibers and calcitonin gene-related peptide (CGRP)-immunoreactive sensory terminals sprout in the renal pelvis and colon. Morphologically, sprouted afferent or efferent projections showed a disorganized structure. In the bladder, however, denser CGRP-positive primary sensory fibers emerged in rats with SCI, whereas TH-positive sympathetic efferent fibers did not change. Numerous CGRP-positive afferents were observed in the muscle layer and the lamina propria of the bladder following SCI. TH-positive efferent inputs displayed hypertrophy with large diameters, but their innervation patterns were sustained. Collectively, afferent or efferent inputs sprout widely in the pelvic organs after SCI, which may be one of the morphological bases underlying functional adaptation or maladaptation.
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Affiliation(s)
- Shunyi Zhao
- Department of Neurobiology and Anatomy, Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, USA
- Department of Pharmacology and Physiology, Drexel University College of Medicine, USA
| | - Chuanxi Tang
- Department of Neurobiology and Cell Biology, Key Laboratory of Neurobiology, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Jeremy Weinberger
- Department of Neurobiology and Anatomy, Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, USA
| | - Dianshuai Gao
- Department of Neurobiology and Cell Biology, Key Laboratory of Neurobiology, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Shaoping Hou
- Department of Neurobiology and Anatomy, Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, USA
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Grainger N, Shonnard CC, Quiggle SK, Fox EB, Presley H, Daugherty R, Shonnard MC, Drumm BT, Sanders KM. Propagation of Pacemaker Activity and Peristaltic Contractions in the Mouse Renal Pelvis Rely on Ca 2+-activated Cl - Channels and T-Type Ca 2+ Channels. FUNCTION (OXFORD, ENGLAND) 2022; 3:zqac041. [PMID: 36325511 PMCID: PMC9614935 DOI: 10.1093/function/zqac041] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 08/15/2022] [Accepted: 08/16/2022] [Indexed: 01/07/2023]
Abstract
The process of urine removal from the kidney occurs via the renal pelvis (RP). The RP demarcates the beginning of the upper urinary tract and is endowed with smooth muscle cells. Along the RP, organized contraction of smooth muscle cells generates the force required to move urine boluses toward the ureters and bladder. This process is mediated by specialized pacemaker cells that are highly expressed in the proximal RP that generate spontaneous rhythmic electrical activity to drive smooth muscle depolarization. The mechanisms by which peristaltic contractions propagate from the proximal to distal RP are not fully understood. In this study, we utilized a transgenic mouse that expresses the genetically encoded Ca2+ indicator, GCaMP3, under a myosin heavy chain promotor to visualize spreading peristaltic contractions in high spatial detail. Using this approach, we discovered variable effects of L-type Ca2+ channel antagonists on contraction parameters. Inhibition of T-type Ca2+ channels reduced the frequency and propagation distance of contractions. Similarly, antagonizing Ca2+-activated Cl- channels or altering the transmembrane Cl- gradient decreased contractile frequency and significantly inhibited peristaltic propagation. These data suggest that voltage-gated Ca2+ channels are important determinants of contraction initiation and maintain the fidelity of peristalsis as the spreading contraction moves further toward the ureter. Recruitment of Ca2+-activated Cl- channels, likely Anoctamin-1, and T-type Ca2+ channels are required for efficiently conducting the depolarizing current throughout the length of the RP. These mechanisms are necessary for the efficient removal of urine from the kidney.
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Affiliation(s)
| | - Cameron C Shonnard
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA
| | - Sage K Quiggle
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA
| | - Emily B Fox
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA
| | - Hannah Presley
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA
| | - Robbie Daugherty
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA
| | - Matthew C Shonnard
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA
| | - Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA,Department of Life and Health Science, Dundalk Institute of Technology, Dublin Road, Dundalk, Co. Louth, A91 K584, Ireland
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV, 89557, USA
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Yoshikawa M, Mitsui R, Takano H, Hashitani H. Mechanosensitive modulation of peristaltic contractions in the mouse renal pelvis. Eur J Pharmacol 2022; 920:174834. [DOI: 10.1016/j.ejphar.2022.174834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 02/02/2022] [Accepted: 02/15/2022] [Indexed: 11/16/2022]
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Liu J, Liu L, Zhao M, Ding N, Ge N, Daugherty SL, Beckel JM, Wang S, Zhang X. Activation of TRPM8 channel inhibits contraction of the isolated human ureter. Neurourol Urodyn 2021; 40:1450-1459. [PMID: 34015169 DOI: 10.1002/nau.24689] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 04/14/2021] [Indexed: 12/19/2022]
Abstract
AIMS The transient receptor potential melastin-8 (TRPM8) channel is a "cooling" receptor expressed in primary sensory neurons and can be activated by compounds like menthol or icilin. TRPM8 is involved in the regulation of urinary bladder sensory function and contraction, but the role of TRPM8 in the ureter, particularly in the human ureter, is poorly understood. The aim of this study is to examine the effects of TRPM8 activation on human ureter contraction. METHODS Human ureters were acquired from 20 patients undergoing radical nephrectomy. Contractions of ureter strips were recorded by an isometric transducer in the organ bath. Ureteral TRPM8 expression in the human ureter was examined by immunofluorescence and western blot. RESULTS The two TRPM8 agonists menthol and icilin both reduced the frequency of spontaneous, electrical field stimulation, or neurokinin A-evoked ureteral contractions in a dose-dependent manner. The inhibitory effects were decreased by 10-fold in mucosa-denuded strips. The inhibitory effects of TRPM8 agonists were mimicked by calcitonin gene-related peptide (CGRP), and were blocked by KRP2579 (a TRPM8 antagonist), tetrodotoxin (a sodium channel blocker), olcegepant (BIBN, a CGRP receptor antagonist), SQ22536 (an adenylate cyclase antagonist), or H89 (a nonspecific cAMP-dependent protein kinase A inhibitor). TRPM8 was coexpressed with CGRP on the nerves located in the suburothelial and intermuscular regions and was not expressed in the urothelium. CONCLUSIONS The TRPM8 channel expressed on sensory nerve terminals of the human ureter is involved in the inhibitory sensory neurotransmission and modulate ureter contraction via the CGRP-adenylyl cyclase-protein kinase A pathway. TRPM8 may be involved in stone-induced changes in ureter contraction or pain.
