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Monastyrnaya MM, Kalina RS, Kozlovskaya EP. The Sea Anemone Neurotoxins Modulating Sodium Channels: An Insight at Structure and Functional Activity after Four Decades of Investigation. Toxins (Basel) 2022; 15:toxins15010008. [PMID: 36668828 PMCID: PMC9863223 DOI: 10.3390/toxins15010008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/13/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022] Open
Abstract
Many human cardiovascular and neurological disorders (such as ischemia, epileptic seizures, traumatic brain injury, neuropathic pain, etc.) are associated with the abnormal functional activity of voltage-gated sodium channels (VGSCs/NaVs). Many natural toxins, including the sea anemone toxins (called neurotoxins), are an indispensable and promising tool in pharmacological researches. They have widely been carried out over the past three decades, in particular, in establishing different NaV subtypes functional properties and a specific role in various pathologies. Therefore, a large number of publications are currently dedicated to the search and study of the structure-functional relationships of new sea anemone natural neurotoxins-potential pharmacologically active compounds that specifically interact with various subtypes of voltage gated sodium channels as drug discovery targets. This review presents and summarizes some updated data on the structure-functional relationships of known sea anemone neurotoxins belonging to four structural types. The review also emphasizes the study of type 2 neurotoxins, produced by the tropical sea anemone Heteractis crispa, five structurally homologous and one unique double-stranded peptide that, due to the absence of a functionally significant Arg14 residue, loses toxicity but retains the ability to modulate several VGSCs subtypes.
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Keely SJ, Urso A, Ilyaskin AV, Korbmacher C, Bunnett NW, Poole DP, Carbone SE. Contributions of bile acids to gastrointestinal physiology as receptor agonists and modifiers of ion channels. Am J Physiol Gastrointest Liver Physiol 2022; 322:G201-G222. [PMID: 34755536 PMCID: PMC8782647 DOI: 10.1152/ajpgi.00125.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 10/28/2021] [Accepted: 11/08/2021] [Indexed: 02/03/2023]
Abstract
Bile acids (BAs) are known to be important regulators of intestinal motility and epithelial fluid and electrolyte transport. Over the past two decades, significant advances in identifying and characterizing the receptors, transporters, and ion channels targeted by BAs have led to exciting new insights into the molecular mechanisms involved in these processes. Our appreciation of BAs, their receptors, and BA-modulated ion channels as potential targets for the development of new approaches to treat intestinal motility and transport disorders is increasing. In the current review, we aim to summarize recent advances in our knowledge of the different BA receptors and BA-modulated ion channels present in the gastrointestinal system. We discuss how they regulate motility and epithelial transport, their roles in pathogenesis, and their therapeutic potential in a range of gastrointestinal diseases.
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Affiliation(s)
- Stephen J Keely
- Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, Ireland
| | - Andreacarola Urso
- Department of Surgery, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York
- Department of Pharmacology, Columbia University, New York, New York
| | - Alexandr V Ilyaskin
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Bavaria, Germany
| | - Christoph Korbmacher
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Bavaria, Germany
| | - Nigel W Bunnett
- Department of Molecular Pathobiology, Neuroscience Institute, New York University, New York, New York
- Department of Neuroscience and Physiology, Neuroscience Institute, New York University, New York, New York
| | - Daniel P Poole
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Australian Research Council, Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Simona E Carbone
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Australian Research Council, Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
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Kim G, Nakamura M, Cho JH, Nam S, Jang IS. Sevoflurane modulation of tetrodotoxin-resistant Na+ channels in small-sized dorsal root ganglion neurons of rats. Neuroreport 2021; 32:1335-1340. [PMID: 34718245 DOI: 10.1097/wnr.0000000000001731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Volatile anesthetics are widely used for general anesthesia during surgical operations. Voltage-gated Na+ channels expressed in central neurons are major targets for volatile anesthetics; but it is unclear whether these drugs modulate native tetrodotoxin-resistant (TTX-R) Na+ channels, which are involved in the development and maintenance of inflammatory pain. METHODS In this study, we examined the effects of sevoflurane on TTX-R Na+ currents (INa) in acutely isolated rat dorsal root ganglion neurons, using a whole-cell patch-clamp technique. RESULTS Sevoflurane slightly potentiated the peak amplitude of transient TTX-R INa but more potently inhibited slow voltage-ramp-induced persistent INa in a concentration-dependent manner. Sevoflurane (0.86 ± 0.02 mM) (1) slightly shifted the steady-state fast inactivation relationship to hyperpolarizing ranges without affecting the voltage-activation relationship, (2) reduced the extent of use-dependent inhibition of Na+ channels, (3) accelerated the onset of inactivation and (4) delayed the recovery from inactivation of TTX-R Na+ channels. Thus, sevoflurane has diverse effects on TTX-R Na+ channels expressed in nociceptive neurons. CONCLUSIONS The present results suggest that the inhibition of persistent INa and the modulation of the voltage dependence and inactivation might be, at least in part, responsible for the analgesic effects elicited by sevoflurane.
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Affiliation(s)
| | - Michiko Nakamura
- Department of Pharmacology, School of Dentistry
- Brain Science & Engineering Institute, Kyungpook National University, Daegu, Republic of Korea
| | | | | | - Il-Sung Jang
- Department of Pharmacology, School of Dentistry
- Brain Science & Engineering Institute, Kyungpook National University, Daegu, Republic of Korea
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Nakamura M, Jang IS. Propranolol modulation of tetrodotoxin-resistant Na + channels in dural afferent neurons. Eur J Pharmacol 2021; 910:174449. [PMID: 34454925 DOI: 10.1016/j.ejphar.2021.174449] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 08/25/2021] [Accepted: 08/25/2021] [Indexed: 10/20/2022]
Abstract
Propranolol, a representative adrenergic β-receptor antagonist, is widely used to prevent migraine attacks. Although propranolol is well known to inhibit tetrodotoxin-resistant (TTX-R) Na+ channels in cardiac myocytes, it is unclear whether the drug modulates these channels expressed in dural afferent neurons. In this study, we examined the effects of propranolol on TTX-R Na+ channels in medium-sized dural afferent neurons identified by the fluorescent dye DiI. The TTX-R Na+ currents (INa) were recorded from acutely isolated DiI-positive neurons using a whole-cell patch clamp technique under voltage-clamp conditions. Propranolol inhibited the noninactivating steady-state component more potently than the peak component of transient TTX-R INa. Propranolol also potently inhibited the slow voltage ramp-induced TTX-R INa in a concentration-dependent manner, suggesting that it preferentially inhibited the noninactivating or persistent INa in DiI-positive neurons. Propranolol had little effect on voltage dependence, but it increased the extent of the use-dependent inhibition of TTX-R Na+ channels. Propranolol also accelerated the onset of inactivation and retarded recovery from inactivation in these channels. Under current-clamp conditions, propranolol decreased the number of action potentials elicited by depolarizing current stimuli. In conclusion, the propranolol-mediated preferential inhibition of persistent INa and modulation of the inactivation kinetics of TTX-R Na+ channels might represent additional mechanisms for migraine prophylaxis.
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Affiliation(s)
- Michiko Nakamura
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu, 41940, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu, 41940, Republic of Korea
| | - Il-Sung Jang
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu, 41940, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu, 41940, Republic of Korea.
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Aryal B, Lee Y. Histamine gustatory aversion in Drosophila melanogaster. Insect Biochem Mol Biol 2021; 134:103586. [PMID: 33992752 DOI: 10.1016/j.ibmb.2021.103586] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 04/30/2021] [Accepted: 05/01/2021] [Indexed: 06/12/2023]
Abstract
Many foods and drinks contain histamine; however, the mechanisms that drive histamine taste perception have not yet been investigated. Here, we use a simple model organism, Drosophila melanogaster, to dissect the molecular sensors required to taste histamine. We first investigated histidine and histamine taste perception by performing a binary food choice assay and electrophysiology to identify essential sensilla for histamine sensing in the labellum. Histamine was found to activate S-type sensilla, which harbor bitter-sensing gustatory receptor neurons. Moreover, unbiased genetic screening for chemoreceptors revealed that a gustatory receptor, GR22e and an ionotropic receptor, IR76b are required for histamine sensing. Ectopic expression of GR22e was sufficient to induce a response in I-type sensilla, which normally do not respond to histamine. Taken together, our findings provide new insights into the mechanisms by which insects discriminate between the toxic histamine and beneficial histidine via their taste receptors.
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Affiliation(s)
- Binod Aryal
- Department of Bio & Fermentation Convergence Technology, Kookmin University, Seoul, 02707, Republic of Korea
| | - Youngseok Lee
- Department of Bio & Fermentation Convergence Technology, Kookmin University, Seoul, 02707, Republic of Korea; Interdisciplinary Program for Bio-Health Convergence, Kookmin University, Seoul, 02707, Republic of Korea.
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Philippaert K, Kalyaanamoorthy S, Fatehi M, Long W, Soni S, Byrne NJ, Barr A, Singh J, Wong J, Palechuk T, Schneider C, Darwesh AM, Maayah ZH, Seubert JM, Barakat K, Dyck JR, Light PE. Cardiac Late Sodium Channel Current Is a Molecular Target for the Sodium/Glucose Cotransporter 2 Inhibitor Empagliflozin. Circulation 2021; 143:2188-2204. [PMID: 33832341 PMCID: PMC8154177 DOI: 10.1161/circulationaha.121.053350] [Citation(s) in RCA: 89] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 02/25/2021] [Indexed: 12/11/2022]
Abstract
BACKGROUND SGLT2 (sodium/glucose cotransporter 2) inhibitors exert robust cardioprotective effects against heart failure in patients with diabetes, and there is intense interest to identify the underlying molecular mechanisms that afford this protection. Because the induction of the late component of the cardiac sodium channel current (late-INa) is involved in the etiology of heart failure, we investigated whether these drugs inhibit late-INa. METHODS Electrophysiological, in silico molecular docking, molecular, calcium imaging, and whole heart perfusion techniques were used to address this question. RESULTS The SGLT2 inhibitor empagliflozin reduced late-INa in cardiomyocytes from mice with heart failure and in cardiac Nav1.5 sodium channels containing the long QT syndrome 3 mutations R1623Q or ΔKPQ. Empagliflozin, dapagliflozin, and canagliflozin are all potent and selective inhibitors of H2O2-induced late-INa (half maximal inhibitory concentration = 0.79, 0.58, and 1.26 µM, respectively) with little effect on peak sodium current. In mouse cardiomyocytes, empagliflozin reduced the incidence of spontaneous calcium transients induced by the late-INa activator veratridine in a similar manner to tetrodotoxin, ranolazine, and lidocaine. The putative binding sites for empagliflozin within Nav1.5 were investigated by simulations of empagliflozin docking to a three-dimensional homology model of human Nav1.5 and point mutagenic approaches. Our results indicate that empagliflozin binds to Nav1.5 in the same region as local anesthetics and ranolazine. In an acute model of myocardial injury, perfusion of isolated mouse hearts with empagliflozin or tetrodotoxin prevented activation of the cardiac NLRP3 (nuclear-binding domain-like receptor 3) inflammasome and improved functional recovery after ischemia. CONCLUSIONS Our results provide evidence that late-INa may be an important molecular target in the heart for the SGLT2 inhibitors, contributing to their unexpected cardioprotective effects.
