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Hwang EM, Lee BH, Byun EH, Lee S, Kang D, Lee DK, Song MS, Hong SG. Monitoring trafficking and expression of hemagglutinin-tagged transient receptor potential melastatin 4 channel in mammalian cells. Korean J Physiol Pharmacol 2023; 27:417-426. [PMID: 37394239 DOI: 10.4196/kjpp.2023.27.4.417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 06/05/2023] [Accepted: 06/05/2023] [Indexed: 07/04/2023]
Abstract
The TRPM4 gene encodes a Ca2+-activated monovalent cation channel called transient receptor potential melastatin 4 (TRPM4) that is expressed in various tissues. Dysregulation or abnormal expression of TRPM4 has been linked to a range of diseases. We introduced the hemagglutinin (HA) tag into the extracellular S6 loop of TRPM4, resulting in an HA-tagged version called TRPM4-HA. This TRPM4-HA was developed to investigate the purification, localization, and function of TRPM4 in different physiological and pathological conditions. TRPM4-HA was successfully expressed in the intact cell membrane and exhibited similar electrophysiological properties, such as the current-voltage relationship, rapid desensitization, and current size, compared to the wild-type TRPM4. The presence of the TRPM4 inhibitor 9-phenanthrol did not affect these properties. Furthermore, a wound-healing assay showed that TRPM4-HA induced cell proliferation and migration, similar to the native TRPM4. Co-expression of protein tyrosine phosphatase, non-receptor type 6 (PTPN6 or SHP-1) with TRPM4-HA led to the translocation of TRPM4-HA to the cytosol. To investigate the interaction between PTPN6 and tyrosine residues of TRPM4 in enhancing channel activity, we generated four mutants in which tyrosine (Y) residues were substituted with phenylalanine (F) at the N-terminus of TRPM4. The YF mutants displayed properties and functions similar to TRPM4-HA, except for the Y256F mutant, which showed resistance to 9-phenanthrol, suggesting that Y256 may be involved in the binding site for 9-phenanthrol. Overall, the creation of HA-tagged TRPM4 provides researchers with a valuable tool to study the role of TRPM4 in different conditions and its potential interactions with other proteins, such as PTPN6.
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Affiliation(s)
- Eun Mi Hwang
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Bo Hyun Lee
- Department of Physiology, College of Medicine, Gyeongsang National University, Jinju 52727, Korea
| | - Eun Hye Byun
- Department of Physiology, College of Medicine, Gyeongsang National University, Jinju 52727, Korea
| | - Soomin Lee
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Dawon Kang
- Department of Physiology, College of Medicine, Gyeongsang National University, Jinju 52727, Korea
| | - Dong Kun Lee
- Department of Physiology, College of Medicine, Gyeongsang National University, Jinju 52727, Korea
| | - Min Seok Song
- Department of Physiology, College of Medicine, Gyeongsang National University, Jinju 52727, Korea
| | - Seong-Geun Hong
- Department of Physiology, College of Medicine, Gyeongsang National University, Jinju 52727, Korea
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Pimpjong K, Matsuyama H, Mizutani T, Tanahashi Y, Ohta T, Unno T. Possible role of transient receptor potential melastatin 4 channels in adrenergic contractions in mouse prostate smooth muscles. J Vet Med Sci 2023:23-0112. [PMID: 37225446 PMCID: PMC10372249 DOI: 10.1292/jvms.23-0112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023] Open
Abstract
Transient receptor potential melastatin 4 (TRPM4) cation channels are expressed in prostate glands. However, the precise role of these channels in prostate contractility remains unclear. In this study, we examined whether TRPM4 channels were involved in adrenergic contractions in the mouse prostate gland. Adrenergic contractile responses elicited by noradrenaline or electrical field stimulation of the sympathetic nerve were isometrically recorded, and the effects of 9-phenanthrol, a specific TRPM4 channel inhibitor, on those contractile responses were investigated in mouse ventral prostate preparations. 9-phenanthrol (10 or 30 μM) inhibited noradrenaline- and sympathetic nerve-evoked contractions in a concentration-dependent manner. A similar inhibitory effect was observed with another TRPM4 channel inhibitor, 4-chloro-2-(2-(naphthalene-1-yloxy) acetamido) benzoic acid (NBA; 10 μM). Inhibition by 9-phenanthrol and NBA were much greater at lower noradrenaline concentrations and lower stimulus frequencies than those of higher concentrations or frequencies. However, 9-phenanthrol did not inhibit the noradrenaline-induced contractile response when the membrane potential was decreased to approximately 0 mV in the 140 mM K+ medium. Moreover, 9-phenanthrol does not affect noradrenaline-induced increases in spontaneous contractions of cardiac atrial preparation. This agent inhibited noradrenaline-induced contractions in the posterior aorta preparation. However, the inhibitory effect was significantly weaker than that observed in the prostate gland. These results suggest that TRPM4 channels are involved in adrenergic contractions in the mouse prostate gland, possibly by opening through membrane depolarization; therefore, they might be potential candidates for treating benign prostatic hyperplasia.
