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Cho HY, Chuang TH, Wu SN. The Effectiveness in Activating M-Type K + Current Produced by Solifenacin ([(3R)-1-azabicyclo[2.2.2]octan-3-yl] (1S)-1-phenyl-3,4-dihydro-1H-isoquinoline-2-carboxylate): Independent of Its Antimuscarinic Action. Int J Mol Sci 2021; 22:ijms222212399. [PMID: 34830281 PMCID: PMC8622881 DOI: 10.3390/ijms222212399] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 11/08/2021] [Accepted: 11/15/2021] [Indexed: 12/18/2022] Open
Abstract
Solifenacin (Vesicare®, SOL), known to be a member of isoquinolines, is a muscarinic antagonist that has anticholinergic effect, and it has been beneficial in treating urinary incontinence and neurogenic detrusor overactivity. However, the information regarding the effects of SOL on membrane ionic currents is largely uncertain, despite its clinically wide use in patients with those disorders. In this study, the whole-cell current recordings revealed that upon membrane depolarization in pituitary GH3 cells, the exposure to SOL concentration-dependently increased the amplitude of M-type K+ current (IK(M)) with effective EC50 value of 0.34 μM. The activation time constant of IK(M) was concurrently shortened in the SOL presence, hence yielding the KD value of 0.55 μM based on minimal reaction scheme. As cells were exposed to SOL, the steady-state activation curve of IK(M) was shifted along the voltage axis to the left with no change in the gating charge of the current. Upon an isosceles-triangular ramp pulse, the hysteretic area of IK(M) was increased by adding SOL. As cells were continually exposed to SOL, further application of acetylcholine (1 μM) failed to modify SOL-stimulated IK(M); however, subsequent addition of thyrotropin releasing hormone (TRH, 1 μM) was able to counteract SOL-induced increase in IK(M) amplitude. In cell-attached single-channel current recordings, bath addition of SOL led to an increase in the activity of M-type K+ (KM) channels with no change in the single channel conductance; the mean open time of the channel became lengthened. In whole-cell current-clamp recordings, the SOL application reduced the firing of action potentials (APs) in GH3 cells; however, either subsequent addition of TRH or linopirdine was able to reverse SOL-mediated decrease in AP firing. In hippocampal mHippoE-14 neurons, the IK(M) was also stimulated by adding SOL. Altogether, findings from this study disclosed for the first time the effectiveness of SOL in interacting with KM channels and hence in stimulating IK(M) in electrically excitable cells, and this noticeable action appears to be independent of its antagonistic activity on the canonical binding to muscarinic receptors expressed in GH3 or mHippoE-14 cells.
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Affiliation(s)
- Hsin-Yen Cho
- Department of Physiology, National Cheng Kung University Medical College, Tainan City 70101, Taiwan; (H.-Y.C.); (T.-H.C.)
| | - Tzu-Hsien Chuang
- Department of Physiology, National Cheng Kung University Medical College, Tainan City 70101, Taiwan; (H.-Y.C.); (T.-H.C.)
| | - Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Medical College, Tainan City 70101, Taiwan; (H.-Y.C.); (T.-H.C.)
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan City 70101, Taiwan
- Correspondence: ; Tel.: +886-6-2353535-5334; Fax: +886-6-2362780
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Malysz J, Petkov GV. Detrusor Smooth Muscle K V7 Channels: Emerging New Regulators of Urinary Bladder Function. Front Physiol 2020; 11:1004. [PMID: 33041840 PMCID: PMC7526500 DOI: 10.3389/fphys.2020.01004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 07/23/2020] [Indexed: 01/21/2023] Open
Abstract
Relaxation and contraction of the urinary bladder smooth muscle, also known as the detrusor smooth muscle (DSM), facilitate the micturition cycle. DSM contractility depends on cell excitability, which is established by the synchronized activity of multiple diverse ion channels. K+ channels, the largest family of channels, control DSM excitability by maintaining the resting membrane potential and shaping the action potentials that cause the phasic contractions. Among the members of the voltage-gated K+ (KV) channel superfamily, KV type 7 (KV7) channels - KV7.1-KV7.5 members encoded by KCNQ1-KCNQ5 genes - have been recently identified as functional regulators in various cell types including vascular, cardiac, and neuronal cells. Their regulatory roles in DSM, however, are just now emerging and remain to be elucidated. To address this gap, our research group has initiated the systematic investigation of human DSM KV7 channels in collaboration with clinical urologists. In this comprehensive review, we summarize the current understanding of DSM Kv7 channels and highlight recent discoveries in the field. We describe KV7 channel expression profiles at the mRNA and protein levels, and further elaborate on functional effects of KV7 channel selective modulators on DSM excitability, contractility, and intracellular Ca2+ dynamics in animal species along with in vivo studies and the limited data on human DSM. Within each topic, we highlight the main observations, current gaps in knowledge, and most pressing questions and concepts in need of resolution. We emphasize the lack of systematic studies on human DSM KV7 channels that are now actively ongoing in our laboratory.