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Affiliation(s)
- Koenraad Philippaert
- Alberta Diabetes Institute (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada.xs
- Department of Pharmacology (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada
| | - Subha Kalyaanamoorthy
- Faculty of Medicine and Dentistry (S.K., A.M.D., J.M.S., K.B.), University of Alberta, Edmonton, Canada
- Faculty of Pharmacy and Pharmaceutical Sciences (S.K., A.M.D., J.M.S., K.B.), University of Alberta, Edmonton, Canada
| | - Mohammad Fatehi
- Alberta Diabetes Institute (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada.xs
- Department of Pharmacology (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada
| | - Wentong Long
- Alberta Diabetes Institute (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada.xs
- Department of Pharmacology (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada
| | - Shubham Soni
- Department of Pediatrics (S.S., N.J.B., Z.H.M., J.R.B.D.), University of Alberta, Edmonton, Canada
| | - Nikole J. Byrne
- Department of Pediatrics (S.S., N.J.B., Z.H.M., J.R.B.D.), University of Alberta, Edmonton, Canada
| | - Amy Barr
- Alberta Diabetes Institute (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada.xs
- Department of Pharmacology (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada
| | - Jyoti Singh
- Alberta Diabetes Institute (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada.xs
- Department of Pharmacology (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada
| | - Jordan Wong
- Alberta Diabetes Institute (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada.xs
- Department of Pharmacology (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada
| | - Taylor Palechuk
- Alberta Diabetes Institute (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada.xs
- Department of Pharmacology (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada
| | - Chloe Schneider
- Alberta Diabetes Institute (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada.xs
- Department of Pharmacology (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada
| | - Ahmed M. Darwesh
- Faculty of Medicine and Dentistry (S.K., A.M.D., J.M.S., K.B.), University of Alberta, Edmonton, Canada
- Faculty of Pharmacy and Pharmaceutical Sciences (S.K., A.M.D., J.M.S., K.B.), University of Alberta, Edmonton, Canada
| | - Zaid H. Maayah
- Department of Pediatrics (S.S., N.J.B., Z.H.M., J.R.B.D.), University of Alberta, Edmonton, Canada
| | - John M. Seubert
- Alberta Diabetes Institute (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada.xs
- Department of Pharmacology (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada
- Faculty of Medicine and Dentistry (S.K., A.M.D., J.M.S., K.B.), University of Alberta, Edmonton, Canada
- Faculty of Pharmacy and Pharmaceutical Sciences (S.K., A.M.D., J.M.S., K.B.), University of Alberta, Edmonton, Canada
| | - Khaled Barakat
- Faculty of Medicine and Dentistry (S.K., A.M.D., J.M.S., K.B.), University of Alberta, Edmonton, Canada
- Faculty of Pharmacy and Pharmaceutical Sciences (S.K., A.M.D., J.M.S., K.B.), University of Alberta, Edmonton, Canada
- Li Ka Shing Institute of Virology (K.B.), University of Alberta, Edmonton, Canada
| | - Jason R.B. Dyck
- Department of Pediatrics (S.S., N.J.B., Z.H.M., J.R.B.D.), University of Alberta, Edmonton, Canada
| | - Peter E. Light
- Alberta Diabetes Institute (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada.xs
- Department of Pharmacology (K.P., M.F., W.L., A.B., J.S., J.W., T.P., C.S., J.M.S., P.E.L.), University of Alberta, Edmonton, Canada
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Li J, Yuan F, Liu Y, Zhang M, Liu Y, Zhao Y, Wang B, Chen M. Exogenous melatonin enhances salt secretion from salt glands by upregulating the expression of ion transporter and vesicle transport genes in Limonium bicolor. BMC Plant Biol 2020; 20:493. [PMID: 33109099 PMCID: PMC7590734 DOI: 10.1186/s12870-020-02703-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 10/14/2020] [Indexed: 05/06/2023]
Abstract
BACKGROUND Salt, a common environmental stress factor, inhibits plant growth and reduces yields. Melatonin is a pleiotropic molecule that regulates plant growth and can alleviate environmental stress in plants. All previous research on this topic has focused on the use of melatonin to improve the relatively low salt tolerance of glycophytes by promoting growth and enhancing antioxidant ability. It is unclear whether exogenous melatonin can increase the salt tolerance of halophytes, particularly recretohalophytes, by enhancing salt secretion from the salt glands. RESULTS To examine the mechanisms of melatonin-mediated salt tolerance, we explored the effects of exogenous applications of melatonin on the secretion of salt from the salt glands of Limonium bicolor (a kind of recretohalophyte) seedlings and on the expression of associated genes. A pretreatment with 5 μM melatonin significantly improved the growth of L. bicolor seedlings under 300 mM NaCl. Furthermore, exogenous melatonin significantly increased the dry weight and endogenous melatonin content of L. bicolor. In addition, this treatment reduced the content of Na+ and Cl- in leaves, but increased the K+ content. Both the salt secretion rate of the salt glands and the expression level of genes encoding ion transporters (LbHTK1, LbSOS1, LbPMA, and LbNHX1) and vesicular transport proteins (LbVAMP721, LbVAP27, and LbVAMP12) were significantly increased by exogenous melatonin treatment. These results indicate that melatonin improves the salt tolerance of the recretohalophyte L. bicolor via the upregulation of salt secretion by the salt glands. CONCLUSIONS Our results showed that melatonin can upregulate the expression of genes encoding ion transporters and vesicle transport proteins to enhance salt secretion from the salt glands. Combining the results of the current study with previous research, we formulated a novel mechanism by which melatonin increases salt secretion in L. bicolor. Ions in mesophyll cells are transported to the salt glands through ion transporters located at the plasma membrane. After the ions enter the salt glands, they are transported to the collecting chamber adjacent to the secretory pore through vesicle transport and ions transporter and then are secreted from the secretory pore of salt glands, which maintain ionic homeostasis in the cells and alleviate NaCl-induced growth inhibition.
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Affiliation(s)
- Junpeng Li
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Science, Shandong Normal University, 88 Wenhua East Road, Jinan, 250014, P.R. China
| | - Fang Yuan
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Science, Shandong Normal University, 88 Wenhua East Road, Jinan, 250014, P.R. China
| | - Yanlu Liu
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Science, Shandong Normal University, 88 Wenhua East Road, Jinan, 250014, P.R. China
| | - Mingjing Zhang
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Science, Shandong Normal University, 88 Wenhua East Road, Jinan, 250014, P.R. China
| | - Yun Liu
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Science, Shandong Normal University, 88 Wenhua East Road, Jinan, 250014, P.R. China
| | - Yang Zhao
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Science, Shandong Normal University, 88 Wenhua East Road, Jinan, 250014, P.R. China
| | - Baoshan Wang
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Science, Shandong Normal University, 88 Wenhua East Road, Jinan, 250014, P.R. China.
| | - Min Chen
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Science, Shandong Normal University, 88 Wenhua East Road, Jinan, 250014, P.R. China.
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Sergeevichev D, Fomenko V, Strelnikov A, Dokuchaeva A, Vasilieva M, Chepeleva E, Rusakova Y, Artemenko S, Romanov A, Salakhutdinov N, Chernyavskiy A. Botulinum Toxin-Chitosan Nanoparticles Prevent Arrhythmia in Experimental Rat Models. Mar Drugs 2020; 18:md18080410. [PMID: 32748868 PMCID: PMC7460516 DOI: 10.3390/md18080410] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/22/2020] [Accepted: 07/27/2020] [Indexed: 11/16/2022] Open
Abstract
Several experimental studies have recently demonstrated that temporary autonomic block using botulinum toxin (BoNT/A1) might be a novel option for the treatment of atrial fibrillation. However, the assessment of antiarrhythmic properties of BoNT has so far been limited, relying exclusively on vagal stimulation and rapid atrial pacing models. The present study examined the antiarrhythmic effect of specially formulated BoNT/A1-chitosan nanoparticles (BTN) in calcium chloride-, barium chloride- and electrically induced arrhythmia rat models. BTN enhanced the effect of BoNT/A1. Subepicardial injection of BTN resulted in a significant antiarrhythmic effect in investigated rat models. BTN formulation antagonizes arrhythmia induced by the activation of Ca, K and Na channels.
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Pinto DP, Coutinho DDS, Carvalho KIMD, Ferrero MR, Silva LVD, Silveira GPE, Silva DMD, Araújo JFG, Silva ACA, Pereira HM, Fonseca LBD, Faria RX, Souza MVND, Silva ETD, Santos-Filho OA, Costa JCSD, Amendoeira FC, Martins MA. Pharmacological profiling of JME-173, a novel mexiletine derivative combining dual anti-inflammatory/anti-spasmodic functions and limited action in Na + channels. Eur J Pharmacol 2020; 885:173367. [PMID: 32750364 DOI: 10.1016/j.ejphar.2020.173367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/30/2020] [Accepted: 07/09/2020] [Indexed: 12/14/2022]
Abstract
Existing evidence suggests that the local anaesthetic mexiletine can be beneficial for patients with asthma. However, caution is required since anaesthesia of the airways inhibits protective bronchodilator neuronal reflexes, limiting applications in conditions of hyperirritable airways. Here, we describe the synthesis of a new series of mexiletine analogues, which were screened for reduced activity in Na+ channels and improved smooth muscle relaxant effects, that were evaluated using the patch-clamp technique and an isolated tracheal organ bath, respectively. JME-173 (1-(4-bromo-3,5-dimethylphenoxy)propan-2-amine) was the most effective among the four mexiletine analogues investigated. JME-173 was then studied in vivo using a murine model of lung inflammation induced by cigarette smoke (CS) and in vitro using neutrophil chemotaxis and mast cell degranulation assays. Finally, the JME-173 pharmacokinetic profile was assessed using HPLC-MS/MS bioanalytical method. JME-173 directly inhibited IL-8 (CXCL8)- and FMLP-induced human neutrophil chemotaxis and allergen-induced mast cell degranulation. After oral administration 1 h before CS exposure, JME-173 (50 mg/kg) strongly reduced the increased number of macrophages and neutrophils recovered in the bronchoalveolar effluent without altering lymphocyte counts. Pharmacokinetic experiments of JME-173 (10 mg/kg, orally) showed values of maximum concentration (Cmax), maximum time (Tmax), area under the blood concentration-time curve (AUC0-t) and area under the blood concentration-time curve from 0-Inf (AUC0-inf) of 163.3 ± 38.3 ng/mL, 1.2 ± 0.3 h, 729.4 ± 118.3 ng*h/ml and 868.9 ± 117.1 ng*h/ml (means ± S.E.M.), respectively. Collectively, these findings suggest that JME-173 has the potential to be an effective oral treatment for diseases associated with bronchoconstriction and inflammation.
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Affiliation(s)
- Douglas Pereira Pinto
- Laboratory of Pharmacokinetics, Vice Presidency of Research and Innovation in Health - Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Diego de Sá Coutinho
- Laboratory of Inflammation, Instituto Oswaldo Cruz - Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | | | - Maximiliano R Ferrero
- Laboratory of Inflammation, Instituto Oswaldo Cruz - Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Letícia Vallim da Silva
- Laboratory of Pharmacokinetics, Vice Presidency of Research and Innovation in Health - Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | | | - Diego Medeiros da Silva
- Laboratory of Pharmacokinetics, Vice Presidency of Research and Innovation in Health - Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - João Felipe Garcia Araújo
- Laboratory of Pharmacokinetics, Vice Presidency of Research and Innovation in Health - Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Aline C A Silva
- Laboratory of Pharmacokinetics, Vice Presidency of Research and Innovation in Health - Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Heliana Martins Pereira
- Laboratory of Pharmacokinetics, Vice Presidency of Research and Innovation in Health - Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Laís Bastos da Fonseca
- Laboratory of Pharmacokinetics, Vice Presidency of Research and Innovation in Health - Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Robson Xavier Faria
- Laboratory of Toxoplasmosis and Other Protozoans, Oswaldo Cruz Institute, Brazil
| | - Marcus Vinicius Nora de Souza
- Laboratory of Organic Synthesis, Institute of Technology in Drugs, Farmanguinhos - Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Emerson Teixeira da Silva
- Laboratory of Organic Synthesis, Institute of Technology in Drugs, Farmanguinhos - Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Osvaldo Andrade Santos-Filho
- Laboratory of Molecular Modeling and Computational Structural Biology, Instituto de Pesquisas de Produtos Naturais - Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Fábio Coelho Amendoeira
- Department of Pharmacology and Toxicology, National Institute of Quality Control in Health - Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Marco Aurélio Martins
- Laboratory of Inflammation, Instituto Oswaldo Cruz - Fundação Oswaldo Cruz, Rio de Janeiro, Brazil.