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Affiliation(s)
- Kiattisak Pimpjong
- Department of Basic Veterinary Science, Joint Graduate School of Veterinary Science, Gifu University
| | - Hayato Matsuyama
- Department of Basic Veterinary Science, Joint Graduate School of Veterinary Science, Gifu University
- Laboratory of Veterinary Pharmacology, Joint Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University
| | - Taichi Mizutani
- Laboratory of Veterinary Pharmacology, Joint Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University
| | - Yasuyuki Tanahashi
- Department of Frontier Life Sciences, Faculty of Life Sciences, Kyoto Sangyo University
| | - Toshio Ohta
- Department of Basic Veterinary Science, Joint Graduate School of Veterinary Science, Tottori University
| | - Toshihiro Unno
- Department of Basic Veterinary Science, Joint Graduate School of Veterinary Science, Gifu University
- Laboratory of Veterinary Pharmacology, Joint Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University
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Ma P, Huang N, Tang J, Zhou Z, Xu J, Chen Y, Zhang M, Huang Q, Cheng Y. The TRPM4 channel inhibitor 9-phenanthrol alleviates cerebral edema after traumatic brain injury in rats. Front Pharmacol 2023; 14:1098228. [PMID: 36865920 PMCID: PMC9971592 DOI: 10.3389/fphar.2023.1098228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 02/03/2023] [Indexed: 02/16/2023] Open
Abstract
Cerebral edema (CE) exerts an important effect on brain injury after traumatic brain injury (TBI). Upregulation of transient receptor potential melastatin 4 (TRPM4) in vascular endothelial cells (ECs) results in damage to capillaries and the blood-brain barrier (BBB), which is critical for the development of CE. Many studies have shown that 9-phenanthrol (9-PH) effectively inhibits TRPM4. The current study aimed to investigate the effect of 9-PH on reducing CE after TBI. In this experiment, we observed that 9-PH markedly reduced brain water content, BBB disruption, proliferation of microglia and astrocytes, neutrophil infiltration, neuronal apoptosis and neurobehavioral deficits. At the molecular level, 9-PH significantly inhibited the protein expression of TRPM4 and MMP-9, alleviated the expression of apoptosis-related molecules and inflammatory cytokines, such as Bax, TNF-α and IL-6, near injured tissue, and diminished serum SUR1 and TRPM4 levels. Mechanistically, treatment with 9-PH inhibited activation of the PI3K/AKT/NF-kB signaling pathway, which was reported to be involved in the expression of MMP-9. Taken together, the results of this study indicate that 9-PH effectively reduces CE and alleviates secondary brain injury partly through the following possible mechanisms: ①9-PH inhibits TRPM4-mediated Na + influx and reduces cytotoxic CE; ②9-PH hinders the expression and activity of MMP-9 by inhibiting the TRPM4 channel and decreases disruption of the BBB, thereby preventing vasogenic cerebral edema. ③9-PH reduces further inflammatory and apoptotic damage to tissues.