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Affiliation(s)
- John Malysz
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Georgi V. Petkov
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN, United States
- Department of Pharmacology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
- Department of Urology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
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3
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Malysz J, Petkov GV. Urinary bladder smooth muscle ion channels: expression, function, and regulation in health and disease. Am J Physiol Renal Physiol 2020; 319:F257-F283. [PMID: 32628539 PMCID: PMC7473901 DOI: 10.1152/ajprenal.00048.2020] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 06/21/2020] [Accepted: 06/28/2020] [Indexed: 12/17/2022] Open
Abstract
Urinary bladder smooth muscle (UBSM), also known as detrusor smooth muscle, forms the bladder wall and ultimately determines the two main attributes of the organ: urine storage and voiding. The two functions are facilitated by UBSM relaxation and contraction, respectively, which depend on UBSM excitability shaped by multiple ion channels. In this review, we summarize the current understanding of key ion channels establishing and regulating UBSM excitability and contractility. They include excitation-enhancing voltage-gated Ca2+ (Cav) and transient receptor potential channels, excitation-reducing K+ channels, and still poorly understood Cl- channels. Dynamic interplay among UBSM ion channels determines the overall level of Cav channel activity. The net Ca2+ influx via Cav channels increases global intracellular Ca2+ concentration, which subsequently triggers UBSM contractility. Here, for each ion channel type, we describe UBSM tissue/cell expression (mRNA and protein) profiles and their role in regulating excitability and contractility of UBSM in various animal species, including the mouse, rat, and guinea pig, and, most importantly, humans. The currently available data reveal certain interspecies differences, which complicate the translational value of published animal research results to humans. This review highlights recent developments, findings on genetic knockout models, pharmacological data, reports on UBSM ion channel dysfunction in animal bladder disease models, and the very limited human studies currently available. Among all gaps in present-day knowledge, the unknowns on expression and functional roles for ion channels determined directly in human UBSM tissues and cells under both normal and disease conditions remain key hurdles in the field.
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Affiliation(s)
- John Malysz
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Georgi V Petkov
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee
- Department of Pharmacology, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee
- Department of Urology, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee
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4
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van der Horst J, Greenwood IA, Jepps TA. Cyclic AMP-Dependent Regulation of Kv7 Voltage-Gated Potassium Channels. Front Physiol 2020; 11:727. [PMID: 32695022 PMCID: PMC7338754 DOI: 10.3389/fphys.2020.00727] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 06/04/2020] [Indexed: 01/08/2023] Open
Abstract
Voltage-gated Kv7 potassium channels, encoded by KCNQ genes, have major physiological impacts cardiac myocytes, neurons, epithelial cells, and smooth muscle cells. Cyclic adenosine monophosphate (cAMP), a well-known intracellular secondary messenger, can activate numerous downstream effector proteins, generating downstream signaling pathways that regulate many functions in cells. A role for cAMP in ion channel regulation has been established, and recent findings show that cAMP signaling plays a role in Kv7 channel regulation. Although cAMP signaling is recognized to regulate Kv7 channels, the precise molecular mechanism behind the cAMP-dependent regulation of Kv7 channels is complex. This review will summarize recent research findings that support the mechanisms of cAMP-dependent regulation of Kv7 channels.
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Affiliation(s)
- Jennifer van der Horst
- Vascular Biology Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Iain A Greenwood
- Molecular and Clinical Sciences Institute, St. George's University of London, London, United Kingdom
| | - Thomas A Jepps
- Vascular Biology Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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5
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Zhang F, Liu Y, Tang F, Liang B, Chen H, Zhang H, Wang K. Electrophysiological and pharmacological characterization of a novel and potent neuronal Kv7 channel opener SCR2682 for antiepilepsy. FASEB J 2019; 33:9154-9166. [DOI: 10.1096/fj.201802848rr] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Fan Zhang
- The Key Laboratory of Neural and Vascular Biology Ministry of Education The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province Department of Pharmacology Hebei Medical University Shijiazhuang China
| | - Yani Liu
- Department of Pharmacology Qingdao University Qingdao China
| | - Feng Tang
- Medicinal Chemistry, Simcere Pharmaceutical Nanjing China
| | - Bo Liang
- Medicinal Chemistry Shanghai Zhimeng BioPharma Shanghai China
| | - Huanming Chen
- Medicinal Chemistry Shanghai Zhimeng BioPharma Shanghai China
| | - Hailin Zhang
- The Key Laboratory of Neural and Vascular Biology Ministry of Education The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province Department of Pharmacology Hebei Medical University Shijiazhuang China
| | - Kewei Wang
- Department of Pharmacology Qingdao University Qingdao China
- Institute of Innovative Drugs School of Pharmacy Qingdao University Qingdao China
- Center for Brain Science and Brain‐Inspired Intelligence Guangzhou China
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Abstract
The highly structurally similar drugs flupirtine and retigabine have been regarded as safe and effective for many years but lately they turned out to exert intolerable side effects. While the twin molecules share the mode of action, both stabilize the open state of voltage-gated potassium channels, the form and severity of adverse effects is different. The analgesic flupirtine caused drug-induced liver injury in rare but fatal cases, whereas prolonged use of the antiepileptic retigabine led to blue tissue discoloration. Because the adverse effects seem unrelated to the mode of action, it is likely, that both drugs that occupied important therapeutic niches, could be replaced. Reasons for the clinically relevant toxicity will be clarified and future substitutes for these drugs presented in this review.