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Affiliation(s)
- Jiaxin Liu
- Department of Urology, The Second Hospital, Cheeloo College of Medicine, Shandong University, Shandong University, Jinan, Shandong, China
| | - Lei Liu
- Department of Urology, The Second Hospital, Cheeloo College of Medicine, Shandong University, Shandong University, Jinan, Shandong, China
| | - Mengmeng Zhao
- Department of Urology, The Second Hospital, Cheeloo College of Medicine, Shandong University, Shandong University, Jinan, Shandong, China
| | - Ning Ding
- Department of Urology, The Second Hospital, Cheeloo College of Medicine, Shandong University, Shandong University, Jinan, Shandong, China
| | - Nan Ge
- Department of Urology, The Second Hospital, Cheeloo College of Medicine, Shandong University, Shandong University, Jinan, Shandong, China
| | - Stephanie L Daugherty
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Jonathan M Beckel
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Shaoyong Wang
- Department of Urology, The Second Hospital, Cheeloo College of Medicine, Shandong University, Shandong University, Jinan, Shandong, China
| | - Xiulin Zhang
- Department of Urology, The Second Hospital, Cheeloo College of Medicine, Shandong University, Shandong University, Jinan, Shandong, China
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Liu J, Zhao M, Chen Z, Xu Y, Guo L, Wang S, Li Y, Shi B, Zhang X, Jin XD. TRPM3 channel activation inhibits contraction of the isolated human ureter via CGRP released from sensory nerves. Life Sci 2021; 268:118967. [PMID: 33417951 DOI: 10.1016/j.lfs.2020.118967] [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: 11/12/2020] [Revised: 12/18/2020] [Accepted: 12/21/2020] [Indexed: 11/29/2022]
Abstract
AIMS Sensory nerve activation modulates ureteral contractility by releasing neuropeptides including CGRP and neurokinin A (NKA). TRPM3 is a recently discovered thermosensitive channel expressed in nociceptive sensory neurons, and plays a key role in heat nociception and chronic pain. The aim of this study is to examine the role of TRPM3 activation in human ureter motility. MAIN METHOD Human proximal ureters were obtained from fourteen patients undergoing nephrectomy. Spontaneous or NKA-evoked contractions of longitudinal ureter strips were recorded in an organ bath. Ureteral TRPM3 expression was examined by immunofluorescence. KEY FINDINGS Spontaneous contractions were observed in 60% of examined strips. TRPM3 activation using pregnenolone sulphate (PS) or CIM0216 (specific TRPM3 agonists) dose-dependently reduced the frequency of spontaneous and NKA-evoked contractions, with IC50s of 241.7 μM and 4.4 μM, respectively. The inhibitory actions of TRPM3 agonists were mimicked by CGRP (10 to 100 nM) or a cAMP analogue (8-Br-cAMP; 1 mM). The inhibitory actions of TRPM3 agonists (300 μM PS or 30 μM CIM0216) were blocked by pretreatment with primidone (TRPM3 antagonist; 30 μM), tetrodotoxin (sodium channel blocker; 1 μM), olcegepant (CGRP receptor antagonist; 10 μM), or H89 (non-specific PKA inhibitor; 30 μM). TRPM3 was co-expressed with CGRP in nerves in the sub-urothelial and intermuscular regions of the ureter. SIGNIFICANCE TRPM3 channels expressed on sensory terminals of the human ureter involve in inhibitory sensory neurotransmission and modulate ureter motility via the CGRP-cAMP-PKA signal pathway. Targeting TRPM3 may be a pharmacological strategy for promoting the ureter stone passage.
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Affiliation(s)
- Jiaxin Liu
- The First Affiliated Hospital, College of Medicine, Zhejiang University, China
| | - Mengmeng Zhao
- Department of Urology, The Second Hospital, Cheeloo College of Medicine, Shandong University, China
| | - Zhenghao Chen
- Department of Urology, The Second Hospital, Cheeloo College of Medicine, Shandong University, China
| | - Yang Xu
- Department of Urology, The Second Hospital, Cheeloo College of Medicine, Shandong University, China
| | - Liqiang Guo
- Department of Urology, The Second Hospital, Cheeloo College of Medicine, Shandong University, China
| | - Shaoyong Wang
- Department of Urology, The Second Hospital, Cheeloo College of Medicine, Shandong University, China
| | - Yan Li
- Department of Urology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, China
| | - Benkang Shi
- Department of Urology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, China
| | - Xiulin Zhang
- Department of Urology, The Second Hospital, Cheeloo College of Medicine, Shandong University, China.
| | - Xiao-Dong Jin
- The First Affiliated Hospital, College of Medicine, Zhejiang University, China.