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Affiliation(s)
- Ping Ma
- Department of Neurosurgery, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Ning Huang
- Department of Neurosurgery, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Jun Tang
- Department of Neurosurgery, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Zunjie Zhou
- Department of Neurosurgery, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Jing Xu
- Department of Neurosurgery, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Yi Chen
- Department of Rehabilitation, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Maoxin Zhang
- Department of Neurosurgery, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Qin Huang
- Department of Neurosurgery, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China,*Correspondence: Qin Huang, ; Yuan Cheng,
| | - Yuan Cheng
- Department of Neurosurgery, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China,*Correspondence: Qin Huang, ; Yuan Cheng,
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Arullampalam P, Preti B, Ross-Kaschitza D, Lochner M, Rougier JS, Abriel H. Species-Specific Effects of Cation Channel TRPM4 Small-Molecule Inhibitors. Front Pharmacol 2021; 12:712354. [PMID: 34335274 PMCID: PMC8321095 DOI: 10.3389/fphar.2021.712354] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 06/30/2021] [Indexed: 12/14/2022] Open
Abstract
Background: The Transient Receptor Potential Melastatin member 4 (TRPM4) gene encodes a calcium-activated non-selective cation channel expressed in several tissues. Mutations in TRPM4 have been reported in patients with different types of cardiac conduction defects. It is also linked to immune response and cancers, but the associated molecular mechanisms are still unclear. Thus far, 9-phenanthrol is the most common pharmacological compound used to investigate TRPM4 function. We recently identified two promising aryloxyacyl-anthranilic acid compounds (abbreviated CBA and NBA) inhibiting TRPM4. However, all aforementioned compounds were screened using assays expressing human TRPM4, whereas the efficacy of mouse TRPM4 has not been assessed. Mouse models are essential to investigate ion channel physiology and chemical compound efficacy. Aim: In this study, we performed comparative electrophysiology experiments to assess the effect of these TRPM4 inhibitors on human and mouse TRPM4 channels heterologously expressed in TsA-201 cells. Methods and Results: We identified striking species-dependent differences in TRPM4 responses. NBA inhibited both human and mouse TRPM4 currents when applied intracellularly and extracellularly using excised membrane patches. CBA inhibited human TRPM4, both intracellularly and extracellularly. Unexpectedly, the application of CBA had no inhibiting effect on mouse TRPM4 current when perfused on the extracellular side. Instead, its increased mouse TRPM4 current at negative holding potentials. In addition, CBA on the intracellular side altered the outward rectification component of the mouse TRPM4 current. Application of 9-phenanthrol, both intracellularly and extracellularly, inhibited human TRPM4. For mouse TRPM4, 9-phenanthrol perfusion led to opposite effects depending on the site of application. With intracellular 9-phenanthrol, we observed a tendency towards potentiation of mouse TRPM4 outward current at positive holding potentials. Conclusion: Altogether, these results suggest that pharmacological compounds screened using “humanised assays” should be extensively characterised before application in vivo mouse models.
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Affiliation(s)
- Prakash Arullampalam
- Swiss National Centre of Competence in Research (NCCR) TransCure, Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Barbara Preti
- Swiss National Centre of Competence in Research (NCCR) TransCure, Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Daniela Ross-Kaschitza
- Swiss National Centre of Competence in Research (NCCR) TransCure, Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Martin Lochner
- Swiss National Centre of Competence in Research (NCCR) TransCure, Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Jean-Sébastien Rougier
- Swiss National Centre of Competence in Research (NCCR) TransCure, Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Hugues Abriel
- Swiss National Centre of Competence in Research (NCCR) TransCure, Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
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Veress R, Baranyai D, Hegyi B, Kistamás K, Dienes C, Magyar J, Bányász T, Nánási PP, Szentandrássy N, Horváth B. Transient receptor potential melastatin 4 channel inhibitor 9-phenanthrol inhibits K + but not Ca 2+ currents in canine ventricular myocytes. Can J Physiol Pharmacol 2018; 96:1022-1029. [PMID: 29806985 DOI: 10.1139/cjpp-2018-0049] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The role of transient receptor potential melastatin 4 (TRPM4) channels has been frequently tested using their inhibitor 9-phenanthrol in various cardiac preparations; however, the selectivity of the compound is uncertain. Therefore, in the present study, the concentration-dependent effects of 9-phenanthrol on major ionic currents were studied in canine isolated ventricular cells using whole-cell configuration of the patch-clamp technique and 10 mM BAPTA-containing pipette solution to prevent the Ca2+-dependent activation of TRPM4 channels. Transient outward (Ito1), rapid delayed rectifier (IKr), and inward rectifier (IK1) K+ currents were suppressed by 10 and 30 μM 9-phenanthrol with the blocking potency for IK1 < IKr < Ito1 and partial reversibility. L-type Ca2+ current was not affected up to the concentration of 30 μM. In addition, a steady outward current was detected at voltages positive to -40 mV in 9-phenanthrol, which was larger at more positive voltages and larger 9-phenanthrol concentrations. Action potentials were recorded using microelectrodes. Maximal rate of depolarization, phase-1 repolarization, and terminal repolarization were decreased and the plateau potential was depressed by 9-phenanthrol (3-30 μM), congruently with the observed alterations of ionic currents. Significant action potential prolongation was observed by 9-phenanthrol in the majority of the studied cells, but only at 30 μM concentration. In conclusion, 9-phenanthrol is not selective to TRPM4 channels in canine ventricular myocardium; therefore, its application as a TRPM4 blocker can be appropriate only in expression systems but not in native cardiac cells.