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10
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Hwang J, Kim TY, Terentyev D, Zhong M, Kabakov AY, Bronk P, Arunachalam K, Belardinelli L, Rajamani S, Kunitomo Y, Pfeiffer Z, Lu Y, Peng X, Odening KE, Qu Z, Karma A, Koren G, Choi BR. Late I Na Blocker GS967 Supresses Polymorphic Ventricular Tachycardia in a Transgenic Rabbit Model of Long QT Type 2. Circ Arrhythm Electrophysiol 2020; 13:e006875. [PMID: 32628505 PMCID: PMC10626560 DOI: 10.1161/circep.118.006875] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND Long QT syndrome has been associated with sudden cardiac death likely caused by early afterdepolarizations (EADs) and polymorphic ventricular tachycardias (PVTs). Suppressing the late sodium current (INaL) may counterbalance the reduced repolarization reserve in long QT syndrome and prevent EADs and PVTs. METHODS We tested the effects of the selective INaL blocker GS967 on PVT induction in a transgenic rabbit model of long QT syndrome type 2 using intact heart optical mapping, cellular electrophysiology and confocal Ca2+ imaging, and computer modeling. RESULTS GS967 reduced ventricular fibrillation induction under a rapid pacing protocol (n=7/14 hearts in control versus 1/14 hearts at 100 nmol/L) without altering action potential duration or restitution and dispersion. GS967 suppressed PVT incidences by reducing Ca2+-mediated EADs and focal activity during isoproterenol perfusion (at 30 nmol/L, n=7/12 and 100 nmol/L n=8/12 hearts without EADs and PVTs). Confocal Ca2+ imaging of long QT syndrome type 2 myocytes revealed that GS967 shortened Ca2+ transient duration via accelerating Na+/Ca2+ exchanger (INCX)-mediated Ca2+ efflux from cytosol, thereby reducing EADs. Computer modeling revealed that INaL potentiates EADs in the long QT syndrome type 2 setting through (1) providing additional depolarizing currents during action potential plateau phase, (2) increasing intracellular Na+ (Nai) that decreases the depolarizing INCX thereby suppressing the action potential plateau and delaying the activation of slowly activating delayed rectifier K+ channels (IKs), suggesting important roles of INaL in regulating Nai. CONCLUSIONS Selective INaL blockade by GS967 prevents EADs and abolishes PVT in long QT syndrome type 2 rabbits by counterbalancing the reduced repolarization reserve and normalizing Nai. Graphic Abstract: A graphic abstract is available for this article.
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Affiliation(s)
- Jungmin Hwang
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
- College of Pharmacy, Univ of Rhode Island, Kingstown, RI
| | - Tae Yun Kim
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | - Dmitry Terentyev
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | | | - Anatoli Y. Kabakov
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | - Peter Bronk
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | - Karuppiah Arunachalam
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | | | - Sridharan Rajamani
- Former employee: Dept of Biology, Gilead Science, Foster City, CA
- Amgen Inc, South San Francisco, CA
| | - Yukiko Kunitomo
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | - Zachary Pfeiffer
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | - Yichun Lu
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | - Xuwen Peng
- Dept of Comparative Medicine, Pennsylvania State Univ College of Medicine, Hershey, PA
| | - Katja E. Odening
- Dept of Cardiology & Angiology I, Heart Ctr, Univ of Freiburg, Germany
| | - Zhilin Qu
- Dept of Medicine, Univ of California, Los Angeles
| | - Alain Karma
- Dept of Physics, Northeastern Univ, Boston, MA
| | - Gideon Koren
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | - Bum-Rak Choi
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
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11
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Zhou Y, Cai S, Gomez K, Wijeratne EMK, Ji Y, Bellampalli SS, Luo S, Moutal A, Gunatilaka AAL, Khanna R. 1-O-Acetylgeopyxin A, a derivative of a fungal metabolite, blocks tetrodotoxin-sensitive voltage-gated sodium, calcium channels and neuronal excitability which correlates with inhibition of neuropathic pain. Mol Brain 2020; 13:73. [PMID: 32393368 PMCID: PMC7216607 DOI: 10.1186/s13041-020-00616-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 05/04/2020] [Indexed: 01/03/2023] Open
Abstract
Chronic pain can be the result of an underlying disease or condition, medical treatment, inflammation, or injury. The number of persons experiencing this type of pain is substantial, affecting upwards of 50 million adults in the United States. Pharmacotherapy of most of the severe chronic pain patients includes drugs such as gabapentinoids, re-uptake blockers and opioids. Unfortunately, gabapentinoids are not effective in up to two-thirds of this population and although opioids can be initially effective, their long-term use is associated with multiple side effects. Therefore, there is a great need to develop novel non-opioid alternative therapies to relieve chronic pain. For this purpose, we screened a small library of natural products and their derivatives in the search for pharmacological inhibitors of voltage-gated calcium and sodium channels, which are outstanding molecular targets due to their important roles in nociceptive pathways. We discovered that the acetylated derivative of the ent-kaurane diterpenoid, geopyxin A, 1-O-acetylgeopyxin A, blocks voltage-gated calcium and tetrodotoxin-sensitive voltage-gated sodium channels but not tetrodotoxin-resistant sodium channels in dorsal root ganglion (DRG) neurons. Consistent with inhibition of voltage-gated sodium and calcium channels, 1-O-acetylgeopyxin A reduced reduce action potential firing frequency and increased firing threshold (rheobase) in DRG neurons. Finally, we identified the potential of 1-O-acetylgeopyxin A to reverse mechanical allodynia in a preclinical rat model of HIV-induced sensory neuropathy. Dual targeting of both sodium and calcium channels may permit block of nociceptor excitability and of release of pro-nociceptive transmitters. Future studies will harness the core structure of geopyxins for the generation of antinociceptive drugs.
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Affiliation(s)
- Yuan Zhou
- Department of Clinical Laboratory, the First Hospital of Jilin University, Changchun, 130021, China
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 North Campbell Drive, P.O. Box 245050, Tucson, AZ, 85724, USA
| | - Song Cai
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 North Campbell Drive, P.O. Box 245050, Tucson, AZ, 85724, USA
| | - Kimberly Gomez
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 North Campbell Drive, P.O. Box 245050, Tucson, AZ, 85724, USA
| | - E M Kithsiri Wijeratne
- Southwest Center for Natural Products Research, School of Natural Resources & the Environment, College of Agriculture & Life Sciences, The University of Arizona, Tucson, AZ, 85724, USA
| | - Yingshi Ji
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 North Campbell Drive, P.O. Box 245050, Tucson, AZ, 85724, USA
| | - Shreya S Bellampalli
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 North Campbell Drive, P.O. Box 245050, Tucson, AZ, 85724, USA
| | - Shizhen Luo
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 North Campbell Drive, P.O. Box 245050, Tucson, AZ, 85724, USA
| | - Aubin Moutal
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 North Campbell Drive, P.O. Box 245050, Tucson, AZ, 85724, USA
| | - A A Leslie Gunatilaka
- Southwest Center for Natural Products Research, School of Natural Resources & the Environment, College of Agriculture & Life Sciences, The University of Arizona, Tucson, AZ, 85724, USA
| | - Rajesh Khanna
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 North Campbell Drive, P.O. Box 245050, Tucson, AZ, 85724, USA.
- Neuroscience Graduate Interdisciplinary Program, College of Medicine, Tucson, AZ, 85724, USA.
- The Center for Innovation in Brain Sciences, The University of Arizona Health Sciences, Tucson, AZ, 85724, USA.
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12
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Hegyi B, Chen-Izu Y, Izu LT, Rajamani S, Belardinelli L, Bers DM, Bányász T. Balance Between Rapid Delayed Rectifier K + Current and Late Na + Current on Ventricular Repolarization: An Effective Antiarrhythmic Target? Circ Arrhythm Electrophysiol 2020; 13:e008130. [PMID: 32202931 PMCID: PMC7331791 DOI: 10.1161/circep.119.008130] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Rapid delayed rectifier K+ current (IKr) and late Na+ current (INaL) significantly shape the cardiac action potential (AP). Changes in their magnitudes can cause either long or short QT syndromes associated with malignant ventricular arrhythmias and sudden cardiac death. METHODS Physiological self AP-clamp was used to measure INaL and IKr during the AP in rabbit and porcine ventricular cardiomyocytes to test our hypothesis that the balance between IKr and INaL affects repolarization stability in health and disease conditions. RESULTS We found comparable amount of net charge carried by IKr and INaL during the physiological AP, suggesting that outward K+ current via IKr and inward Na+ current via INaL are in balance during physiological repolarization. Remarkably, IKr and INaL integrals in each control myocyte were highly correlated in both healthy rabbit and pig myocytes, despite high overall cell-to-cell variability. This close correlation was lost in heart failure myocytes from both species. Pretreatment with E-4031 to block IKr (mimicking long QT syndrome 2) or with sea anemone toxin II to impair Na+ channel inactivation (mimicking long QT syndrome 3) prolonged AP duration (APD); however, using GS-967 to inhibit INaL sufficiently restored APD to control in both cases. Importantly, INaL inhibition significantly reduced the beat-to-beat and short-term variabilities of APD. Moreover, INaL inhibition also restored APD and repolarization stability in heart failure. Conversely, pretreatment with GS-967 shortened APD (mimicking short QT syndrome), and E-4031 reverted APD shortening. Furthermore, the amplitude of AP alternans occurring at high pacing frequency was decreased by INaL inhibition, increased by IKr inhibition, and restored by combined INaL and IKr inhibitions. CONCLUSIONS Our data demonstrate that IKr and INaL are counterbalancing currents during the physiological ventricular AP and their integrals covary in individual myocytes. Targeting these ionic currents to normalize their balance may have significant therapeutic potential in heart diseases with repolarization abnormalities. Visual Overview: A visual overview is available for this article.
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Affiliation(s)
- Bence Hegyi
- Department of Pharmacology, University of California, Davis
| | - Ye Chen-Izu
- Department of Pharmacology, University of California, Davis
- Department of Biomedical Engineering, University of California, Davis
- Department of Internal Medicine/Cardiology, University of California, Davis
| | | | - Sridharan Rajamani
- Amgen, Inc., South San Francisco, University of Debrecen, Debrecen, Hungary
| | - Luiz Belardinelli
- InCarda Therapeutics, Inc., Newark, CA, University of Debrecen, Debrecen, Hungary
| | - Donald M. Bers
- Department of Pharmacology, University of California, Davis
| | - Tamás Bányász
- Department of Pharmacology, University of California, Davis
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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13
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Goldstein RH, Barkai O, Íñigo-Portugués A, Katz B, Lev S, Binshtok AM. Location and Plasticity of the Sodium Spike Initiation Zone in Nociceptive Terminals In Vivo. Neuron 2019; 102:801-812.e5. [PMID: 30926280 DOI: 10.1016/j.neuron.2019.03.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 01/15/2019] [Accepted: 03/01/2019] [Indexed: 11/18/2022]
Abstract
Nociceptive terminals possess the elements for detecting, transmitting, and modulating noxious signals, thus being pivotal for pain sensation. Despite this, a functional description of the transduction process by the terminals, in physiological conditions, has not been fully achieved. Here, we studied how nociceptive terminals in vivo convert noxious stimuli into propagating signals. By monitoring noxious-stimulus-induced Ca2+ dynamics from mouse corneal terminals, we found that initiation of Na+ channel (Nav)-dependent propagating signals takes place away from the terminal and that the starting point for Nav-mediated propagation depends on Nav functional availability. Acute treatment with the proinflammatory cytokines tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) resulted in a shift of the location of Nav involvement toward the terminal, thus increasing nociceptive excitability. Moreover, a shift of Nav involvement toward the terminal occurs in corneal hyperalgesia resulting from acute photokeratitis. This dynamic change in the location of Nav-mediated propagation initiation could underlie pathological pain hypersensitivity.