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Hashitani H, Mitsui R, Lang R. Functional heterogeneity of PDGFRα (+) cells in spontaneously active urogenital tissues. Neurourol Urodyn 2020; 39:1667-1678. [PMID: 32531084 DOI: 10.1002/nau.24431] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 06/02/2020] [Indexed: 11/06/2022]
Abstract
AIMS As PDGFRα (+) cells appear not to suppress the excitability of detrusor smooth muscle by generating SK3-dependent hyperpolarising as proposed in the gastrointestinal tract, we further explored the functional roles of PDGFRα (+) cells in regulating the spontaneous activity of urogenital tissues. METHODS Using PDGFRα-eGFP mice, intracellular Ca2+ signaling in PDGFRα (+) cells of the bladder lamina propria, renal pelvis, and seminal vesicle were visualized using Cal-590 fluorescence. The distribution and SK3 expression of PDGFRα (+) cells were also examined by immunohistochemistry. RESULTS In the bladder lamina propria, SK3 (-) PDGFRα (+) cells exhibited spontaneous Ca2+ transients and responded to stimulation of P2Y1 purinoceptors with MRS2365 (100 nM) or adenosine diphosphate (ADP) (100 μM) by developing Ca2+ transients. In the proximal renal pelvis, PDGFRα (+) cells were distributed in the mucosal, muscular and serosal layers but did not express SK3 immunoreactivity. PDGFRα (+) cells in the musculature resembling atypical smooth muscle cells generated spontaneous Ca2+ transients that were partially suppressed upon P2Y1-stimulation, while vigorously responding to human angiotensin II (100 nM). In the seminal vesicle, PDGFRα (+) cells in the musculature but not mucosa expressed SK3 immunoreactivity. In the mucosa, the P2Y1 stimulation evoked Ca2+ transients in both PDGFRα (+) cells and PDGFRα (-) cells. CONCLUSION PDGFRα (+) cells in spontaneously active urogenital tissues display heterogeneity in terms of their SK3 expression and P2Y1-induced Ca2+ responses. Muscular PDGFRα (+) cells in the renal pelvis and mucosal PDGFRα (+) cells in the seminal vesicle may generate depolarizing signals to drive smooth muscle cells.
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Affiliation(s)
- Hikaru Hashitani
- Department of Cell Physiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Retsu Mitsui
- Department of Cell Physiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Richard Lang
- Department of Physiology, Monash University, Clayton, Victoria, Australia
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Grainger N, Freeman RS, Shonnard CC, Drumm BT, Koh SD, Ward SM, Sanders KM. Identification and classification of interstitial cells in the mouse renal pelvis. J Physiol 2020; 598:3283-3307. [PMID: 32415739 DOI: 10.1113/jp278888] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Accepted: 04/29/2020] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS Platelet-derived growth factor receptor-α (PDGFRα) is a novel biomarker along with smooth myosin heavy chain for the pacemaker cells (previously termed 'atypical' smooth muscle cells) in the murine and cynomolgus monkey pelvis-kidney junction. PDGFRα+ cells present in adventitial and urothelial layers of murine renal pelvis do not express smooth muscle myosin heavy chain (smMHC) but are in close apposition to nerve fibres. Most c-Kit+ cells in the renal pelvis are mast cells. Mast cells (CD117+ /CD45+ ) are more abundant in the proximal renal pelvis and pelvis-kidney junction regions whereas c-Kit+ interstitial cells (CD117+ /CD45- ) are found predominantly in the distal renal pelvis and ureteropelvic junction. PDGFRα+ cells are distinct from c-Kit+ interstitial cells. A subset of PDGFRα+ cells express the Ca2+ -activated Cl- channel, anoctamin-1, across the entire renal pelvis. Spontaneous Ca2+ transients were observed in c-Kit+ interstitial cells, smMHC+ PDGFRα cells and smMHC- PDGFRα cells using mice expressing genetically encoded Ca2+ sensors. ABSTRACT Rhythmic contractions of the renal pelvis transport urine from the kidneys into the ureter. Specialized pacemaker cells, termed atypical smooth muscle cells (ASMCs), are thought to drive the peristaltic contractions of typical smooth muscle cells (TSMCs) in the renal pelvis. Interstitial cells (ICs) in close proximity to ASMCs and TSMCs have been described, but the role of these cells is poorly understood. The presence and distributions of platelet-derived growth factor receptor-α+ (PDGFRα+ ) ICs in the pelvis-kidney junction (PKJ) and distal renal pelvis were evaluated. We found PDGFRα+ ICs in the adventitial layers of the pelvis, the muscle layer of the PKJ and the adventitia of the distal pelvis. PDGFRα+ ICs were distinct from c-Kit+ ICs in the renal pelvis. c-Kit+ ICs are a minor population of ICs in murine renal pelvis. The majority of c-Kit+ cells were mast cells. PDGFRα+ cells in the PKJ co-expressed smooth muscle myosin heavy chain (smMHC) and several other smooth muscle gene transcripts, indicating these cells are ASMCs, and PDGFRα is a novel biomarker for ASMCs. PDGFRα+ cells also express Ano1, which encodes a Ca2+ -activated Cl- conductance that serves as a primary pacemaker conductance in ICs of the GI tract. Spontaneous Ca2+ transients were observed in c-Kit+ ICs, smMHC+ PDGFRα cells and smMHC- PDGFRα cells using genetically encoded Ca2+ sensors. A reporter strain of mice with enhanced green fluorescent protein driven by the endogenous promotor for Pdgfra was shown to be a powerful new tool for isolating and characterizing the phenotype and functions of these cells in the renal pelvis.