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Lawson K. Pharmacology and clinical applications of flupirtine: Current and future options. World J Pharmacol 2019; 8:1-13. [DOI: 10.5497/wjp.v8.i1.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 11/17/2018] [Accepted: 01/05/2019] [Indexed: 02/06/2023] Open
Abstract
Flupirtine is the first representative in a class of triaminopyridines that exhibits pharmacological properties leading to the suppression of over-excitability of neuronal and non-neuronal cells. Consequently, this drug has been used as a centrally acting analgesic in patients with a range of acute and persistent pain conditions without the adverse effects characteristic of opioids and non-steroidal anti-inflammatory drug and is well tolerated. The pharmacological profile exhibited involves actions on several cellular targets, including Kv7 channels, G-protein-regulated inwardly rectifying K channels and γ-aminobutyric acid type A receptors, but also there is evidence of additional as yet unidentified mechanisms of action involved in the effects of flupirtine. Flupirtine has exhibited effects in a range of cells and tissues related to the locations of these targets. In additional to analgesia, flupirtine has demonstrated pharmacological properties consistent with use as an anticonvulsant, a neuroprotectant, skeletal and smooth muscle relaxant, in treatment of auditory and visual disorders, and treatment of memory and cognitive impairment. Flupirtine is providing important information and clues regarding novel mechanistic approaches to the treatment of a range of clinical conditions involving hyper-excitability of cells. Identification of molecules exhibiting specificity for the pharmacological targets (e.g., Kv7 isoforms) involved in the actions of flupirtine will provide further insight into clinical applications. Whether the broad-spectrum pharmacology of flupirtine or target-specific actions is preferential to gain benefit, especially in complex clinical conditions, requires further investigation. This review will consider recent advancement in understanding of the pharmacological profile and related clinical applications of flupirtine.
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Affiliation(s)
- Kim Lawson
- Department of Biosciences and Chemistry, Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield S1 1WB, United Kingdom
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Tykocki NR, Heppner TJ, Dalsgaard T, Bonev AD, Nelson MT. The K V 7 channel activator retigabine suppresses mouse urinary bladder afferent nerve activity without affecting detrusor smooth muscle K + channel currents. J Physiol 2018; 597:935-950. [PMID: 30536555 DOI: 10.1113/jp277021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 12/06/2018] [Indexed: 01/20/2023] Open
Abstract
KEY POINTS KV 7 channels are a family of voltage-dependent K+ channels expressed in many cell types, which open in response to membrane depolarization to regulate cell excitability. Drugs that target KV 7 channels are used clinically to treat epilepsy. Interestingly, these drugs also cause urinary retention, but it was unclear how. In this study, we focused on two possible mechanisms by which retigabine could cause urinary retention: by decreasing smooth muscle excitability, or by decreasing sensory nerve outflow. Urinary bladder smooth muscle had no measurable KV 7 channel currents. However, the KV 7 channel agonist retigabine nearly abolished sensory nerve outflow from the urinary bladder during bladder filling. We conclude that KV 7 channel activation likely affects urinary bladder function by blocking afferent nerve outflow to the brain, which is key to sensing bladder fullness. ABSTRACT KV 7 channels are voltage-dependent K+ channels that open in response to membrane depolarization to regulate cell excitability. KV 7 activators, such as retigabine, were used to treat epilepsy but caused urinary retention. Using electrophysiological recordings from freshly isolated mouse urinary bladder smooth muscle (UBSM) cells, isometric contractility of bladder strips, and ex vivo measurements of bladder afferent activity, we explored the role of KV 7 channels as regulators of murine urinary bladder function. The KV 7 activator retigabine (10 μM) had no effect on voltage-dependent K+ currents or resting membrane potential of UBSM cells, suggesting that these cells lacked retigabine-sensitive KV 7 channels. The KV 7 inhibitor XE-991 (10 μM) inhibited UBSM K+ currents; the properties of these currents, however, were typical of KV 2 channels and not KV 7 channels. Retigabine inhibited voltage-dependent Ca2+ channel (VDCC) currents and reduced steady-state contractions to 60 mM KCl in bladder strips, suggesting that reduction in VDCC current was sufficient to directly affect UBSM function. To determine if retigabine altered ex vivo bladder sensory outflow, we measured afferent activity during simulated transient contractions (TCs) of the bladder wall. Simulated TCs caused bursts of afferent activity that were nearly abolished by retigabine. The effects of retigabine were blocked by co-incubation with XE-991, suggesting specific activation of KV 7 channels on afferent nerves. These results indicate that retigabine primarily affects urinary bladder function by inhibiting TC generation and afferent nerve activity, which are key to sensing bladder fullness. Any direct inhibition of UBSM contractility is likely to be from non-specific effects on VDCCs and KV 2 channels.
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Affiliation(s)
- Nathan R Tykocki
- Department of Pharmacology, University of Vermont, Burlington, VT, 05405, USA
| | - Thomas J Heppner
- Department of Pharmacology, University of Vermont, Burlington, VT, 05405, USA
| | | | - Adrian D Bonev
- Department of Pharmacology, University of Vermont, Burlington, VT, 05405, USA
| | - Mark T Nelson
- Department of Pharmacology, University of Vermont, Burlington, VT, 05405, USA.,Institute of Cardiovascular Sciences, University of Manchester, Manchester, UK
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Mahapatra C, Brain KL, Manchanda R. A biophysically constrained computational model of the action potential of mouse urinary bladder smooth muscle. PLoS One 2018; 13:e0200712. [PMID: 30048468 PMCID: PMC6061979 DOI: 10.1371/journal.pone.0200712] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 07/02/2018] [Indexed: 11/19/2022] Open
Abstract
Urinary incontinence is associated with enhanced spontaneous phasic contractions of the detrusor smooth muscle (DSM). Although a complete understanding of the etiology of these spontaneous contractions is not yet established, it is suggested that the spontaneously evoked action potentials (sAPs) in DSM cells initiate and modulate the contractions. In order to further our understanding of the ionic mechanisms underlying sAP generation, we present here a biophysically detailed computational model of a single DSM cell. First, we constructed mathematical models for nine ion channels found in DSM cells based on published experimental data: two voltage gated Ca2+ ion channels, an hyperpolarization-activated ion channel, two voltage-gated K+ ion channels, three Ca2+-activated K+ ion channels and a non-specific background leak ion channel. The ion channels' kinetics were characterized in terms of maximal conductances and differential equations based on voltage or calcium-dependent activation and inactivation. All ion channel models were validated by comparing the simulated currents and current-voltage relations with those reported in experimental work. Incorporating these channels, our DSM model is capable of reproducing experimentally recorded spike-type sAPs of varying configurations, ranging from sAPs displaying after-hyperpolarizations to sAPs displaying after-depolarizations. The contributions of the principal ion channels to spike generation and configuration were also investigated as a means of mimicking the effects of selected pharmacological agents on DSM cell excitability. Additionally, the features of propagation of an AP along a length of electrically continuous smooth muscle tissue were investigated. To date, a biophysically detailed computational model does not exist for DSM cells. Our model, constrained heavily by physiological data, provides a powerful tool to investigate the ionic mechanisms underlying the genesis of DSM electrical activity, which can further shed light on certain aspects of urinary bladder function and dysfunction.