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Affiliation(s)
- Robert H Goldstein
- Department of Medical Neurobiology, Institute for Medical Research Israel Canada, Faculty of Medicine, The Hebrew University, 9112001 Jerusalem, Israel; The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, 9112001 Jerusalem, Israel
| | - Omer Barkai
- Department of Medical Neurobiology, Institute for Medical Research Israel Canada, Faculty of Medicine, The Hebrew University, 9112001 Jerusalem, Israel; The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, 9112001 Jerusalem, Israel
| | - Almudena Íñigo-Portugués
- Instituto de Neurociencias, Universidad Miguel Hernández-CSIC, 03550 San Juan de Alicante, Spain
| | - Ben Katz
- Department of Medical Neurobiology, Institute for Medical Research Israel Canada, Faculty of Medicine, The Hebrew University, 9112001 Jerusalem, Israel; The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, 9112001 Jerusalem, Israel
| | - Shaya Lev
- Department of Medical Neurobiology, Institute for Medical Research Israel Canada, Faculty of Medicine, The Hebrew University, 9112001 Jerusalem, Israel; The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, 9112001 Jerusalem, Israel
| | - Alexander M Binshtok
- Department of Medical Neurobiology, Institute for Medical Research Israel Canada, Faculty of Medicine, The Hebrew University, 9112001 Jerusalem, Israel; The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, 9112001 Jerusalem, Israel.
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14
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Wang Y, Yang E, Wells MM, Bondarenko V, Woll K, Carnevale V, Granata D, Klein ML, Eckenhoff RG, Dailey WP, Covarrubias M, Tang P, Xu Y. Propofol inhibits the voltage-gated sodium channel NaChBac at multiple sites. J Gen Physiol 2018; 150:1317-1331. [PMID: 30018039 PMCID: PMC6122922 DOI: 10.1085/jgp.201811993] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Revised: 05/02/2018] [Accepted: 06/15/2018] [Indexed: 12/24/2022] Open
Abstract
Voltage-gated sodium (NaV) channels are important targets of general anesthetics, including the intravenous anesthetic propofol. Electrophysiology studies on the prokaryotic NaV channel NaChBac have demonstrated that propofol promotes channel activation and accelerates activation-coupled inactivation, but the molecular mechanisms of these effects are unclear. Here, guided by computational docking and molecular dynamics simulations, we predict several propofol-binding sites in NaChBac. We then strategically place small fluorinated probes at these putative binding sites and experimentally quantify the interaction strengths with a fluorinated propofol analogue, 4-fluoropropofol. In vitro and in vivo measurements show that 4-fluoropropofol and propofol have similar effects on NaChBac function and nearly identical anesthetizing effects on tadpole mobility. Using quantitative analysis by 19F-NMR saturation transfer difference spectroscopy, we reveal strong intermolecular cross-relaxation rate constants between 4-fluoropropofol and four different regions of NaChBac, including the activation gate and selectivity filter in the pore, the voltage sensing domain, and the S4-S5 linker. Unlike volatile anesthetics, 4-fluoropropofol does not bind to the extracellular interface of the pore domain. Collectively, our results show that propofol inhibits NaChBac at multiple sites, likely with distinct modes of action. This study provides a molecular basis for understanding the net inhibitory action of propofol on NaV channels.
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Affiliation(s)
- Yali Wang
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Elaine Yang
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College and Jefferson College of Biomedical Sciences, Thomas Jefferson University, Philadelphia, PA
| | - Marta M Wells
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Vasyl Bondarenko
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Kellie Woll
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA
| | - Vincenzo Carnevale
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, PA
| | - Daniele Granata
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, PA
| | - Michael L Klein
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, PA
| | - Roderic G Eckenhoff
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA
| | - William P Dailey
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA
| | - Manuel Covarrubias
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College and Jefferson College of Biomedical Sciences, Thomas Jefferson University, Philadelphia, PA
| | - Pei Tang
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Yan Xu
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA
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15
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Abstract
Tuning element relief patches (TERPs) are silicon-based titanium salt infused adhesive patches that have been developed by Tuning Element. A number of anecdotal reports have shown that TERPs diffuse pain, including chronic, inflammatory, and neuropathic. Pain is a very complex biochemical and electrical process involving sensory part, nerve transmission, and brain perception of pain. We concentrated our research on nerve transmission, which is electrical signal along the nerve (axon). This electrical signal is created by a complex activity of opening and closing of pain related ion channels and redistribution of electrically charged ions on the nerve cell membrane. Ion channels are made of different proteins, which are involved with the complex processes of opening and closing ion channels. Here, we apply the resonant recognition model to analyze ion channel proteins related to the pain transmission in order to find out, how imprints and particles within TERPs can interfere with pain related activity of ion channels.
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16
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McElroy T, McReynolds CN, Gulledge A, Knight KR, Smith WE, Albrecht EA. Differential toxicity and venom gland gene expression in Centruroides vittatus. PLoS One 2017; 12:e0184695. [PMID: 28976980 PMCID: PMC5627916 DOI: 10.1371/journal.pone.0184695] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 08/29/2017] [Indexed: 11/19/2022] Open
Abstract
Variation in venom toxicity and composition exists in many species. In this study, venom potency and venom gland gene expression was evaluated in Centruroides vittatus, size class I-II (immature) and size class IV (adults/penultimate instars) size classes. Venom toxicity was evaluated by probit analysis and returned ED50 values of 50.1 μg/g for class IV compared to 134.2 μg/g for class I-II 24 hours post injection, suggesting size class IV was 2.7 fold more potent. Next generation sequencing (NGS and qPCR were used to characterize venom gland gene expression. NGS data was assembled into 36,795 contigs, and annotated using BLASTx with UNIPROT. EdgeR analysis of the sequences showed statistically significant differential expression in transcripts associated with sodium and potassium channel modulation. Sodium channel modulator expression generally favored size class IV; in contrast, potassium channel modulators were favored in size class I-II expression. Real-time quantitative PCR of 14 venom toxin transcripts detected relative expression ratios that paralleled NGS data and identified potential family members or splice variants for several sodium channel modulators. Our data suggests ontogenetic differences in venom potency and venom related genes expression exist between size classes I-II and IV.
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Affiliation(s)
- Thomas McElroy
- Department of Ecology, Evolution and Organismal Biology, Kennesaw State University, Kennesaw, GA, United States of America
| | - C. Neal McReynolds
- Department of Biology and Chemistry, Texas A&M International University, Laredo, TX, United States of America
| | - Alyssa Gulledge
- Department of Ecology, Evolution and Organismal Biology, Kennesaw State University, Kennesaw, GA, United States of America
| | - Kelci R. Knight
- Department of Molecular and Cellular Biology, Kennesaw State University, Kennesaw, GA, United States of America
| | - Whitney E. Smith
- Department of Molecular and Cellular Biology, Kennesaw State University, Kennesaw, GA, United States of America
| | - Eric A. Albrecht
- Department of Molecular and Cellular Biology, Kennesaw State University, Kennesaw, GA, United States of America
- * E-mail:
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17
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Enomoto A, Seki S, Tanaka S, Ishihama K, Yamanishi T, Kogo M, Hamada S. Development of resurgent and persistent sodium currents in mesencephalic trigeminal neurons. J Neurosci Res 2017; 96:305-312. [PMID: 28752895 DOI: 10.1002/jnr.24134] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 07/11/2017] [Accepted: 07/11/2017] [Indexed: 12/18/2022]
Abstract
Sodium channels play multiple roles in the formation of neural membrane properties in mesencephalic trigeminal (Mes V) neurons and in other neural systems. Mes V neurons exhibit conditional robust high-frequency spike discharges. As previously reported, resurgent and persistent sodium currents (INaR and INaP , respectively) may carry small currents at subthreshold voltages that contribute to generation of spike firing. These currents play an important role in maintaining and allowing high-frequency spike discharge during a burst. In the present study, we investigated the developmental changes in tetrodotoxin-sensitive INaR and INaP underlying high-frequency spike discharges in Mes V neurons. Whole-cell patch-clamp recordings showed that both current densities increased one and a half times from postnatal day (P) 0-6 neurons to P7-14 neurons. Although these neurons do not exhibit subthreshold oscillations or burst discharges with high-frequency firing, INaR and INaP do exist in Mes V neurons at P0-6. When the spike frequency at rheobase was examined in firing Mes V neurons, the developmental change in firing frequency among P7-14 neurons was significant. INaR and INaP density at -40 mV also increased significantly among P7-14 neurons. The change to an increase in excitability in the P7-14 group could result from this quantitative change in INaP. In neurons older than P7 that exhibit repetitive firing, quantitative increases in INaR and INaP density may be major factors that facilitate and promote high-frequency firing as a function of age in Mes V neurons.
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Affiliation(s)
- Akifumi Enomoto
- Department of Oral and Maxillofacial Surgery, Kindai University Faculty of Medicine, Osaka-Sayama, Japan
- 1st Department of Oral Maxillofacial Surgery, Graduate School of Dentistry, Osaka University, Osaka, Japan
| | - Soju Seki
- 1st Department of Oral Maxillofacial Surgery, Graduate School of Dentistry, Osaka University, Osaka, Japan
| | - Susumu Tanaka
- 1st Department of Oral Maxillofacial Surgery, Graduate School of Dentistry, Osaka University, Osaka, Japan
| | - Kohji Ishihama
- 1st Department of Oral Maxillofacial Surgery, Graduate School of Dentistry, Osaka University, Osaka, Japan
| | - Tadashi Yamanishi
- 1st Department of Oral Maxillofacial Surgery, Graduate School of Dentistry, Osaka University, Osaka, Japan
| | - Mikihiko Kogo
- 1st Department of Oral Maxillofacial Surgery, Graduate School of Dentistry, Osaka University, Osaka, Japan
| | - Suguru Hamada
- Department of Oral and Maxillofacial Surgery, Kindai University Faculty of Medicine, Osaka-Sayama, Japan
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18
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El-Battrawy I, Lang S, Zhao Z, Akin I, Yücel G, Meister S, Patocskai B, Behnes M, Rudic B, Tülümen E, Liebe V, Tiburcy M, Dworacek J, Zimmermann WH, Utikal J, Wieland T, Borggrefe M, Zhou XB. Hyperthermia Influences the Effects of Sodium Channel Blocking Drugs in Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes. PLoS One 2016; 11:e0166143. [PMID: 27829006 PMCID: PMC5102382 DOI: 10.1371/journal.pone.0166143] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Accepted: 10/24/2016] [Indexed: 12/22/2022] Open
Abstract
Introduction Fever can increase the susceptibility to supraventricular and ventricular arrhythmias, in which sodium channel dysfunction has been implicated. Whether fever influences the efficacy of sodium channel blocking drugs is unknown. The current study was designed to investigate the temperature dependent effects of distinct sodium channel blocking drugs on the sodium currents in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Methods and Results hiPSC-CMs were generated from human skin fibroblasts of a healthy donor. The peak and late sodium currents (INa), steady-state activation, inactivation and recovery from inactivation of INa in hiPSC-CMs were analyzed using the whole-cell patch clamp technique. The effects of different concentrations of the antiarrhythmic drugs flecainide, lidocaine, ajmaline and the antianginal drug ranolazine on INa were tested at 36°C and 40°C. Increasing the temperature of the bath solution from 36°C to 40°C enhanced the inhibition of peak INa but reduced the inhibition of late INa by flecainide and lidocaine. By contrast, increasing the temperature reduced the effect of ajmaline and ranolazine on the peak INa but not late INa. None of the tested drugs showed temperature-dependent effects on the steady-state activation and inactivation as well as on the recovery from inactivation of INa in hiPSC-CMs. Conclusions Temperature variation from the physiological to the febrile range apparently influences the effects of sodium channel blockers on the sodium currents. This may influence their antiarrhythmic efficacy in patients suffering from fever.