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Affiliation(s)
- Nathan Grainger
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Ryan S Freeman
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Cameron C Shonnard
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Bernard T Drumm
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Sang Don Koh
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Sean M Ward
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Kenton M Sanders
- Department of Physiology & Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
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Role of Pericytes in the Initiation and Propagation of Spontaneous Activity in the Microvasculature. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1124:329-356. [PMID: 31183834 DOI: 10.1007/978-981-13-5895-1_14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The microvasculature is composed of arterioles, capillaries and venules. Spontaneous arteriolar constrictions reduce effective vascular resistance to enhance tissue perfusion, while spontaneous venular constrictions facilitate the drainage of tissue metabolites by pumping blood. In the venules of visceral organs, mural cells, i.e. smooth muscle cells (SMCs) or pericytes, periodically generate spontaneous phasic constrictions, Ca2+ transients and transient depolarisations. These events arise from spontaneous Ca2+ release from the sarco-endoplasmic reticulum (SR/ER) and the subsequent opening of Ca2+-activated chloride channels (CaCCs). CaCC-dependent depolarisation further activates L-type voltage-dependent Ca2+ channels (LVDCCs) that play a critical role in maintaining the synchrony amongst mural cells. Mural cells in arterioles or capillaries are also capable of developing spontaneous activity. Non-contractile capillary pericytes generate spontaneous Ca2+ transients primarily relying on SR/ER Ca2+ release. Synchrony amongst capillary pericytes depends on gap junction-mediated spread of depolarisations resulting from the opening of either CaCCs or T-type VDCCs (TVDCCs) in a microvascular bed-dependent manner. The propagation of capillary Ca2+ transients into arterioles requires the opening of either L- or TVDCCs again depending on the microvascular bed. Since the blockade of gap junctions or CaCCs prevents spontaneous Ca2+ transients in arterioles and venules but not capillaries, capillary pericytes appear to play a primary role in generating spontaneous activity of the microvasculature unit. Pericytes in capillaries where the interchange of substances between tissues and the circulation takes place may provide the fundamental drive for upstream arterioles and downstream venules so that the microvasculature network functions as an integrated unit.
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Mitsui R, Hashitani H. Role of K + channels in maintaining the synchrony of spontaneous Ca 2+ transients in the mural cells of rat rectal submucosal arterioles. Pflugers Arch 2019; 471:1025-1040. [PMID: 30982085 DOI: 10.1007/s00424-019-02274-3] [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] [Received: 01/25/2019] [Revised: 03/13/2019] [Accepted: 03/27/2019] [Indexed: 02/07/2023]
Abstract
Mural cells in precapillary arterioles (PCAs) generate spontaneous Ca2+ transients primarily arising from the periodic release of Ca2+ from sarcoendoplasmic reticulum (SR/ER). The Ca2+ release induces Ca2+-activated chloride channel (CaCC)-dependent depolarisations that spread to neighbouring mural cells to develop the synchrony of their Ca2+ transients. Here, we explored the roles of K+ channels in maintaining the synchrony of spontaneous Ca2+ transients. Intracellular Ca2+ dynamics in mural cells were visualised by Cal-520 fluorescence Ca2+ imaging in the submucosal PCAs of rat rectum. Increasing extracellular K+ concentration ([K+]o) from 5.9 to 29.7 mM converted synchronous spontaneous Ca2+ transients into asynchronous, high-frequency Ca2+ transients. Similarly, the blockade of inward rectifier K+ (Kir) channels with Ba2+ (50 μM) or Kv7 voltage-dependent K+ (Kv7) channels with XE 991 (10 μM) disrupted the synchrony of spontaneous Ca2+ transients, while the blockers for large-, intermediate- or small-conductance Ca2+-activated K+ channels had no effect. Kir2.1 immunoreactivity was detected in the arteriolar endothelium but not mural cells. In the PCAs that had been pretreated with XE 991 or Ba2+, nifedipine (1 μM) attenuated the asynchronous Ca2+ transients but failed to restore their synchrony. In contrast, levcromakalim, an ATP-sensitive K+ channel opener, restored the synchronous Ca2+ transients. Thus, constitutively active Kv7 and Kir channels appear to be involved in maintaining the relatively hyperpolarised membrane of mural cells. The hyperpolarised membrane prevents depolarisation-induced 'premature' Ca2+ transients to ensure sufficient SR/ER Ca2+ refilling that is required for regenerative Ca2+ release resulting in synchronous Ca2+ transients amongst the mural cells.
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Affiliation(s)
- Retsu Mitsui
- Department of Cell Physiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
| | - Hikaru Hashitani
- Department of Cell Physiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
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Lang RJ, Hashitani H. Pacemaker Mechanisms Driving Pyeloureteric Peristalsis: Modulatory Role of Interstitial Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1124:77-101. [PMID: 31183823 DOI: 10.1007/978-981-13-5895-1_3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
The peristaltic pressure waves in the renal pelvis that propel urine expressed by the kidney into the ureter towards the bladder have long been considered to be 'myogenic', being little affected by blockers of nerve conduction or autonomic neurotransmission, but sustained by the intrinsic release of prostaglandins and sensory neurotransmitters. In uni-papilla mammals, the funnel-shaped renal pelvis consists of a lumen-forming urothelium and a stromal layer enveloped by a plexus of 'typical' smooth muscle cells (TSMCs), in multi-papillae kidneys a number of minor and major calyces fuse into a large renal pelvis. Electron microscopic, electrophysiological and Ca2+ imaging studies have established that the pacemaker cells driving pyeloureteric peristalsis are likely to be morphologically distinct 'atypical' smooth muscle cells (ASMCs) that fire Ca2+ transients and spontaneous transient depolarizations (STDs) which trigger propagating nifedipine-sensitive action potentials and Ca2+ waves in the TSMC layer. In uni-calyceal kidneys, ASMCs predominately locate on the serosal surface of the proximal renal pelvis while in multi-papillae kidneys they locate within the sub-urothelial space. 'Fibroblast-like' interstitial cells (ICs) located in the sub-urothelial space or adventitia are a mixed population of cells, having regional and species-dependent expression of various Cl-, K+, Ca2+ and cationic channels. ICs display asynchronous Ca2+ transients that periodically synchronize into bursts that accelerate ASMC Ca2+ transient firing. This review presents current knowledge of the architecture of the proximal renal pelvis, the role Ca2+ plays in renal pelvis peristalsis and the mechanisms by which ICs may sustain/accelerate ASMC pacemaking.