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Affiliation(s)
- Chitaranjan Mahapatra
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
| | - Keith L. Brain
- School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, England, United Kingdom
| | - Rohit Manchanda
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
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Lee JD, Lee MH, Yang WK, Wang KL, Lee TH. Differential Expression of Renal Outer Medullary K + Channel and Voltage-gated K + Channel 7.1 in Bladder Urothelium of Patients With Interstitial Cystitis/Painful Bladder Syndrome. Urology 2017; 101:169.e1-169.e5. [DOI: 10.1016/j.urology.2016.11.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 10/04/2016] [Accepted: 11/04/2016] [Indexed: 12/27/2022]
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11
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Apostolova E, Zagorchev P, Kokova V, Peychev L. Retigabine diminishes the effects of acetylcholine, adrenaline and adrenergic agonists on the spontaneous activity of guinea pig smooth muscle strips in vitro. Auton Neurosci 2017; 203:51-57. [PMID: 28041987 DOI: 10.1016/j.autneu.2016.12.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 12/14/2016] [Accepted: 12/16/2016] [Indexed: 01/17/2023]
Abstract
PURPOSE The aim of this study is to evaluate the effect of retigabine on the smooth muscle response to acetylcholine, adrenaline, α-and β-adrenoceptor agonists. METHODS We studied the change in the spontaneous smooth muscle contraction of guinea pig gastric corpus strips before and after 20-min treatment with 2μM retigabine. We also evaluated the effect of retigabine on the smooth muscle response to 10μM acetylcholine, 1 and 10μM adrenaline, 1μM methoxamine, 0.1μM p-iodoclonidine and 10μM isoproterenol. RESULTS We observed a significant reduction in the effects of all studied mediators and agonists when they were added to organ baths in the presence of retigabine. Retigabine diminished the effect of acetylcholine on the spontaneous smooth muscle activity. The effect was fully antagonized by XE-991 (Kv7 channel blocker), which supports our hypothesis about the role of KCNQ channels in the registered changes. The increase in the contraction force after adding of 1μM adrenaline, methoxamine, and 0.1μM p-iodoclonidine was also significantly smaller in presence of retigabine. However, comparing the effect of 10μM adrenaline on the contractility before and after treatment with retigabine, we observed increased contractility when retigabine was present in the organ baths. CONCLUSION A possible explanation for the observed diminished effects of mediators and receptor agonists is that the effect of retigabine on smooth muscle contractility is complex. The membrane hyperpolarization, the interaction between Kv7 channels and adrenoceptors, and the influence on signaling pathways may contribute to the summary smooth muscle response.
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Affiliation(s)
- Elisaveta Apostolova
- Department of Pharmacology and Drug Toxicology, Faculty of Pharmacy, Medical University-Plovdiv, Vasil Aprilov Str. 15A, 4002 Plovdiv, Bulgaria.
| | - Plamen Zagorchev
- Department of Biophysics, Faculty of Pharmacy, Medical University-Plovdiv, Vasil Aprilov Str. 15A, 4002 Plovdiv, Bulgaria
| | - Vesela Kokova
- Department of Pharmacology and Drug Toxicology, Faculty of Pharmacy, Medical University-Plovdiv, Vasil Aprilov Str. 15A, 4002 Plovdiv, Bulgaria
| | - Lyudmil Peychev
- Department of Pharmacology and Drug Toxicology, Faculty of Pharmacy, Medical University-Plovdiv, Vasil Aprilov Str. 15A, 4002 Plovdiv, Bulgaria
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12
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Simonsen U. Novel Aspects of Physiology and Pharmacology Related to the Urogenital Tract. Basic Clin Pharmacol Toxicol 2016; 119 Suppl 3:3-4. [PMID: 27791346 DOI: 10.1111/bcpt.12673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ulf Simonsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.