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Affiliation(s)
- Ibrahim El-Battrawy
- First Department of Medicine, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
- DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Germany
- * E-mail: (IE); (XZ)
| | - Siegfried Lang
- First Department of Medicine, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
- DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Germany
| | - Zhihan Zhao
- First Department of Medicine, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Ibrahim Akin
- First Department of Medicine, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
- DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Germany
| | - Gökhan Yücel
- First Department of Medicine, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
- DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Germany
| | - Sophie Meister
- First Department of Medicine, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Bence Patocskai
- First Department of Medicine, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
- DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Germany
| | - Michael Behnes
- First Department of Medicine, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
- DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Germany
| | - Boris Rudic
- First Department of Medicine, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
- DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Germany
| | - Erol Tülümen
- First Department of Medicine, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
- DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Germany
| | - Volker Liebe
- First Department of Medicine, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Malte Tiburcy
- DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Germany
- Institute of Pharmacology and Toxicology, University of Göttingen, Göttingen, Germany
| | - Jennifer Dworacek
- DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Germany
- Skin Cancer Unit, German Cancer Research Center (DKFZ), Heidelberg and Department of Dermatology, Venereology and Allergology, University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany
| | - Wolfram-Hubertus Zimmermann
- DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Germany
- Institute of Pharmacology and Toxicology, University of Göttingen, Göttingen, Germany
| | - Jochen Utikal
- DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Germany
- Skin Cancer Unit, German Cancer Research Center (DKFZ), Heidelberg and Department of Dermatology, Venereology and Allergology, University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany
| | - Thomas Wieland
- DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Germany
- Institute of Experimental and Clinical Pharmacology and Toxicology, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Martin Borggrefe
- First Department of Medicine, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
- DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Germany
| | - Xiao-Bo Zhou
- First Department of Medicine, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
- DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Germany
- Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan, China
- * E-mail: (IE); (XZ)
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De Mello WC, Ferrario CM, Jessup JA. Beneficial versus harmful effects of Angiotensin (1-7) on impulse propagation and cardiac arrhythmias in the failing heart. J Renin Angiotensin Aldosterone Syst 2016; 8:74-80. [PMID: 17703433 DOI: 10.3317/jraas.2007.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Introduction. The presence of Angiotensin (1-7) (Ang 1-7) and ACE 2 in the ventricle of cardiomyopathic hamsters as well as the influence of Ang (1-7) on membrane potential, impulse propagation and cardiac excitability were investigated. Methods. Histology and immunochemistry were used to demonstrate the presence of Ang (1-7) and ACE 2 in the ventricle of cardiomyopathic hamsters. Measurements of transmembrane potentials, conduction velocity and refractoriness were made using conventional intracellular microelectrodes. The influence of Ang (1-7) on sodium pump current was investigated in voltageclamped myocytes isolated from the ventricle. Results. The results indicated the presence of Ang (1-7) and ACE 2 in myocytes of cardiomyopathic hamsters. Moreover, Ang (1-7) (10-8 M) hyperpolarised the heart cell, increased the conduction velocity, and I reduced transiently the action potential duration. The cardiac refractoriness was also increased by the heptapeptide, an effect in part reduced by an inhibitor of mas receptor. These findings indicate that Ang (1-7) has important antiarrhythmic properties. However, the beneficial effects of Ang (1-7) are dose-dependent because at higher concentration (10-7 M) the heptapeptide elicited an appreciable increase of action potential duration and early-after depolarisations. Since losartan (10-7 M) did not counteract this effect of the high dose of the heptapeptide, it is possible to conclude that activation of AT1-receptors is not involved in this effect of Ang (1-7).To investigate the mechanism of the hyperpolarising action of Ang (1-7) the influence of the heptapeptide on the sodium potassium pump current was studied in myocytes isolated from the ventricle of cardiomyopathic hamsters. The peak pump current density was measured under voltage clamp using the whole cell configuration. The results indicated that Ang (1-7) (10—8 M) enhanced the electrogenic sodium pump, an effect suppressed by ouabain (10—7 M). Conclusions. Ang (1-7) has beneficial effects on the failing heart by activating the sodium pump, hyperpolarising the cell membrane and increasing the conduction velocity. These effects as well as the increment of refractoriness indicate that Ang (1-7) has antiarrhythmic properties. At higher concentrations (10—7 M), however, the heptapeptide induced early-after depolarisations which leads to the conclusion that an optimal generation of Ang (1-7) must be achieved to permit a protective role of Ang (1-7) on cardiac arrhythmias.
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Affiliation(s)
- Walmor C De Mello
- Department of Pharmacology, Medical Sciences Campus, School of Medicine, UPR, PR, USA.
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Jenson LJ, Anderson TD, Bloomquist JR. Insecticide sensitivity of native chloride and sodium channels in a mosquito cell line. Pestic Biochem Physiol 2016; 130:59-64. [PMID: 27155485 DOI: 10.1016/j.pestbp.2015.11.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 11/25/2015] [Accepted: 11/27/2015] [Indexed: 06/05/2023]
Abstract
The aim of this study was to investigate the utility of cultured Anopheles gambiae Sua1B cells for insecticide screening applications without genetic engineering or other treatments. Sua1B cells were exposed to the known insecticidal compounds lindane and DIDS, which inhibited cell growth at micromolar concentrations. In patch clamp studies, DIDS produced partial inhibition (69%) of chloride current amplitudes, and an IC50 of 5.1μM was determined for Sua1B cells. A sub-set of chloride currents showed no response to DIDS; however, inhibition (64%) of these currents was achieved using a low chloride saline solution, confirming their identity as chloride channels. In contrast, lindane increased chloride current amplitude (EC50=116nM), which was reversed when cells were bathed in calcium-free extracellular solution. Voltage-sensitive chloride channels were also inhibited by the presence of fenvalerate, a type 2 pyrethroid, but not significantly blocked by type 1 allethrin, an effect not previously shown in insects. Although no evidence of fast inward currents typical of sodium channels was observed, studies with fenvalerate in combination with veratridine, a sodium channel activator, revealed complete inhibition of cell growth that was best fit by a two-site binding model. The high potency effect was completely inhibited in the presence of tetrodotoxin, a specific sodium channel blocker, suggesting the presence of some type of sodium channel. Thus, Sua1B cells express native insect ion channels with potential utility for insecticide screening.
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Affiliation(s)
- Lacey J Jenson
- Emerging Pathogens Institute, Department of Entomology and Nematology, University of Florida, Gainesville, FL 32601, United States; Virginia Polytechnic Institute and State University, Department of Entomology, Blacksburg, VA 24061, United States
| | - Troy D Anderson
- Virginia Polytechnic Institute and State University, Department of Entomology, Blacksburg, VA 24061, United States
| | - Jeffrey R Bloomquist
- Emerging Pathogens Institute, Department of Entomology and Nematology, University of Florida, Gainesville, FL 32601, United States.
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Paiva ALB, Matavel A, Peigneur S, Cordeiro MN, Tytgat J, Diniz MRV, de Lima ME. Differential effects of the recombinant toxin PnTx4(5-5) from the spider Phoneutria nigriventer on mammalian and insect sodium channels. Biochimie 2015; 121:326-35. [PMID: 26747232 DOI: 10.1016/j.biochi.2015.12.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 12/28/2015] [Indexed: 01/30/2023]
Abstract
The toxin PnTx4(5-5) from the spider Phoneutria nigriventer is extremely toxic/lethal to insects but has no macroscopic behavioral effects observed in mice after intracerebral injection. Nevertheless, it was demonstrated that it inhibits the N-methyl-d-aspartate (NMDA) - subtype of glutamate receptors of cultured rat hippocampal neurons. PnTx4(5-5) has 63% identity to PnTx4(6-1), another insecticidal toxin from P. nigriventer, which can slow down the sodium current inactivation in insect central nervous system, but has no effect on Nav1.2 and Nav1.4 rat sodium channels. Here, we have cloned and heterologous expressed the toxin PnTx4(5-5) in Escherichia coli. The recombinant toxin rPnTx4(5-5) was tested on the sodium channel NavBg from the cockroach Blatella germanica and on mammalian sodium channels Nav1.2-1.6, all expressed in Xenopus leavis oocytes. We showed that the toxin has different affinity and mode of action on insect and mammalian sodium channels. The most remarkable effect was on NavBg, where rPnTx4(5-5) strongly slowed down channel inactivation (EC50 = 212.5 nM), and at 1 μM caused an increase on current peak amplitude of 105.2 ± 3.1%. Interestingly, the toxin also inhibited sodium current on all the mammalian channels tested, with the higher current inhibition on Nav1.3 (38.43 ± 8.04%, IC50 = 1.5 μM). Analysis of activation curves on Nav1.3 and Nav1.5 showed that the toxin shifts channel activation to more depolarized potentials, which can explain the sodium current inhibition. Furthermore, the toxin also slightly slowed down sodium inactivation on Nav1.3 and Nav1.6 channels. As far as we know, this is the first araneomorph toxin described which can shift the sodium channel activation to more depolarized potentials and also slows down channel inactivation.
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Affiliation(s)
- Ana L B Paiva
- Departamento de Pesquisa e Desenvolvimento, Fundação Ezequiel Dias, Belo Horizonte, Minas Gerais, Brazil; Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Alessandra Matavel
- Departamento de Pesquisa e Desenvolvimento, Fundação Ezequiel Dias, Belo Horizonte, Minas Gerais, Brazil
| | | | - Marta N Cordeiro
- Departamento de Pesquisa e Desenvolvimento, Fundação Ezequiel Dias, Belo Horizonte, Minas Gerais, Brazil
| | - Jan Tytgat
- Toxicology and Pharmacology, KU Leuven, Leuven, Belgium
| | - Marcelo R V Diniz
- Departamento de Pesquisa e Desenvolvimento, Fundação Ezequiel Dias, Belo Horizonte, Minas Gerais, Brazil
| | - Maria Elena de Lima
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
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Zhang Y, Peti-Peterdi J, Heiney KM, Riquier-Brison A, Carlson NG, Müller CE, Ecelbarger CM, Kishore BK. Clopidogrel attenuates lithium-induced alterations in renal water and sodium channels/transporters in mice. Purinergic Signal 2015; 11:507-18. [PMID: 26386699 PMCID: PMC4648798 DOI: 10.1007/s11302-015-9469-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [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: 04/28/2015] [Accepted: 09/09/2015] [Indexed: 10/23/2022] Open
Abstract
Lithium (Li) administration causes deranged expression and function of renal aquaporins and sodium channels/transporters resulting in nephrogenic diabetes insipidus (NDI). Extracellular nucleotides (ATP/ADP/UTP), via P2 receptors, regulate these transport functions. We tested whether clopidogrel bisulfate (CLPD), an antagonist of ADP-activated P2Y(12) receptor, would affect Li-induced alterations in renal aquaporins and sodium channels/transporters. Adult mice were treated for 14 days with CLPD and/or Li and euthanized. Urine and kidneys were collected for analysis. When administered with Li, CLPD ameliorated polyuria, attenuated the rise in urine prostaglandin E2 (PGE2), and resulted in significantly higher urinary arginine vasopressin (AVP) and aldosterone levels as compared to Li treatment alone. However, urine sodium excretion remained elevated. Semi-quantitative immunoblotting revealed that CLPD alone increased renal aquaporin 2 (AQP2), Na-K-2Cl cotransporter (NKCC2), Na-Cl cotransporter (NCC), and the subunits of the epithelial Na channel (ENaC) in medulla by 25-130 %. When combined with Li, CLPD prevented downregulation of AQP2, Na-K-ATPase, and NKCC2 but was less effective against downregulation of cortical α- or γ-ENaC (70 kDa band). Thus, CLPD primarily attenuated Li-induced downregulation of proteins involved in water conservation (AVP-sensitive), with modest effects on aldosterone-sensitive proteins potentially explaining sustained natriuresis. Confocal immunofluorescence microscopy revealed strong labeling for P2Y(12)-R in proximal tubule brush border and blood vessels in the cortex and less intense labeling in medullary thick ascending limb and the collecting ducts. Therefore, there is the potential for CLPD to be directly acting at the tubule sites to mediate these effects. In conclusion, P2Y(12)-R may represent a novel therapeutic target for Li-induced NDI.