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Affiliation(s)
- Richard J Lang
- School of Biomedical Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia.
| | - Hikaru Hashitani
- Department of Cell Physiology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan
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Hashitani H, Nguyen MJ, Noda H, Mitsui R, Higashi R, Ohta K, Nakamura KI, Lang RJ. Interstitial cell modulation of pyeloureteric peristalsis in the mouse renal pelvis examined using FIBSEM tomography and calcium indicators. Pflugers Arch 2017; 469:797-813. [PMID: 28054154 DOI: 10.1007/s00424-016-1930-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 12/12/2016] [Indexed: 12/28/2022]
Abstract
Typical and atypical smooth muscle cells (TSMCs and ASMCs, respectively) and interstitial cells (ICs) within the pacemaker region of the mouse renal pelvis were examined using focused ion beam scanning electron (FIB SEM) tomography, immunohistochemistry and Ca2+ imaging. Individual cells within 500-900 electron micrograph stacks were volume rendered and associations with their neighbours established. 'Ribbon-shaped', Ano1 Cl- channel immuno-reactive ICs were present in the adventitia and the sub-urothelial space adjacent to the TSMC layer. ICs in the proximal renal pelvis were immuno-reactive to antibodies for CaV3.1 and hyperpolarization-activated cation nucleotide-gated isoform 3 (HCN3) channel sub-units, while basal-epithelial cells (BECs) were intensely immuno-reactive to Kv7.5 channel antibodies. Adventitial to the TSMC layer, ASMCs formed close appositions with TSMCs and ICs. The T-type Ca2+channel blocker, Ni2+ (10-200 μM), reduced the frequency while the L-type Ca2+ channel blocker (1 μM nifedipine) reduced the amplitude of propagating Ca2+ waves and contractions in the TSMC layer. Upon complete suppression of Ca2+ entry through TSMC Ca2+ channels, ASMCs displayed high-frequency (6 min-1) Ca2+ transients, and ICs distributed into two populations of cells firing at 1 and 3 min-1, respectively. IC Ca2+ transients periodically (every 3-5 min-1) summed into bursts which doubled the frequency of ASMC Ca2+ transient firing. Synchronized IC bursting and the acceleration of ASMC firing were inhibited upon blockade of HCN channels with ZD7288 or cell-to-cell coupling with carbenoxolone. While ASMCs appear to be the primary pacemaker driving pyeloureteric peristalsis, it was concluded that sub-urothelial HCN3(+), CaV3.1(+) ICs can accelerate ASMC Ca2+ signalling.
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Affiliation(s)
- Hikaru Hashitani
- Department of Cell Physiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, 467-8601, Japan
| | - Michael J Nguyen
- Department of Pharmacology, School of Biomedical Sciences, Monash University, Clayton, VIC, 3800, Australia
| | - Haruka Noda
- Department of Cell Physiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, 467-8601, Japan
| | - Retsu Mitsui
- Department of Cell Physiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, 467-8601, Japan
| | - Ryuhei Higashi
- Department of Anatomy, Kurume University School of Medicine, Kurume, Japan
| | - Keisuke Ohta
- Department of Anatomy, Kurume University School of Medicine, Kurume, Japan
| | | | - Richard J Lang
- Department of Pharmacology, School of Biomedical Sciences, Monash University, Clayton, VIC, 3800, Australia.
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Nguyen M, Higashi R, Ohta K, Nakamura KI, Hashitani H, Lang R. Autonomic and sensory nerve modulation of peristalsis in the upper urinary tract. Auton Neurosci 2016; 200:1-10. [DOI: 10.1016/j.autneu.2015.07.425] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 07/20/2015] [Accepted: 07/28/2015] [Indexed: 11/24/2022]
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Steinbach A, Schaper K, Koenen A, Schlüter T, Zimmermann U, Rettig R, Grisk O. Role of endothelin-1 for the regulation of renal pelvic function. Pflugers Arch 2016; 468:1467-78. [DOI: 10.1007/s00424-016-1848-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 05/17/2016] [Accepted: 06/06/2016] [Indexed: 10/21/2022]
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15
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Almukhtar H, Garle M, Smith P, Roberts R. Effect of simvastatin on vascular tone in porcine coronary artery: Potential role of the mitochondria. Toxicol Appl Pharmacol 2016; 305:176-185. [DOI: 10.1016/j.taap.2016.06.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 06/08/2016] [Accepted: 06/21/2016] [Indexed: 12/17/2022]
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Nguyen MJ, Hashitani H, Lang RJ. Angiotensin receptor-1A knockout leads to hydronephrosis not associated with a loss of pyeloureteric peristalsis in the mouse renal pelvis. Clin Exp Pharmacol Physiol 2016; 43:535-42. [DOI: 10.1111/1440-1681.12560] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 02/07/2016] [Accepted: 02/09/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Michael J Nguyen
- Department of Physiology; School of Biomedical Sciences; Monash University; Clayton Victoria Australia
| | - Hikaru Hashitani
- Department of Cell Physiology; Nagoya City University Graduate School of Medical Sciences; Nagoya Japan
| | - Richard J Lang
- Department of Physiology; School of Biomedical Sciences; Monash University; Clayton Victoria Australia
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Hashitani H, Lang RJ. Spontaneous activity in the microvasculature of visceral organs: role of pericytes and voltage-dependent Ca(2+) channels. J Physiol 2016; 594:555-65. [PMID: 26607499 DOI: 10.1113/jp271438] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 10/31/2015] [Indexed: 12/21/2022] Open
Abstract