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13
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KV7 channels in the human detrusor: channel modulator effects and gene and protein expression. Naunyn Schmiedebergs Arch Pharmacol 2016; 390:127-137. [DOI: 10.1007/s00210-016-1312-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 10/11/2016] [Indexed: 12/13/2022]
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14
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Hansen HH, Weikop P, Mikkelsen MD, Rode F, Mikkelsen JD. The pan-Kv7 (KCNQ) Channel Opener Retigabine Inhibits Striatal Excitability by Direct Action on Striatal Neurons In Vivo. Basic Clin Pharmacol Toxicol 2016; 120:46-51. [PMID: 27377794 DOI: 10.1111/bcpt.12636] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 06/30/2016] [Indexed: 11/29/2022]
Abstract
Central Kv7 (KCNQ) channels are voltage-dependent potassium channels composed of different combinations of four Kv7 subunits, being differently expressed in the brain. Notably, striatal dopaminergic neurotransmission is strongly suppressed by systemic administration of the pan-Kv7 channel opener retigabine. The effect of retigabine likely involves the inhibition of the activity in mesencephalic dopaminergic neurons projecting to the striatum, but whether Kv7 channels expressed in the striatum may also play a role is not resolved. We therefore assessed the effect of intrastriatal retigabine administration on striatal neuronal excitability in the rat determined by c-Fos immunoreactivity, a marker of neuronal activation. When retigabine was applied locally in the striatum, this resulted in a marked reduction in the number of c-Fos-positive neurons after a strong excitatory striatal stimulus induced by acute systemic haloperidol administration in the rat. The relative mRNA levels of Kv7 subunits in the rat striatum were found to be Kv7.2 = Kv7.3 = Kv7.5 > >Kv7.4. These data suggest that intrastriatal Kv7 channels play a direct role in regulating striatal excitability in vivo.
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Affiliation(s)
- Henrik H Hansen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Denmark.,NeuroSearch A/S, Ballerup, Denmark
| | - Pia Weikop
- Neuropsychiatric Laboratory, Copenhagen University Hospital, Rigshospitalet, Denmark
| | | | | | - Jens D Mikkelsen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Denmark.,NeuroSearch A/S, Ballerup, Denmark
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15
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Haick JM, Byron KL. Novel treatment strategies for smooth muscle disorders: Targeting Kv7 potassium channels. Pharmacol Ther 2016; 165:14-25. [PMID: 27179745 DOI: 10.1016/j.pharmthera.2016.05.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Smooth muscle cells provide crucial contractile functions in visceral, vascular, and lung tissues. The contractile state of smooth muscle is largely determined by their electrical excitability, which is in turn influenced by the activity of potassium channels. The activity of potassium channels sustains smooth muscle cell membrane hyperpolarization, reducing cellular excitability and thereby promoting smooth muscle relaxation. Research over the past decade has indicated an important role for Kv7 (KCNQ) voltage-gated potassium channels in the regulation of the excitability of smooth muscle cells. Expression of multiple Kv7 channel subtypes has been demonstrated in smooth muscle cells from viscera (gastrointestinal, bladder, myometrial), from the systemic and pulmonary vasculature, and from the airways of the lung, from multiple species, including humans. A number of clinically used drugs, some of which were developed to target Kv7 channels in other tissues, have been found to exert robust effects on smooth muscle Kv7 channels. Functional studies have indicated that Kv7 channel activators and inhibitors have the ability to relax and contact smooth muscle preparations, respectively, suggesting a wide range of novel applications for the pharmacological tool set. This review summarizes recent findings regarding the physiological functions of Kv7 channels in smooth muscle, and highlights potential therapeutic applications based on pharmacological targeting of smooth muscle Kv7 channels throughout the body.
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Affiliation(s)
- Jennifer M Haick
- Department of Molecular Pharmacology & Therapeutics, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Kenneth L Byron
- Department of Molecular Pharmacology & Therapeutics, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA.
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16
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Aizawa N, Wakamatsu D, Kida J, Otsuki T, Saito Y, Matsuya H, Homma Y, Igawa Y. Inhibitory effects of retigabine, a Kv7 channel activator, on mechanosensitive primary bladder afferent activities and nociceptive behaviors in rats. Neurourol Urodyn 2015; 36:280-285. [DOI: 10.1002/nau.22920] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 10/13/2015] [Indexed: 01/25/2023]
Affiliation(s)
- Naoki Aizawa
- Department of Continence Medicine; The University of Tokyo Graduate School of Medicine; Tokyo Japan
| | - Daisuke Wakamatsu
- Discovery Research Laboratories 4; Department of Biology & Pharmacology; ONO Pharmaceutical Co., Ltd.; Osaka Japan
| | - Jun Kida
- Discovery Research Laboratories 4; Department of Biology & Pharmacology; ONO Pharmaceutical Co., Ltd.; Osaka Japan
| | - Takeya Otsuki
- Discovery Research Laboratories 4; Department of Biology & Pharmacology; ONO Pharmaceutical Co., Ltd.; Osaka Japan
| | - Yasuho Saito
- Department of Urology; The University of Tokyo Graduate School of Medicine; Tokyo Japan
| | - Hidekazu Matsuya
- Discovery Research Laboratories 4; Department of Biology & Pharmacology; ONO Pharmaceutical Co., Ltd.; Osaka Japan
| | - Yukio Homma
- Department of Urology; The University of Tokyo Graduate School of Medicine; Tokyo Japan
| | - Yasuhiko Igawa
- Department of Continence Medicine; The University of Tokyo Graduate School of Medicine; Tokyo Japan
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17
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Provence A, Malysz J, Petkov GV. The Novel KV7.2/KV7.3 Channel Opener ICA-069673 Reveals Subtype-Specific Functional Roles in Guinea Pig Detrusor Smooth Muscle Excitability and Contractility. J Pharmacol Exp Ther 2015; 354:290-301. [PMID: 26087697 DOI: 10.1124/jpet.115.225268] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 06/17/2015] [Indexed: 12/20/2022] Open
Abstract