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Affiliation(s)
- Yue Zhang
- Department of Internal Medicine and Center on Aging, University of Utah Health Sciences Center & Veterans Affairs Salt Lake City Health Care System, 500 Foothill Drive (151M), Salt Lake City, UT, 84148, USA
| | - János Peti-Peterdi
- Zilkha Neurogenetic Institute and Department of Physiology and Biophysics, University of Southern California, 1501 San Pablo Street, ZNI 313, Los Angeles, CA, 90033, USA
| | - Kristina M Heiney
- Department of Internal Medicine and Center on Aging, University of Utah Health Sciences Center & Veterans Affairs Salt Lake City Health Care System, 500 Foothill Drive (151M), Salt Lake City, UT, 84148, USA
| | - Anne Riquier-Brison
- Zilkha Neurogenetic Institute and Department of Physiology and Biophysics, University of Southern California, 1501 San Pablo Street, ZNI 313, Los Angeles, CA, 90033, USA
| | - Noel G Carlson
- Department of Neurobiology and Anatomy and Center on Aging Geriatric Research, Education, and Clinical Center (GRECC), University of Utah Health Sciences Center & Veterans Affairs Salt Lake City Health Care System, 500 Foothill Drive (151B), Salt Lake City, UT, 84148, USA
| | - Christa E Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121, Bonn, Germany
| | - Carolyn M Ecelbarger
- Department of Medicine, Center for the Study of Sex Differences in Health, Aging, and Disease, Georgetown University, 4000 Reservoir Road NW Bldg D, Rm 392, Washington, DC, 20057, USA
| | - Bellamkonda K Kishore
- Department of Internal Medicine and Center on Aging, University of Utah Health Sciences Center & Veterans Affairs Salt Lake City Health Care System, 500 Foothill Drive (151M), Salt Lake City, UT, 84148, USA.
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Abstract
ABSTRACT:Background:Controversial data was published about the sodium channel-blocking effect of the endogenous pentapeptide QYNAD, which is elevated in patients with multiple sclerosis and Guillain-Barré-syndrome. In some experiments with single cells and nerve preparations QYNAD inhibited sodium currents to the same extent as the known sodium channel blocker lidocaine whereas in other laboratory testing QYNAD failed to show any effect at all.Methods:Micro-electrode arrays with cultured neuronal networks are highly suitable to determine neuroactive activity of applied substances. The impact on electrophysiological parameter changes was compared between QYNAD and the established sodium channel blockers lidocaine and tetrodotoxin (TTX).Results:QYNAD did not alter network activity whereas the sodium channel blockers lidocaine (IC50 14.9 µM) and tetrodotoxin (IC50 1.1 nM) reversibly decreased network activity in similar concentrations as in patch-clamp experiments. This decrease of spontaneous electrophysiological activity was achieved by prolonging the interburst-interval.Conclusion:Although QYNAD might have mild effects on single-cell sodium currents, there is no significant effect on neuronal network function. These results raise concerns about QYNAD exhibiting a relevant impact on functional disability of the central nervous system in patients.
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Affiliation(s)
- F Otto
- Department of Neurology, Heinrich-Heine-University Düisseldorf, Germany
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Abstract
Painful neuropathies are frequently encountered in clinical practice as an early or late complication of several systemic disorders. Among them, diabetes is one of the most important due to its epidemiology and the relevance for regulatory agencies in the assessment of efficacy of new analgesics. However, the presentation and course of painful neuropathies, as well as the response to available drugs, are highly variable and unpredictable, posing significant challenges in the management of patients. Experimental and clinical studies have suggested that polymorphisms and mutations in pain-related genes are involved in the facilitation or inhibition of nociception, and might modulate neuropathic pain and the response to analgesics in patients. Voltage-gated sodium channel genes are among the most relevant, due to the key role of these membrane proteins in the physiology of nociception and their involvement in the pathogenesis of idiopathic painful small fiber neuropathies. These compelling features make sodium channel candidate targets for a novel approach to painful diabetic and idiopathic neuropathies, which will hopefully allow a new classification of patients and more effective targeted treatments.
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Affiliation(s)
- Giuseppe Lauria
- Neuroalgology and Headache Unit, IRCCS Foundation "Carlo Besta" Neurological Institute, Via Celoria, 11, 20133, Milan, Italy,
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Katada R, Sugimoto K, Yoshida M, Matsumoto H. Ethanol increases astrocyte aquaporin-4 expression under hyper-sodium condition. Nihon Arukoru Yakubutsu Igakkai Zasshi 2014; 49:188-194. [PMID: 25223087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Ethanol increases brain aquaporin-4 (AQP4) expression after traumatic brain injury (TBI), leading to augment mortality and morbidity after TBI. AQP4 is regulated by sodium ion channels/transporters. Ethanol affects the ion channels/transporters. From these findings, we hypothesized that ethanol may have different effects on AQP4 expression in hypo- or hyper-sodium condition. In this study, rat primary astrocytes were incubated in iso-, hypo- or hyper-sodium MEM medium with 10% calf serum. Ethanol was added to each medium simultaneously. And to check whether hypo/hyper-sodium condition could change AQP4 expression after ethanol exposure or not, astrocytes were incubated in iso-sodium with ethanol, followed by changed to hypo/hyper-sodium with the same concentration of ethanol. Astrocyte AQP4 expression was increased in hypo-sodium exposure. Hypo-sodium with ethanol did not change AQP4 expression significantly, on the other hand, hyper-sodium with ethanol decreased AQP4 expression for short time exposure, and increased it for long time exposure. Hyper-sodium changing increased astrocyte AQP4 expression under EtOH exposure. These findings suggest that AQP4 expression is regulated by sodium ion or ion channels/transporters. And ethanol affects sodium ion channels/transporters, which is involved in AQP4 expression under ethanol.
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Lazcano-Pérez F, Vivas O, Román-González SA, Rodríguez-Bustamante E, Castro H, Arenas I, García DE, Sánchez-Puig N, Arreguín-Espinosa R. A purified Palythoa venom fraction delays sodium current inactivation in sympathetic neurons. Toxicon 2014; 82:112-6. [PMID: 24593961 DOI: 10.1016/j.toxicon.2014.02.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 02/12/2014] [Accepted: 02/20/2014] [Indexed: 12/19/2022]
Abstract
Palythoa caribaeorum is a zoanthid (Phylum Cnidaria, class Anthozoa) commonly found in shallow waters of coral reefs along the Mexican Atlantic coast. Little is known on the pharmacological and biochemical properties of the venom components of this animal group. Toxin peptides from other cnidarian venoms, like sea anemones, target sodium and potassium voltage-gated channels. In this study, we tested the activity of a low molecular weight fraction from the venom of P. caribaeorum on voltage-gated sodium channels of the superior cervical ganglion (SCG) neurons of the rat. Our results showed that this fraction delays tetrodotoxin (TTX)-sensitive sodium channel inactivation indicated by a reversible 2-fold increase of the current at the decay. A peptide responsible for this activity was isolated and characterized. Its sequence showed that it does not resemble any previously reported toxin. Together, these results evidence the presence of neurotoxins in P. caribaeorum that act on sodium channels.
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Affiliation(s)
- Fernando Lazcano-Pérez
- Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, Mexico; Posgrado en Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Mexico.
| | - Oscar Vivas
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Sergio A Román-González
- Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, Mexico
| | - Eduardo Rodríguez-Bustamante
- Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, Mexico
| | - Héctor Castro
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Isabel Arenas
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - David E García
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Nuria Sánchez-Puig
- Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, Mexico
| | - Roberto Arreguín-Espinosa
- Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, Mexico.
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Kodani Y, Furukawa Y. Electrostatic charge at position 552 affects the activation and permeation of FMRFamide-gated Na+ channels. J Physiol Sci 2014; 64:141-50. [PMID: 24415456 PMCID: PMC10717150 DOI: 10.1007/s12576-013-0303-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 12/27/2013] [Indexed: 01/31/2023]
Abstract
The FMRFamide-gated Na(+) channel (FaNaC) is a unique peptide-gated sodium channel and a member of the epithelial sodium channel/degenerin family. Previous studies have shown that an aspartate residue (Asp(552)) in the second transmembrane domain is involved in activation of the FaNaC. To examine the significance of a negative charge at position 552, we used a cysteine-modification method. Macroscopic currents of a cysteine mutant (D552C) were potentiated or inhibited by use of positively or negatively charged sulfhydryl reagents ([2-(trimethylammonium)ethyl]methanethiosulfonate bromide, MTSET, and sodium (2-sulfonatoethyl)methanethiosulfonate, MTSES, respectively). Dose-response analysis showed that treatment with MTSET increased the potency of the FMRFamide in the FaNaC whereas treatment with MTSES reduced the maximum response. Negative charge at position 552 was necessary for the characteristic inward rectification of the FaNaC. These results suggest that negative electric charge at position 552 is important to the activation and permeation properties of the FaNaC.
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Affiliation(s)
- Yu Kodani
- Laboratory of Neurobiology, Faculty of Integrated Arts and Sciences, Hiroshima University, Kagamiyama 1-7-1, Higashi-Hiroshima, 739-8521 Japan
- Present Address: Department of Physiology, Fujita Health University School of Medicine, Toyoake, Aichi 470-1192 Japan
| | - Yasuo Furukawa
- Laboratory of Neurobiology, Faculty of Integrated Arts and Sciences, Hiroshima University, Kagamiyama 1-7-1, Higashi-Hiroshima, 739-8521 Japan
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Abstract
The pedigree of voltage-gated sodium channels spans the millennia from eukaryotic members that initiate the action potential firing in excitable tissues to primordial ancestors that act as enviro-protective complexes in bacterial extremophiles. Eukaryotic sodium channels (eNavs) are central to electrical signaling throughout the cardiovascular and nervous systems in animals and are established clinical targets for the therapeutic management of epilepsy, cardiac arrhythmia, and painful syndromes as they are inhibited by local anesthetic compounds. Alternatively, bacterial voltage-gated sodium channels (bNavs) likely regulate the survival response against extreme pH conditions, electrophiles, and hypo-osmotic shock and may represent a founder of the voltage-gated cation channel family. Despite apparent differences between eNav and bNav channel physiology, gating, and gene structure, the discovery that bNavs are amenable to crystallographic study opens the door for the possibility of structure-guided rational design of the next generation of therapeutics that target eNavs. Here we summarize the gating behavior of these disparate channel members and discuss mechanisms of local anesthetic inhibition in light of the growing number of bNav structures.
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Affiliation(s)
- Ben Corry
- Research School of Biology, The Australian National University, Canberra, ACT, Australia
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Oliveira EE, Du Y, Nomura Y, Dong K. A residue in the transmembrane segment 6 of domain I in insect and mammalian sodium channels regulate differential sensitivities to pyrethroid insecticides. Neurotoxicology 2013; 38:42-50. [PMID: 23764339 PMCID: PMC3773218 DOI: 10.1016/j.neuro.2013.06.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [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: 03/25/2013] [Revised: 06/03/2013] [Accepted: 06/03/2013] [Indexed: 02/05/2023]
Abstract
Voltage-gated sodium channels are critical for electrical signaling in the nervous system. Pyrethroid insecticides exert their toxic action by modifying the gating of sodium channels. A valine to methionine mutation in the transmembrane segment 6 of domain I (IS6) of sodium channels from tobacco budworms (Heliothis virescens) has been shown to alter channel gating and reduce insect sodium channel sensitivity to pyrethroids. A valine to leucine substitution was subsequently reported in pyrethroid-resistant bedbug populations. Intriguingly, pyrethroid-resistant mammalian sodium channels possess an isoleucine at the corresponding position. To determine whether different substitutions at this position alter channel gating and confer pyrethroid resistance, we made valine to methionine, isoleucine or leucine substitutions at the corresponding position, V409, in a cockroach sodium channel and examined the gating properties and pyrethroid sensitivity of the three mutants in Xenopus oocytes. All three mutations reduced the channel sensitivity to three pyrethroids (permethrin, cismethrin and deltamethrin). V409M, but not V409I or V409L, caused 6-7mV depolarizing shifts in the voltage dependences of both activation and inactivation. V409M and V409L slowed channel activation kinetics and accelerated open-state deactivation kinetics, but V409I did not. Furthermore, the substitution of isoleucine with valine, but not with methionine nor leucine, at the corresponding position in a rat skeletal muscle sodium channel, rNav1.4, enhanced channel sensitivity to deltamethrin. Collectively, our study highlights an important role of residues at 409 in regulating not only sodium channel gating, but also the differential sensitivities of insect and mammalian sodium channels to pyrethroids.