The microvasculature plays a primary role in the interchange of substances between tissues and the circulation. In visceral organs that undergo considerable distension upon filling, the microvasculature appears to display intrinsic contractile properties to maintain their flow. Submucosal venules in the bladder or gastrointestinal tract generate rhythmic spontaneous phasic constrictions and associated Ca(2+) transients. These events are initiated within either venular pericytes or smooth muscle cells (SMCs) arising from spontaneous Ca(2+) release from the sarcoplasmic reticulum (SR) and the opening of Ca(2+) -activated chloride channels (CaCCs) that trigger Ca(2+) influx through L-type voltage-dependent Ca(2+) channels (VDCCs). L-type VDCCs also play a critical role in maintaining synchrony within the contractile mural cells. In the stomach myenteric layer, spontaneous Ca(2+) transients originating in capillary pericytes appear to spread to their neighbouring arteriolar SMCs. Capillary Ca(2+) transients primarily rely on SR Ca(2+) release, but also require Ca(2+) influx through T-type VDCCs for their synchrony. The opening of T-type VDCCs also contribute to the propagation of Ca(2+) transients into SMCs. In visceral microvasculature, pericytes act as either spontaneously active contractile machinery of the venules or as pacemaker cells generating synchronous Ca(2+) transients that drive spontaneous contractions in upstream arterioles. Thus pericytes play different roles in different vascular beds in a manner that may well depend on the selective expression of T-type and L-type Ca(2+) channels.
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Affiliation(s)
- Hikaru Hashitani
- Department of Cell Physiology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan
| | - Richard J Lang
- Department of Physiology, School of Biomedical Sciences, Monash University, Clayton, Victoria, 3800, Australia
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Nguyen MJ, Angkawaijawa S, Hashitani H, Lang RJ. Nicotinic receptor activation on primary sensory afferents modulates autorhythmicity in the mouse renal pelvis. Br J Pharmacol 2014; 170:1221-32. [PMID: 24004375 DOI: 10.1111/bph.12395] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Revised: 08/19/2013] [Accepted: 08/27/2013] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE The modulation of the spontaneous electrical and Ca(2+) signals underlying pyeloureteric peristalsis upon nicotinic receptor activation located on primary sensory afferents (PSAs) was investigated in the mouse renal pelvis. EXPERIMENTAL APPROACH Contractile activity was followed using video microscopy, electrical and Ca(2+) signals in typical and atypical smooth muscle cells (TSMCs and ASMCs) within the renal pelvis were recorded separately using intracellular microelectrodes and Fluo-4 Ca(2+) imaging. KEY RESULTS Nicotine and carbachol (CCh; 1-100 μM) transiently reduced the frequency and increased the amplitude of spontaneous phasic contractions in a manner unaffected by muscarininc antagonists, 4-DAMP (1,1-dimethyl-4-diphenylacetoxypiperidinium iodide) and pirenzipine (10 nM) or L-NAME (L-Nω-nitroarginine methyl ester; 200 μM), inhibitor of NO synthesis, but blocked by the nicotinic antagonist, hexamethonium or capsaicin, depletor of PSA neuropeptides. These negative chronotropic and delayed positive inotropic effects of CCh on TSMC contractions, action potentials and Ca(2+) transients were inhibited by glibenclamide (Glib; 1 μM), blocker of ATP-dependent K (KATP) channels. Nicotinic receptor-evoked inhibition of the spontaneous Ca(2+) transients in ASMCs was prevented by capsaicin but not Glib. In contrast, the negative inotropic and chronotropic effects of the non-selective COX inhibitor indomethacin were not prevented by Glib. CONCLUSIONS AND IMPLICATIONS The negative chronotropic effect of nicotinic receptor activation results from the release of calcitonin gene-related peptide (CGRP) from PSAs, which suppresses Ca(2+) signalling in ASMCs. PSA-released CGRP also evokes a transient hyperpolarization in TSMCs upon the opening of KATP channels, which reduces contraction propagation but promotes the recruitment of TSMC Ca(2+) channels that underlie the delayed positive inotropic effects of CCh.
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Affiliation(s)
- M J Nguyen
- Department of Physiology, School of Biomedical Sciences, Monash University, Clayton, Vic., Australia
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Nishikawa N, Kanematsu A, Negoro H, Imamura M, Sugino Y, Okinami T, Yoshimura K, Hashitani H, Ogawa O. PTHrP is endogenous relaxant for spontaneous smooth muscle contraction in urinary bladder of female rat. Endocrinology 2013; 154:2058-68. [PMID: 23546599 DOI: 10.1210/en.2012-2142] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Acute bladder distension causes various morphologic and functional changes, in part through altered gene expression. We aimed to investigate the physiologic role of PTHrP, which is up-regulated in an acute bladder distension model in female rats. In the control Empty group, bladders were kept empty for 6 hours, and in the Distension group, bladders were kept distended for 3 hours after an artificial storing-voiding cycle for 3 hours. In the Distention group bladder, up-regulation of transcripts was noted for 3 genes reported to be up-regulated by stretch in the cultured bladder smooth muscle cells in vitro. Further transcriptome analysis by microarray identified PTHrP as the 22nd highest gene up-regulated in Distension group bladder, among more than 27,000 genes. Localization of PTHrP and its functional receptor, PTH/PTHrP receptor 1 (PTH1R), were analyzed in the untreated rat bladders and cultured bladder cells using real-time RT-PCR and immunoblotting, which revealed that PTH1R and PTHrP were more predominantly expressed in smooth muscle than in urothelium. Exogenous PTHrP peptide (1-34) increased intracellular cAMP level in cultured bladder smooth muscle cells. In organ bath study using bladder strips, the PTHrP peptide caused a marked reduction in the amplitude of spontaneous contraction but caused only modest suppression for carbachol-induced contraction. In in vivo functional study by cystometrogram, the PTHrP peptide decreased voiding pressure and increased bladder compliance. Thus, PTHrP is a potent endogenous relaxant of bladder contraction, and autocrine or paracrine mechanism of the PTHrP-PTH1R axis is a physiologically relevant pathway functioning in the bladder.