The physiologic roles of voltage-gated KV7 channel subtypes (KV7.1-KV7.5) in detrusor smooth muscle (DSM) are poorly understood. Here, we sought to elucidate the functional roles of KV7.2/KV7.3 channels in guinea pig DSM excitability and contractility using the novel KV7.2/KV7.3 channel activator ICA-069673 [N-(2-chloro-5-pyrimidinyl)-3,4-difluorobenzamide]. We employed a multilevel experimental approach using Western blot analysis, immunocytochemistry, isometric DSM tension recordings, fluorescence Ca(2+) imaging, and perforated whole-cell patch-clamp electrophysiology. Western blot experiments revealed the protein expression of KV7.2 and KV7.3 channel subunits in DSM tissue. In isolated DSM cells, immunocytochemistry with confocal microscopy further confirmed protein expression for KV7.2 and KV7.3 channel subunits, where they localize within the vicinity of the cell membrane. ICA-069673 inhibited spontaneous phasic, pharmacologically induced, and nerve-evoked contractions in DSM isolated strips in a concentration-dependent manner. The inhibitory effects of ICA-069673 on DSM spontaneous phasic and tonic contractions were abolished in the presence of the KV7 channel inhibitor XE991 [10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone dihydrochloride]. Under conditions of elevated extracellular K(+) (60 mM), the effects of ICA-069673 on DSM tonic contractions were significantly attenuated. ICA-069673 decreased the global intracellular Ca(2+) concentration in DSM cells, an effect blocked by the L-type Ca(2+) channel inhibitor nifedipine. ICA-069673 hyperpolarized the membrane potential and inhibited spontaneous action potentials of isolated DSM cells, effects that were blocked in the presence of XE991. In conclusion, using the novel KV7.2/KV7.3 channel activator ICA-069673, this study provides strong evidence for a critical role for the KV7.2- and KV7.3-containing channels in DSM function at both cellular and tissue levels.
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Affiliation(s)
- Aaron Provence
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina
| | - John Malysz
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina
| | - Georgi V Petkov
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina
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18
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Svalø J, Sheykhzade M, Nordling J, Matras C, Bouchelouche P. Functional and molecular evidence for Kv7 channel subtypes in human detrusor from patients with and without bladder outflow obstruction. PLoS One 2015; 10:e0117350. [PMID: 25692982 PMCID: PMC4333569 DOI: 10.1371/journal.pone.0117350] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 12/21/2014] [Indexed: 12/30/2022] Open
Abstract
The aim of the study was to investigate whether Kv7 channels and their ancillary β-subunits, KCNE, are functionally expressed in the human urinary bladder. Kv7 channels were examined at the molecular level and by functional studies using RT-qPCR and myography, respectively. We found mRNA expression of KCNQ1, KCNQ3-KCNQ5 and KCNE1-5 in the human urinary bladder from patients with normal bladder function (n = 7) and in patients with bladder outflow obstruction (n = 3). Interestingly, a 3.4-fold up-regulation of KCNQ1 was observed in the latter. The Kv7 channel subtype selective modulators, ML277 (activator of Kv7.1 channels, 10 μM) and ML213 (activator of Kv7.2, Kv7.4, Kv7.4/7.5 and Kv7.5 channels, 10 μM), reduced the tone of 1 μM carbachol pre-constricted bladder strips. XE991 (blocker of Kv7.1-7.5 channels, 10 μM) had opposing effects as it increased contractions achieved with 20 mM KPSS. Furthermore, we investigated if there is interplay between Kv7 channels and β-adrenoceptors. Using cumulative additions of isoprenaline (β-adrenoceptor agonist) and forskolin (adenylyl cyclase activator) in combination with the Kv7 channel activator and blocker, retigabine and XE991, we did not find interplay between Kv7 channels and β-adrenoceptors in the human urinary bladder. The performed gene expression analysis combined with the organ bath studies imply that compounds that activate Kv7 channels could be useful for treatment of overactive bladder syndrome.
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Affiliation(s)
- Julie Svalø
- Smooth Muscle Research Center, Department of Clinical Biochemistry, Copenhagen University Hospital, Koege, Denmark
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- * E-mail:
| | - Majid Sheykhzade
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Jørgen Nordling
- Department of Urology, Copenhagen University Hospital, Herlev, Denmark
| | - Christina Matras
- Department of Urology, Copenhagen University Hospital, Naestved, Denmark
| | - Pierre Bouchelouche
- Smooth Muscle Research Center, Department of Clinical Biochemistry, Copenhagen University Hospital, Koege, Denmark
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19
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Anderson UA, Carson C, Johnston L, Joshi S, Gurney AM, McCloskey KD. Functional expression of KCNQ (Kv7) channels in guinea pig bladder smooth muscle and their contribution to spontaneous activity. Br J Pharmacol 2014; 169:1290-304. [PMID: 23586426 PMCID: PMC3746117 DOI: 10.1111/bph.12210] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 03/15/2013] [Accepted: 03/26/2013] [Indexed: 12/30/2022] Open
Abstract
Background and Purpose The aim of the study was to determine whether KCNQ channels are functionally expressed in bladder smooth muscle cells (SMC) and to investigate their physiological significance in bladder contractility. Experimental Approach KCNQ channels were examined at the genetic, protein, cellular and tissue level in guinea pig bladder smooth muscle using RT-PCR, immunofluorescence, patch-clamp electrophysiology, calcium imaging, detrusor strip myography, and a panel of KCNQ activators and inhibitors. Key Results KCNQ subtypes 1–5 are expressed in bladder detrusor smooth muscle. Detrusor strips typically displayed TTX-insensitive myogenic spontaneous contractions that were increased in amplitude by the KCNQ channel inhibitors XE991, linopirdine or chromanol 293B. Contractility was inhibited by the KCNQ channel activators flupirtine or meclofenamic acid (MFA). The frequency of Ca2+-oscillations in SMC contained within bladder tissue sheets was increased by XE991. Outward currents in dispersed bladder SMC, recorded under conditions where BK and KATP currents were minimal, were significantly reduced by XE991, linopirdine, or chromanol, and enhanced by flupirtine or MFA. XE991 depolarized the cell membrane and could evoke transient depolarizations in quiescent cells. Flupirtine (20 μM) hyperpolarized the cell membrane with a simultaneous cessation of any spontaneous electrical activity. Conclusions and Implications These novel findings reveal the role of KCNQ currents in the regulation of the resting membrane potential of detrusor SMC and their important physiological function in the control of spontaneous contractility in the guinea pig bladder.