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Affiliation(s)
- Roland Veress
- a Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Dóra Baranyai
- a Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Bence Hegyi
- b Department of Pharmacology, University of California at Davis, Davis, CA 95616, USA
| | - Kornél Kistamás
- a Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Csaba Dienes
- a Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - János Magyar
- a Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,c Division of Sport Physiology, Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Tamás Bányász
- a Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Péter P Nánási
- a Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,d Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Norbert Szentandrássy
- a Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,d Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Balázs Horváth
- a Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,e Faculty of Pharmacy, University of Debrecen, Debrecen, Hungary
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Hristov KL, Smith AC, Parajuli SP, Malysz J, Rovner ES, Petkov GV. Novel regulatory mechanism in human urinary bladder: central role of transient receptor potential melastatin 4 channels in detrusor smooth muscle function. Am J Physiol Cell Physiol 2016; 310:C600-11. [PMID: 26791488 DOI: 10.1152/ajpcell.00270.2015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 01/13/2016] [Indexed: 11/22/2022]
Abstract
Transient receptor potential melastatin 4 (TRPM4) channels are Ca(2+)-activated nonselective cation channels that have been recently identified as regulators of detrusor smooth muscle (DSM) function in rodents. However, their expression and function in human DSM remain unexplored. We provide insights into the functional role of TRPM4 channels in human DSM under physiological conditions. We used a multidisciplinary experimental approach, including RT-PCR, Western blotting, immunohistochemistry and immunocytochemistry, patch-clamp electrophysiology, and functional studies of DSM contractility. DSM samples were obtained from patients without preoperative overactive bladder symptoms. RT-PCR detected mRNA transcripts for TRPM4 channels in human DSM whole tissue and freshly isolated single cells. Western blotting and immunohistochemistry with confocal microscopy revealed TRPM4 protein expression in human DSM. Immunocytochemistry further detected TRPM4 protein expression in DSM single cells. Patch-clamp experiments showed that 9-phenanthrol, a selective TRPM4 channel inhibitor, significantly decreased the transient inward cation currents and voltage step-induced whole cell currents in freshly isolated human DSM cells. In current-clamp mode, 9-phenanthrol hyperpolarized the human DSM cell membrane potential. Furthermore, 9-phenanthrol attenuated the spontaneous phasic, carbachol-induced and nerve-evoked contractions in human DSM isolated strips. Significant species-related differences in TRPM4 channel activity between human, rat, and guinea pig DSM were revealed, suggesting a more prominent physiological role for the TRPM4 channel in the regulation of DSM function in humans than in rodents. In conclusion, TRPM4 channels regulate human DSM excitability and contractility and are critical determinants of human urinary bladder function. Thus, TRPM4 channels could represent promising novel targets for the pharmacological or genetic control of overactive bladder.