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Affiliation(s)
| | - Yuzhe Du
- Department of Entomology, Genetics and Neuroscience Programs; Michigan State University; East Lansing, MI 48824, USA
| | - Yoshiko Nomura
- Department of Entomology, Genetics and Neuroscience Programs; Michigan State University; East Lansing, MI 48824, USA
| | - Ke Dong
- Department of Entomology, Genetics and Neuroscience Programs; Michigan State University; East Lansing, MI 48824, USA
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Wang L, Nomura Y, Du Y, Dong K. Differential effects of TipE and a TipE-homologous protein on modulation of gating properties of sodium channels from Drosophila melanogaster. PLoS One 2013; 8:e67551. [PMID: 23874427 PMCID: PMC3715519 DOI: 10.1371/journal.pone.0067551] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 05/20/2013] [Indexed: 12/19/2022] Open
Abstract
β subunits of mammalian sodium channels play important roles in modulating the expression and gating of mammalian sodium channels. However, there are no orthologs of β subunits in insects. Instead, an unrelated protein, TipE in Drosophila melanogaster and its orthologs in other insects, is thought to be a sodium channel auxiliary subunit. In addition, there are four TipE-homologous genes (TEH1-4) in D. melanogaster and three to four orthologs in other insect species. TipE and TEH1-3 have been shown to enhance the peak current of various insect sodium channels expressed in Xenopus oocytes. However, limited information is available on how these proteins modulate the gating of sodium channels, particularly sodium channel variants generated by alternative splicing and RNA editing. In this study, we compared the effects of TEH1 and TipE on the function of three Drosophila sodium channel splice variants, DmNav9-1, DmNav22, and DmNav26, in Xenopus oocytes. Both TipE and TEH1 enhanced the amplitude of sodium current and accelerated current decay of all three sodium channels tested. Strikingly, TEH1 caused hyperpolarizing shifts in the voltage-dependence of activation, fast inactivation and slow inactivation of all three variants. In contrast, TipE did not alter these gating properties except for a hyperpolarizing shift in the voltage-dependence of fast inactivation of DmNav26. Further analysis of the gating kinetics of DmNav9-1 revealed that TEH1 accelerated the entry of sodium channels into the fast inactivated state and slowed the recovery from both fast- and slow-inactivated states, thereby, enhancing both fast and slow inactivation. These results highlight the differential effects of TipE and TEH1 on the gating of insect sodium channels and suggest that TEH1 may play a broader role than TipE in regulating sodium channel function and neuronal excitability in vivo.
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Affiliation(s)
- Lingxin Wang
- Department of Entomology, Genetics and Neuroscience Programs, Michigan State University, East Lansing, Michigan, United States of America
| | - Yoshiko Nomura
- Department of Entomology, Genetics and Neuroscience Programs, Michigan State University, East Lansing, Michigan, United States of America
| | - Yuzhe Du
- Department of Entomology, Genetics and Neuroscience Programs, Michigan State University, East Lansing, Michigan, United States of America
| | - Ke Dong
- Department of Entomology, Genetics and Neuroscience Programs, Michigan State University, East Lansing, Michigan, United States of America
- * E-mail:
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Raju SG, Barber AF, LeBard DN, Klein ML, Carnevale V. Exploring volatile general anesthetic binding to a closed membrane-bound bacterial voltage-gated sodium channel via computation. PLoS Comput Biol 2013; 9:e1003090. [PMID: 23785267 PMCID: PMC3681623 DOI: 10.1371/journal.pcbi.1003090] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 04/26/2013] [Indexed: 01/07/2023] Open
Abstract
Despite the clinical ubiquity of anesthesia, the molecular basis of anesthetic action is poorly understood. Amongst the many molecular targets proposed to contribute to anesthetic effects, the voltage gated sodium channels (VGSCs) should also be considered relevant, as they have been shown to be sensitive to all general anesthetics tested thus far. However, binding sites for VGSCs have not been identified. Moreover, the mechanism of inhibition is still largely unknown. The recently reported atomic structures of several members of the bacterial VGSC family offer the opportunity to shed light on the mechanism of action of anesthetics on these important ion channels. To this end, we have performed a molecular dynamics "flooding" simulation on a membrane-bound structural model of the archetypal bacterial VGSC, NaChBac in a closed pore conformation. This computation allowed us to identify binding sites and access pathways for the commonly used volatile general anesthetic, isoflurane. Three sites have been characterized with binding affinities in a physiologically relevant range. Interestingly, one of the most favorable sites is in the pore of the channel, suggesting that the binding sites of local and general anesthetics may overlap. Surprisingly, even though the activation gate of the channel is closed, and therefore the pore and the aqueous compartment at the intracellular side are disconnected, we observe binding of isoflurane in the central cavity. Several sampled association and dissociation events in the central cavity provide consistent support to the hypothesis that the "fenestrations" present in the membrane-embedded region of the channel act as the long-hypothesized hydrophobic drug access pathway.
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Affiliation(s)
- S. G. Raju
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Annika F. Barber
- Department of Neuroscience, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - David N. LeBard
- Department of Chemistry, Yeshiva University, New York, New York, United States of America
| | - Michael L. Klein
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Vincenzo Carnevale
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, Pennsylvania, United States of America
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Gao Y, Xue X, Hu D, Liu W, Yuan Y, Sun H, Li L, Timothy KW, Zhang L, Li C, Yan GX. Inhibition of Late Sodium Current by Mexiletine. Circ Arrhythm Electrophysiol 2013; 6:614-22. [PMID: 23580742 DOI: 10.1161/circep.113.000092] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Yuanfeng Gao
- Heart Center, Peking University People's Hospital, Beijing, People's Republic of China
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Ayoub A, Aumann D, Hörschelmann A, Kouchekmanesch A, Paul P, Born J, Marshall L. Differential effects on fast and slow spindle activity, and the sleep slow oscillation in humans with carbamazepine and flunarizine to antagonize voltage-dependent Na+ and Ca2+ channel activity. Sleep 2013; 36:905-11. [PMID: 23729934 PMCID: PMC3649833 DOI: 10.5665/sleep.2722] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES Sleep spindles play an important functional role in sleep-dependent memory consolidation. They are a hallmark of non-rapid eye movement (NREM) sleep and are grouped by the sleep slow oscillation. Spindles are not a unitary phenomenon but are differentiated by oscillatory frequency and topography. Yet, it is still a matter of debate whether these differences relate to different generating mechanisms. As corticothalamic networks are known to be involved in the generation of spindles and the slow oscillation, with Ca2+ and Na+ conductances playing crucial roles, we employed the actions of carbamazepine and flunarizine to reduce the efficacy of Na+ and Ca2+ channels, respectively, for probing in healthy human subjects mechanisms of corticothalamocortical excitability. DESIGN For each pharmacologic substance a within-design study was conducted on 2 experimental nights in young, healthy adults. MEASUREMENTS AND RESULTS Results indicate differential effects for slow frontocortical (approximately 10 Hz) and fast centroparietal (approximately 14 Hz) spindles. Carbamazepine enhanced slow frontal spindle activity conjointly with an increment in slow oscillation power (approximately 0.75 Hz) during deep NREM sleep. In contrast, fast centroparietal spindle activity (approximately 14 Hz) was decreased by carbamazepine. Flunarizine also decreased fast-spindle electroencephalogram power, but affected neither slow frontal spindle nor slow oscillation frequency bands. CONCLUSIONS Our findings indicate a differential pharmacologic response of the two types of sleep spindles and underscore a close linkage of the generating mechanisms underlying the sleep slow oscillation and the slow frontal sleep spindles for the signal transmission processes manipulated in the current study.
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Affiliation(s)
- Amr Ayoub
- Department of Neuroendocrinology, University of Lübeck, Lübeck, Germany
- Graduate School for Computing in Medicine and Life Sciences, University of Lübeck, Lübeck, Germany
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
| | - Dominic Aumann
- Department of Neuroendocrinology, University of Lübeck, Lübeck, Germany
| | - Anne Hörschelmann
- Department of Neuroendocrinology, University of Lübeck, Lübeck, Germany
| | | | - Pia Paul
- Department of Neuroendocrinology, University of Lübeck, Lübeck, Germany
| | - Jan Born
- Department of Neuroendocrinology, University of Lübeck, Lübeck, Germany
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
| | - Lisa Marshall
- Department of Neuroendocrinology, University of Lübeck, Lübeck, Germany
- Graduate School for Computing in Medicine and Life Sciences, University of Lübeck, Lübeck, Germany
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35
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Takazawa T, Saito S. [Molecular mechanisms of chronic pain and its therapeutic strategy]. Masui 2013; 62:275-282. [PMID: 23544328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The contribution of numerous molecules for developing and maintaining the chronic pain state in patients has been gradually shown after the decade of pain control and research. However, many patients still have chronic pain which is difficult to treat even after the appearance of new analgesics. Therefore, a number of studies are still ongoing to find promising novel analgesics. We review several molecules being examined in ongoing studies including ionotropic and G-protein coupled receptors, which are mainly distributed in primary sensory afferents and/or spinal cord dorsal horn neurons.
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Affiliation(s)
- Tomonori Takazawa
- Department of Anesthesiology, Gunma University Graduate School of Medicine, Maebashi 371-8511
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Anraku K, Nonaka K, Yamaga T, Yamamoto T, Shin MC, Wakita M, Hamamoto A, Akaike N. Removal of toxin (tetrodotoxin) from puffer ovary by traditional fermentation. Toxins (Basel) 2013; 5:193-202. [PMID: 23334671 PMCID: PMC3564078 DOI: 10.3390/toxins5010193] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 01/10/2013] [Accepted: 01/11/2013] [Indexed: 11/07/2022] Open
Abstract
The amounts of puffer toxin (tetrodotoxin, TTX) extracted from the fresh and the traditional Japanese salted and fermented “Nukazuke” and “Kasuzuke” ovaries of Takifugu stictonotus (T. stictonotus) were quantitatively analyzed in the voltage-dependent sodium current (INa) recorded from mechanically dissociated single rat hippocampal CA1 neurons. The amount of TTX contained in “Nukazuke” and “Kasuzuke” ovaries decreased to 1/50–1/90 times of that of fresh ovary during a salted and successive fermented period over a few years. The final toxin concentration after fermentation was almost close to the TTX level extracted from T. Rubripes” fresh muscle that is normally eaten. It was concluded that the fermented “Nukazuke” and “Kasuzuke” ovaries of puffer fish T. Stictonotus are safe and harmless as food.
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Affiliation(s)
- Kensaku Anraku
- Research Division for Life Science, Kumamoto Health Science University, 325 Izumi-machi, Kitaku, Kumamoto 861-5598, Japan; E-Mails: (K.A.); (K.N.); (T.Y.); (T.Y.); (M.-C.S); (M.W.); (A.H.)
| | - Kiku Nonaka
- Research Division for Life Science, Kumamoto Health Science University, 325 Izumi-machi, Kitaku, Kumamoto 861-5598, Japan; E-Mails: (K.A.); (K.N.); (T.Y.); (T.Y.); (M.-C.S); (M.W.); (A.H.)
| | - Toshitaka Yamaga
- Research Division for Life Science, Kumamoto Health Science University, 325 Izumi-machi, Kitaku, Kumamoto 861-5598, Japan; E-Mails: (K.A.); (K.N.); (T.Y.); (T.Y.); (M.-C.S); (M.W.); (A.H.)
| | - Takatoshi Yamamoto
- Research Division for Life Science, Kumamoto Health Science University, 325 Izumi-machi, Kitaku, Kumamoto 861-5598, Japan; E-Mails: (K.A.); (K.N.); (T.Y.); (T.Y.); (M.-C.S); (M.W.); (A.H.)
| | - Min-Chul Shin
- Research Division for Life Science, Kumamoto Health Science University, 325 Izumi-machi, Kitaku, Kumamoto 861-5598, Japan; E-Mails: (K.A.); (K.N.); (T.Y.); (T.Y.); (M.-C.S); (M.W.); (A.H.)
| | - Masahito Wakita
- Research Division for Life Science, Kumamoto Health Science University, 325 Izumi-machi, Kitaku, Kumamoto 861-5598, Japan; E-Mails: (K.A.); (K.N.); (T.Y.); (T.Y.); (M.-C.S); (M.W.); (A.H.)
| | - Ayaka Hamamoto
- Research Division for Life Science, Kumamoto Health Science University, 325 Izumi-machi, Kitaku, Kumamoto 861-5598, Japan; E-Mails: (K.A.); (K.N.); (T.Y.); (T.Y.); (M.-C.S); (M.W.); (A.H.)
| | - Norio Akaike
- Research Division for Life Science, Kumamoto Health Science University, 325 Izumi-machi, Kitaku, Kumamoto 861-5598, Japan; E-Mails: (K.A.); (K.N.); (T.Y.); (T.Y.); (M.-C.S); (M.W.); (A.H.)