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Affiliation(s)
- U A Anderson
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, UK
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20
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Jepps TA, Bentzen BH, Stott JB, Povstyan OV, Sivaloganathan K, Dalby-Brown W, Greenwood IA. Vasorelaxant effects of novel Kv 7.4 channel enhancers ML213 and NS15370. Br J Pharmacol 2014; 171:4413-24. [PMID: 24909207 DOI: 10.1111/bph.12805] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 04/25/2014] [Accepted: 05/14/2014] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE The KCNQ-encoded voltage-gated potassium channel family (Kv 7.1-Kv 7.5) are established regulators of smooth muscle contractility, where Kv 7.4 and Kv 7.5 predominate. Various Kv 7.2-7.5 channel enhancers have been developed that have been shown to cause a vasorelaxation in both rodent and human blood vessels. Recently, two novel Kv 7 channel enhancers have been identified, ML213 and NS15370, that show increased potency, particularly on Kv 7.4 channels. The aim of this study was to characterize the effects of these novel enhancers in different rat blood vessels and compare them with Kv 7 enhancers (S-1, BMS204352, retigabine) described previously. We also sought to determine the binding sites of the new Kv 7 enhancers. KEY RESULTS Both ML213 and NS15370 relaxed segments of rat thoracic aorta, renal artery and mesenteric artery in a concentration-dependent manner. In the mesenteric artery ML213 and NS15370 displayed EC50 s that were far lower than other Kv 7 enhancers tested. Current-clamp experiments revealed that both novel enhancers, at low concentrations, caused significant hyperpolarization in mesenteric artery smooth muscle cells. In addition, we determined that the stimulatory effect of these enhancers relied on a tryptophan residue located in the S5 domain, which is the same binding site for the other Kv 7 enhancers tested in this study. CONCLUSIONS AND IMPLICATIONS This study has identified and characterized ML213 and NS15370 as potent vasorelaxants in different blood vessels, thereby highlighting these new compounds as potential therapeutics for various smooth muscle disorders.
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Affiliation(s)
- T A Jepps
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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21
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Wang Y, Tar MT, Fu S, Melman A, Davies KP. Diabetes attenuates urothelial modulation of detrusor contractility and spontaneous activity. Int J Urol 2014; 21:1059-64. [PMID: 24846346 DOI: 10.1111/iju.12491] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 04/13/2014] [Indexed: 02/04/2023]
Abstract
OBJECTIVES To investigate the effect of diabetes on urothelial modulation of bladder contractility. METHODS Bladder strips (urothelium intact or denuded) were prepared from 8-week-old streptozotocin-induced diabetic (n = 19) and non-diabetic control rats (n = 10). The effect of modulators of MaxiK (iberiotoxin and tetraethylammonium) and Kv7 (XE991 and retigabine) potassium channel activity were investigated for their effects on both carbachol-induced force generation and spontaneous contractile activity. RESULTS In bladder strips from non-diabetic animals, the presence of the urothelium resulted in marked sensitivity to carbachol-induced force generation by modulators of MaxiK and Kv7 channel activity, whereas in the diabetic animal urothelial sensitivity to these agents was significantly diminished. Urothelial-intact bladder strips from non-diabetic animals were more sensitive to modulators of Kv7 activity in reducing the amplitude of spontaneous phasic contractions than urothelial-denuded bladder strips, whereas in diabetic animals the presence or absence of the urothelium did not alter the sensitivity to modulators of Kv7 activity. Spontaneous activity in the presence of tetraethylammonium was not affected by the urothelium in bladder strips from either diabetic or non-diabetic animals. CONCLUSIONS The presence of the urothelium in bladders from non-diabetic animals modulates the activity of potassium blockers to affect bladder contractility, whereas in the diabetic bladder this effect is attenuated. These findings could help to explain the lack of success of pharmaceutical treatments targeting potassium channels to treat bladder pathology in patients with diseases imparing urothelial function.
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Affiliation(s)
- Yi Wang
- Department of Urology, Albert Einstein College of Medicine, Bronx, New York, USA
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22
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Jepps TA, Olesen SP, Greenwood IA. One man's side effect is another man's therapeutic opportunity: targeting Kv7 channels in smooth muscle disorders. Br J Pharmacol 2014; 168:19-27. [PMID: 22880633 DOI: 10.1111/j.1476-5381.2012.02133.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Retigabine is a first in class anticonvulsant that has recently undergone clinical trials to test its efficacy in epileptic patients. Retigabine's novel mechanism of action - activating Kv7 channels - suppresses neuronal activity to prevent seizure generation by hyperpolarizing the membrane potential and suppressing depolarizing surges. However, Kv7 channels are not expressed exclusively in neurones and data generated over the last decade have shown that Kv7 channels play a key role in various smooth muscle systems of the body. This review discusses the potential of targeting Kv7 channels in the smooth muscle to treat diseases such as hypertension, bladder instability, constipation and preterm labour.