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MESH Headings
- Animals
- Carbachol/pharmacology
- Cells, Cultured
- Cholinergic Agonists/pharmacology
- Cyclic AMP/metabolism
- Female
- Gene Expression Profiling
- Immunoblotting
- In Vitro Techniques
- Muscle Contraction/genetics
- Muscle Contraction/physiology
- Muscle, Smooth/metabolism
- Muscle, Smooth/physiopathology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Oligonucleotide Array Sequence Analysis
- Parathyroid Hormone-Related Protein/genetics
- Parathyroid Hormone-Related Protein/metabolism
- Parathyroid Hormone-Related Protein/physiology
- Peptide Fragments/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptor, Parathyroid Hormone, Type 1/genetics
- Receptor, Parathyroid Hormone, Type 1/metabolism
- Receptor, Parathyroid Hormone, Type 1/physiology
- Reverse Transcriptase Polymerase Chain Reaction
- Urinary Bladder/metabolism
- Urinary Bladder/physiopathology
- Urinary Retention/genetics
- Urinary Retention/metabolism
- Urinary Retention/physiopathology
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Affiliation(s)
- Nobuyuki Nishikawa
- Department of Urology, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan
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Iqbal J, Tonta MA, Mitsui R, Li Q, Kett M, Li J, Parkington HC, Hashitani H, Lang RJ. Potassium and ANO1/ TMEM16A chloride channel profiles distinguish atypical and typical smooth muscle cells from interstitial cells in the mouse renal pelvis. Br J Pharmacol 2012; 165:2389-408. [PMID: 22014103 DOI: 10.1111/j.1476-5381.2011.01730.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Although atypical smooth muscle cells (SMCs) in the proximal renal pelvis are thought to generate the pacemaker signals that drive pyeloureteric peristalsis, their location and electrical properties remain obscure. EXPERIMENTAL APPROACH Standard patch clamp, intracellular microelectrode and immunohistochemistry techniques were used. To unequivocally identify SMCs, transgenic mice with enhanced yellow fluorescent protein (eYFP) expressed in cells containing α-smooth muscle actin (α-SMA) were sometimes used. KEY RESULTS Atypical SMCs were distinguished from typical SMCs by the absence of both a transient 4-aminopyridine-sensitive K(+) current (I(KA) ) and spontaneous transient outward currents (STOCs) upon the opening of large-conductance Ca(2+) -activated K(+) (BK) channels. Many typical SMCs displayed a slowly activating, slowly decaying Cl(-) current blocked by niflumic acid (NFA). Immunostaining for K(V) 4.3 and ANO1/ TMEM16A Cl(-) channel subunits co-localized with α-SMA immunoreactive product predominately in the distal renal pelvis. Atypical SMCs fired spontaneous inward currents that were either selective for Cl(-) and blocked by NFA, or cation-selective and blocked by La(3+) . α-SMA(-) interstitial cells (ICs) were distinguished by the presence of a Xe991-sensitive K(V) 7 current, BK channel STOCs and Cl(-) selective, NFA-sensitive spontaneous transient inward currents (STICs). Intense ANO1/ TMEM16A and K(V) 7.5 immunostaining was present in Kit(-) α-SMA(-) ICs in the suburothelial and adventitial regions of the renal pelvis. CONCLUSIONS AND IMPLICATIONS We conclude that K(V) 4.3(+) α-SMA(+) SMCs are typical SMCs that facilitate muscle wall contraction, that ANO1/ TMEM16A and K(V) 7.5 immunoreactivity may be selective markers of Kit(-) ICs and that atypical SMCs which discharge spontaneous inward currents are the pelviureteric pacemakers.