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Affiliation(s)
- Kiril L Hristov
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina; and
| | - Amy C Smith
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina; and
| | - Shankar P Parajuli
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina; and
| | - John Malysz
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina; and
| | - Eric S Rovner
- Medical University of South Carolina, Charleston, South Carolina
| | - Georgi V Petkov
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina; and Medical University of South Carolina, Charleston, South Carolina
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Guinamard R, Hof T, Del Negro CA. The TRPM4 channel inhibitor 9-phenanthrol. Br J Pharmacol 2014; 171:1600-13. [PMID: 24433510 PMCID: PMC3966741 DOI: 10.1111/bph.12582] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 12/17/2013] [Accepted: 01/08/2014] [Indexed: 01/06/2023] Open
Abstract
The phenanthrene-derivative 9-phenanthrol is a recently identified inhibitor of the transient receptor potential melastatin (TRPM) 4 channel, a Ca(2+) -activated non-selective cation channel whose mechanism of action remains to be determined. Subsequent studies performed on other ion channels confirm the specificity of the drug for TRPM4. In addition, 9-phenanthrol modulates a variety of physiological processes through TRPM4 current inhibition and thus exerts beneficial effects in several pathological conditions. 9-Phenanthrol modulates smooth muscle contraction in bladder and cerebral arteries, affects spontaneous activity in neurons and in the heart, and reduces lipopolysaccharide-induced cell death. Among promising potential applications, 9-phenanthrol exerts cardioprotective effects against ischaemia-reperfusion injuries and reduces ischaemic stroke injuries. In addition to reviewing the biophysical effects of 9-phenanthrol, here we present information about its appropriate use in physiological studies and possible clinical applications.
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Affiliation(s)
- R Guinamard
- EA 4650, Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, UCBN, Normandie UniversitéCaen, France
- Department of Applied Science, The College of William and MaryWilliamsburg, VA, USA
| | - T Hof
- EA 4650, Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, UCBN, Normandie UniversitéCaen, France
| | - C A Del Negro
- Department of Applied Science, The College of William and MaryWilliamsburg, VA, USA
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Parajuli SP, Hristov KL, Sullivan MN, Xin W, Smith AC, Earley S, Malysz J, Petkov GV. Control of urinary bladder smooth muscle excitability by the TRPM4 channel modulator 9-phenanthrol. Channels (Austin) 2013; 7:537-40. [PMID: 24037125 DOI: 10.4161/chan.26289] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The Ca (2+)-activated monovalent cation selective transient receptor potential melastatin 4 (TRPM4) channel has been recently identified in detrusor smooth muscle (DSM) of the urinary bladder. Two recent publications by our research group provide evidence in support of the novel hypothesis that TRPM4 channels enhance DSM excitability and contractility. This is a critical question as prior studies have primarily targeted hyperpolarizing currents facilitated by K(+) channels, but the depolarizing component in DSM cells is not well understood. For the first time, we utilized the selective TRPM4 channel inhibitor, 9-phenanthrol, to investigate TRPM4 channel functional effects in DSM at both cellular and tissue levels in rodents. Our new data presented here showed that in rat DSM cells, 9-phenanthrol attenuates spontaneous inward currents in the presence of the muscarinic receptor agonist, carbachol, thus reducing DSM cell excitability. In support of our original hypothesis, we found that TRPM4 channel mRNA levels are much higher in DSM vs. vascular smooth muscle and that inhibition of TRPM4 channels can potentially attenuate DSM excitability. Thus, we postulate the novel concept that selective pharmacological inhibition of TRPM4 channels can limit both excitability and contractility of DSM.
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Affiliation(s)
- Shankar P Parajuli
- Department of Drug Discovery and Biomedical Sciences; South Carolina College of Pharmacy; University of South Carolina; Columbia, SC USA
| | - Kiril L Hristov
- Department of Drug Discovery and Biomedical Sciences; South Carolina College of Pharmacy; University of South Carolina; Columbia, SC USA
| | - Michelle N Sullivan
- Vascular Physiology Research Group; Department of Biomedical Sciences; Colorado State University; Fort Collins, CO USA
| | - Wenkuan Xin
- Department of Drug Discovery and Biomedical Sciences; South Carolina College of Pharmacy; University of South Carolina; Columbia, SC USA
| | - Amy C Smith
- Department of Drug Discovery and Biomedical Sciences; South Carolina College of Pharmacy; University of South Carolina; Columbia, SC USA
| | - Scott Earley
- Vascular Physiology Research Group; Department of Biomedical Sciences; Colorado State University; Fort Collins, CO USA
| | - John Malysz
- Department of Drug Discovery and Biomedical Sciences; South Carolina College of Pharmacy; University of South Carolina; Columbia, SC USA
| | - Georgi V Petkov
- Department of Drug Discovery and Biomedical Sciences; South Carolina College of Pharmacy; University of South Carolina; Columbia, SC USA
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