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Affiliation(s)
- T A Jepps
- Division of Biomedical Sciences, St George's, University of London, Cranmer Terrace, UK
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23
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Adduci A, Martire M, Taglialatela M, Arena V, Rizzo G, Coco C, Currò D. Expression and motor functional roles of voltage-dependent type 7 K(+) channels in the human taenia coli. Eur J Pharmacol 2013; 721:12-20. [PMID: 24120659 DOI: 10.1016/j.ejphar.2013.09.061] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 09/05/2013] [Accepted: 09/20/2013] [Indexed: 02/07/2023]
Abstract
Voltage-dependent type 7 K(+) (KV7 or KCNQ) channels modulate the excitability of neurons and muscle cells. The aims of the present study were to investigate the motor effects of KV7 channel modulators and the expression of KV7 channels in the human taenia coli. The effects of KV7 channel modulators on the muscle tone of human taenia coli strips were investigated under nonadrenergic non-nitrergic conditions by organ bath studies. Gene expression and tissue localisation of channels were studied by real-time PCR and immunohistochemistry, respectively. Under basal conditions, the KV7 channel blocker XE-991 induced concentration-dependent contractions, with mean EC50 and Emax of 18.7 μM and 30.5% respectively of the maximal bethanechol-induced contraction, respectively. The KV7 channel activators retigabine and flupirtine concentration-dependently relaxed the taenia coli, with mean EC50s of 19.2 μM and 29.9 μM, respectively. Retigabine also relaxed bethanechol-precontracted strips, with maximal relaxations of 79.2% of the bethanecol-induced precontraction. The motor effects induced by the KV7 channel modulators were not affected by tetrodotoxin or ω-conotoxin GVIA. XE-991 greatly reduced retigabine- and flupirtine-induced relaxations. Transcripts encoded by all KCNQ genes were detected in the taenia coli, with KCNQ4 showing the highest expression levels. KV7.4 channels were clearly visualised by immunohistochemistry in colonic epithelium, circular muscle layer and taenia coli. KV7 channels appear to contribute to the resting muscle tone of the human taenia coli. In addition, KV7 channel activators significantly relax the taenia coli. Thus, they could be useful therapeutic relaxant agents for colonic motor disorders.
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Affiliation(s)
- Alice Adduci
- Institute of Pharmacology, School of Medicine, Catholic University of the Sacred Heart, L.go F. Vito 1, 00168 Rome, Italy
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24
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Afeli SAY, Malysz J, Petkov GV. Molecular expression and pharmacological evidence for a functional role of kv7 channel subtypes in Guinea pig urinary bladder smooth muscle. PLoS One 2013; 8:e75875. [PMID: 24073284 PMCID: PMC3779188 DOI: 10.1371/journal.pone.0075875] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 08/19/2013] [Indexed: 12/30/2022] Open
Abstract
Voltage-gated Kv7 (KCNQ) channels are emerging as essential regulators of smooth muscle excitability and contractility. However, their physiological role in detrusor smooth muscle (DSM) remains to be elucidated. Here, we explored the molecular expression and function of Kv7 channel subtypes in guinea pig DSM by RT-PCR, qRT-PCR, immunohistochemistry, electrophysiology, and isometric tension recordings. In whole DSM tissue, mRNAs for all Kv7 channel subtypes were detected in a rank order: Kv7.1~Kv7.2Kv7.3~Kv7.5Kv7.4. In contrast, freshly-isolated DSM cells showed mRNA expression of: Kv7.1~Kv7.2Kv7.5Kv7.3~Kv7.4. Immunohistochemical confocal microscopy analyses of DSM, conducted by using co-labeling of Kv7 channel subtype-specific antibodies and α-smooth muscle actin, detected protein expression for all Kv7 channel subtypes, except for the Kv7.4, in DSM cells. L-364373 (R-L3), a Kv7.1 channel activator, and retigabine, a Kv7.2-7.5 channel activator, inhibited spontaneous phasic contractions and the 10-Hz electrical field stimulation (EFS)-induced contractions of DSM isolated strips. Linopiridine and XE991, two pan-Kv7 (effective at Kv7.1-Kv7.5 subtypes) channel inhibitors, had opposite effects increasing DSM spontaneous phasic and 10 Hz EFS-induced contractions. EFS-induced DSM contractions generated by a wide range of stimulation frequencies were decreased by L-364373 (10 µM) or retigabine (10 µM), and increased by XE991 (10 µM). Retigabine (10 µM) induced hyperpolarization and inhibited spontaneous action potentials in freshly-isolated DSM cells. In summary, Kv7 channel subtypes are expressed at mRNA and protein levels in guinea pig DSM cells. Their pharmacological modulation can control DSM contractility and excitability; therefore, Kv7 channel subtypes provide potential novel therapeutic targets for urinary bladder dysfunction.
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Affiliation(s)
- Serge A. Y. Afeli
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina, United States of America
| | - John Malysz
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina, United States of America
| | - Georgi V. Petkov
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina, United States of America
- * E-mail:
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25
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Shvarts GY, Shvarts PG, Plotnikov AN, Savvin DY. Drugs for the treatment of overactive bladder syndrome: present and future (A Review). Pharm Chem J 2013. [DOI: 10.1007/s11094-013-0873-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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