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Affiliation(s)
- Javed Iqbal
- Department of Physiology Anatomy & Development Biology, Monash University, Clayton, Victoria, Australia
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Shigemasa Y, Kito Y, Hashitani H, Suzuki H. Factors which determine the duration of follower potentials in longitudinal smooth muscle isolated from the guinea-pig stomach antrum. J Smooth Muscle Res 2011; 47:89-110. [PMID: 21979408 DOI: 10.1540/jsmr.47.89] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In isolated longitudinal muscle tissues of the guinea-pig stomach antrum, recording electrical responses from smooth muscle cells revealed a periodical generation of follower potentials with variable durations. The I-D relationship, made by plotting the duration as a function of the interval before generating follower potential, was linear. Experiments were carried out to investigate the effects of chemicals which had been known to modulate the release of Ca(2+) from the internal stores (2-aminoethoxy-diphenyl-borate, cyclopiazonic acid, caffeine), inhibit mitochondrial metabolic activity (m-chlorophenyl hydrazone, 2-deoxy-D-glucose, potassium cyanide, rotenone), inhibit ATP-sensitive K-channels distributed in mitochondria (glibenclamide, 5-hydroxydecanoic acid) and inhibit the activity of proteinkinase C (chelerythrine), on the I-D relationship of follower potentials. The effects of depolarization on follower potentials were assessed by stimulating tissues with high potassium solution. Experiments were carried out mainly in the presence of nifedipine which minimized the movements of muscles with no modulation of follower potentials. Cycropiazonic acid and caffeine reduced the slope of I-D relationship, with associated reduction of the duration and frequency of follower potentials. 2-Aminoethoxydiphenyl borate reduced the duration and amplitude and increased the frequency of follower potentials, with depolarization of the membrane, and the effects were simulated by high potassium solution. m-Chlorophenyl hydrazone, potassium cyanide, 2-deoxy-D-glucose, rotenone, 5-hydroxydecanoic acid and glibenclamide reduced the slope of I-D relationship, with associated reduction of the frequency of follower potentials. Chelerythrine did not modulate the slope of I-D relationship, with reduced frequency of follower potentials. It seemed likely that the amount of Ca(2+) released from the internal stores and also mitochondrial function had causal relationship to the duration of pacemaker potentials, suggesting that internal Ca-stores and mitochondria are taking the central role for determining the duration of the pacemaker activity. Proteinkinase C did not seem to participate to the function of mitochondria and internal Ca(2+) stores.
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Affiliation(s)
- Yuhsuke Shigemasa
- Department of Cell Physiology, Nagoya City University Medical School, Mizuho-ku, Nagoya, Japan
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Hashitani H, Hashiatni H, Lang RJ, Suzuki H. Role of perinuclear mitochondria in the spatiotemporal dynamics of spontaneous Ca2+ waves in interstitial cells of Cajal-like cells of the rabbit urethra. Br J Pharmacol 2011; 161:680-94. [PMID: 20880405 DOI: 10.1111/j.1476-5381.2010.00902.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Although spontaneous Ca(2+) waves in interstitial cells of Cajal (ICC)-like cells (ICC-LCs) primarily arise from endoplasmic reticulum (ER) Ca(2+) release, the interactions among mitochondrial Ca(2+) buffering, cellular energetics and ER Ca(2+) release in determining the spatiotemporal dynamics of intracellular Ca(2+) remain to be elucidated. EXPERIMENTAL APPROACH Spontaneous Ca(2+) transients in freshly isolated ICC-LCs of the rabbit urethra were visualized using fluo-4 Ca(2+) imaging, while the intracellular distribution of mitochondria was viewed with MitoTracker Red. KEY RESULTS Spontaneous Ca(2+) waves invariably originated from the perinuclear region where clusters of mitochondria surround the nucleus. Perinuclear Ca(2+) dynamics were characterized by a gradual rise in basal Ca(2+) that preceded each regenerative Ca(2+) transient. Caffeine evoked oscillatory Ca(2+) waves originating from anywhere within ICC-LCs. Ryanodine or cyclopiazonic acid prevented Ca(2+) wave generation with a rise in basal Ca(2+), and subsequent caffeine evoked a single rudimentary Ca(2+) transient. Inhibition of glycolysis with 2-deoxy-glucose or carbonyl cyanide 3-chlorophenylhydrazone, a mitochondrial protonophore, increased basal Ca(2+) and abolished Ca(2+) waves. However, caffeine still induced oscillatory Ca(2+) transients. Mitochondrial Ca(2+) uptake inhibition with RU360 attenuated Ca(2+) wave amplitudes, while mitochondrial Ca(2+) efflux inhibition with CGP37157 suppressed the initial Ca(2+) rise to reduce Ca(2+) wave frequency. CONCLUSIONS AND IMPLICATIONS Perinuclear mitochondria in ICC-LCs play a dominant role in the spatial regulation of Ca(2+) wave generation and may regulate ER Ca(2+) release frequency by buffering Ca(2+) within microdomains between both organelles. Glycolysis inhibition reduced mitochondrial Ca(2+) buffering without critically disrupting ER function. Perinuclear mitochondria may function as sensors of intracellular metabolites.
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Affiliation(s)
- Hikaru Hashitani
- Department of Cell Physiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
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Abstract
Interstitial cells of Cajal (ICC)-like cells (ICC-LCs) have been identified in many regions of the urinary tract and male genital organs by immunohistochemical studies and electron microscopy. ICC-LCs are characterized by their spontaneous electrical and Ca2+ signalling and the cellular mechanisms of their generation have been extensively investigated. Spontaneous activity in ICC-LCs rises from the release of internally stored Ca2+ and the opening of Ca2+-activated Cl− channels to generate spontaneous transient depolarizations (STDs) in a manner not fundamentally dependent on Ca2+ influx through L-type voltage-dependent Ca2+ channels. Since urogenital ICC-LCs have been identified by their immunoreactivity to Kit (CD117) antibodies, the often-used specific marker for ICC in the gastrointestinal tract, their functions have been thought likely to be similar. Thus ICC-LCs in the urogenital tract might be expected to act as either electrical pacemaker cells to drive the smooth muscle wall or as intermediaries in neuromuscular transmission. However, present knowledge of the functions of ICC-LCs suggests that their functions are not so predetermined, that their functions may be very region specific, particularly under pathological conditions. In this review, we summarize recent advances in our understanding of the location and function of ICC-LCs in various organs of the urogenital system. We also discuss several unsolved issues regarding the identification, properties and functions of ICC-LCs in various urogenital regions in health and disease.
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Affiliation(s)
- Hikaru Hashitani
- Department of Cell Physiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
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