- Research Division for Clinical Pharmacology, Medical Corporation, JuryoGroup, Kumamoto Kinoh Hospital, 6-8-1 Yamamuro, Kitaku, Kumamoto 860-8518, Japan
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +81-96-275-2111; Fax: +81-96-275-2175
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Forsyth P, Sevcik C, Martínez R, Castillo C, D'Suze G. Bactridine's effects on DUM cricket neurons under voltage clamp conditions. J Insect Physiol 2012; 58:1676-1685. [PMID: 23085555 DOI: 10.1016/j.jinsphys.2012.10.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 10/08/2012] [Accepted: 10/09/2012] [Indexed: 06/01/2023]
Abstract
We describe the effects of six bactridines (150 nM) on cricket dorsal unpaired median (DUM) neurons. The addition of bactridine 2 to DUM neurons induced a large current component with a reversal potential more negative than -30 mV, most evident at the end of the pulses. This current was completely suppressed when 1 μM amiloride was applied before adding the bactridines. Since the amiloride sensitive current is able to distort the aim of our study, i.e. the effect of bactridines on sodium channels, all experiments were done in the presence of 1 μM amiloride. Most bactridines induced voltage shifts of V(1/2) of the Boltzmann inactivation voltage dependency curves in the hyperpolarizing direction. Bactridines 1, 4 and 6 reduced Na current peak by 65, 80 and 24% of the control, respectively. The sodium conductance blockage by bactridines was voltage independent at potentials >20 mV. Bactridines effect on cricket DUM neurons does not correspond to neither α- nor β-toxins. Most bactridines shifted the inactivation curves in the hyperpolarizing direction without any effects on the activation m(∞)-like curves. Also bactridines differ from other NaScpTx in that they increased an amiloride-sensitive conductance in DUM neurons. Our result suggest that the α/β classification of sodium scorpion toxins is not all encompassing. The present work shows that bactridines target more than one site: insect voltage dependent Na channels and an amiloride-sensitive ionic pathway which is under study.
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Affiliation(s)
- P Forsyth
- Instituto de Estudios Avanzados, Unidad de Neurociencias, Caracas, Venezuela
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Statland JM, Bundy BN, Wang Y, Rayan DR, Trivedi JR, Sansone VA, Salajegheh MK, Venance SL, Ciafaloni E, Matthews E, Meola G, Herbelin L, Griggs RC, Barohn RJ, Hanna MG. Mexiletine for symptoms and signs of myotonia in nondystrophic myotonia: a randomized controlled trial. JAMA 2012; 308:1357-65. [PMID: 23032552 PMCID: PMC3564227 DOI: 10.1001/jama.2012.12607] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT Nondystrophic myotonias (NDMs) are rare diseases caused by mutations in skeletal muscle ion channels. Patients experience delayed muscle relaxation causing functionally limiting stiffness and pain. Mexiletine-induced sodium channel blockade reduced myotonia in small studies; however, as is common in rare diseases, larger studies of safety and efficacy have not previously been considered feasible. OBJECTIVE To determine the effects of mexiletine for symptoms and signs of myotonia in patients with NDMs. DESIGN, SETTING, AND PARTICIPANTS A randomized, double-blind, placebo-controlled 2-period crossover study at 7 neuromuscular referral centers in 4 countries of 59 patients with NDMs conducted between December 23, 2008, and March 30, 2011, as part of the National Institutes of Health-funded Rare Disease Clinical Research Network. INTERVENTION Oral 200-mg mexiletine or placebo capsules 3 times daily for 4 weeks, followed by the opposite intervention for 4 weeks, with 1-week washout in between. MAIN OUTCOME MEASURES Patient-reported severity score of stiffness recorded on an interactive voice response (IVR) diary (scale of 1 = minimal to 9 = worst ever experienced). Secondary end points included IVR-reported changes in pain, weakness, and tiredness; clinical myotonia assessment; quantitative measure of handgrip myotonia; and Individualized Neuromuscular Quality of Life summary quality of life score (INQOL-QOL, percentage of maximal detrimental impact). RESULTS Mexiletine significantly improved patient-reported severity score stiffness on the IVR diary. Because of a statistically significant interaction between treatment and period for this outcome, primary end point is presented by period (period 1 means were 2.53 for mexiletine and 4.21 for placebo; difference, -1.68; 95% CI, -2.66 to -0.706; P < .001; period 2 means were 1.60 for mexiletine and 5.27 for placebo; difference, -3.68; 95% CI, -3.85 to -0.139; P = .04). Mexiletine improved the INQOL-QOL score (mexiletine, 14.0 vs placebo, 16.7; difference, -2.69; 95% CI, -4.07 to -1.30; P < .001) and decreased handgrip myotonia on clinical examination (mexiletine, 0.164 seconds vs placebo, 0.494 seconds; difference, -0.330; 95% CI, -0.633 to -0.142; P < .001). The most common adverse effect was gastrointestinal (9 mexiletine and 1 placebo). Two participants experienced transient cardiac effects that did not require stopping the study (1 in each group). One serious adverse event was determined to be not study related. CONCLUSION In this preliminary study of patients with NDMs, the use of mexiletine compared with placebo resulted in improved patient-reported stiffness over 4 weeks of treatment, despite some concern about the maintenance of blinding. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00832000.
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Affiliation(s)
- Jeffrey M Statland
- Department of Neurology, University of Rochester Medical Center, Rochester, NY
| | - Brian N Bundy
- Pediatrics Epidemiology Center, University of South Florida, Tampa, FL
| | - Yunxia Wang
- Department of Neurology, University of Kansas Medical Center, Kansas City, KS
| | - Dipa Raja Rayan
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
| | - Jaya R Trivedi
- Department of Neurology, University of Texas Southwestern, Dallas, TX
| | - Valeria A Sansone
- Department of Neurology, University of Milan, IRCCS Policlinico San Donato, Milan, Italy
| | - Mohammad K Salajegheh
- Department of Neurology, Neuromuscular Division, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
| | - Shannon L. Venance
- Department of Clinical Neurological Sciences, London Health Sciences Centre, London, ON Canada
| | - Emma Ciafaloni
- Department of Neurology, University of Rochester Medical Center, Rochester, NY
| | - Emma Matthews
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
| | - Giovanni Meola
- Department of Neurology, University of Milan, IRCCS Policlinico San Donato, Milan, Italy
| | - Laura Herbelin
- Department of Neurology, University of Kansas Medical Center, Kansas City, KS
| | - Robert C Griggs
- Department of Neurology, University of Rochester Medical Center, Rochester, NY
| | - Richard J Barohn
- Department of Neurology, University of Kansas Medical Center, Kansas City, KS
| | - Michael G Hanna
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
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Smith TH, Grider JR, Dewey WL, Akbarali HI. Morphine decreases enteric neuron excitability via inhibition of sodium channels. PLoS One 2012; 7:e45251. [PMID: 23028881 PMCID: PMC3448635 DOI: 10.1371/journal.pone.0045251] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 08/14/2012] [Indexed: 12/31/2022] Open
Abstract
Gastrointestinal peristalsis is significantly dependent on the enteric nervous system. Constipation due to reduced peristalsis is a major side-effect of morphine, which limits the chronic usefulness of this excellent pain reliever in man. The ionic basis for the inhibition of enteric neuron excitability by morphine is not well characterized as previous studies have mainly utilized microelectrode recordings from whole mount myenteric plexus preparations in guinea pigs. Here we have developed a Swiss-Webster mouse myenteric neuron culture and examined their electrophysiological properties by patch-clamp techniques and determined the mechanism for morphine-induced decrease in neuronal excitability. Isolated neurons in culture were confirmed by immunostaining with pan-neuronal marker, β-III tubulin and two populations were identified by calbindin and calretinin staining. Distinct neuronal populations were further identified based on the presence and absence of an afterhyperpolarization (AHP). Cells with AHP expressed greater density of sodium currents. Morphine (3 µM) significantly reduced the amplitude of the action potential, increased the threshold for spike generation but did not alter the resting membrane potential. The decrease in excitability resulted from inhibition of sodium currents. In the presence of morphine, the steady-state voltage dependence of Na channels was shifted to the left with almost 50% of channels unavailable for activation from hyperpolarized potentials. During prolonged exposure to morphine (two hours), action potentials recovered, indicative of the development of tolerance in single enteric neurons. These results demonstrate the feasibility of isolating mouse myenteric neurons and establish sodium channel inhibition as a mechanism for morphine-induced decrease in neuronal excitability.
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Affiliation(s)
- Tricia H. Smith
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - John R. Grider
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - William L. Dewey
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Hamid I. Akbarali
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, United States of America
- * E-mail:
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Powers RK, Nardelli P, Cope TC. Frequency-dependent amplification of stretch-evoked excitatory input in spinal motoneurons. J Neurophysiol 2012; 108:753-9. [PMID: 22592308 PMCID: PMC3424093 DOI: 10.1152/jn.00313.2012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [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: 04/12/2012] [Accepted: 05/12/2012] [Indexed: 11/22/2022] Open
Abstract
Voltage-dependent calcium and sodium channels mediating persistent inward currents (PICs) amplify the effects of synaptic inputs on the membrane potential and firing rate of motoneurons. CaPIC channels are thought to be relatively slow, whereas the NaPIC channels have fast kinetics. These different characteristics influence how synaptic inputs with different frequency content are amplified; the slow kinetics of Ca channels suggest that they can only contribute to amplification of low frequency inputs (<5 Hz). To characterize frequency-dependent amplification of excitatory postsynaptic potentials (EPSPs), we measured the averaged stretch-evoked EPSPs in cat medial gastrocnemius motoneurons in decerebrate cats at different subthreshold levels of membrane potential. EPSPs were produced by muscle spindle afferents activated by stretching the homonymous and synergist muscles at frequencies of 5-50 Hz. We adjusted the stretch amplitudes at different frequencies to produce approximately the same peak-to-peak EPSP amplitude and quantified the amount of amplification by expressing the EPSP integral at different levels of depolarization as a percentage of that measured with the membrane hyperpolarized. Amplification was observed at all stretch frequencies but generally decreased with increasing stretch frequency. However, in many cells the amount of amplification was greater at 10 Hz than at 5 Hz. Fast amplification was generally reduced or absent when the lidocaine derivative QX-314 was included in the electrode solution, supporting a strong contribution from Na channels. These results suggest that NaPICs can combine with CaPICs to enhance motoneuron responses to modulations of synaptic drive over a physiologically significant range of frequencies.
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Affiliation(s)
- Randall K Powers
- Department of Physiology & Biophysics, School of Medicine, University of Washington, Seattle, Washington 98195, USA.
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Scroggs RS. The distribution of low-threshold TTX-resistant Na⁺ currents in rat trigeminal ganglion cells. Neuroscience 2012; 222:205-14. [PMID: 22800565 DOI: 10.1016/j.neuroscience.2012.07.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Revised: 06/23/2012] [Accepted: 07/06/2012] [Indexed: 11/18/2022]
Abstract
The distribution of low-threshold tetrodotoxin-resistant (TTX-r) Na(+) current and its co-expression with high-threshold TTX-r Na(+) current were studied in randomly selected acutely dissociated rat trigeminal ganglion (non-identified TG cells) and TG cells serving the temporomandibular joint (TMJ-TG cells). Conditions previously shown to enhance Na(V)1.9 channel-mediated currents (holding potential (HP) -80 mV, 130-mM fluoride internally) were employed to amplify the low-threshold Na(+) current. Under these conditions, detectable low-threshold Na(+) current was exhibited by 16 out of 21 non-identified TG cells (average, 1810 ± 358 pA), and by nine of 14 TMJ-TG cells (average, 959 ± 525 pA). The low-threshold Na(+) current began to activate around -55 mV and was inactivated by holding TG cells at -60 mV and delivering 40-ms test potentials (TPs) to 0 mV. The inactivation was long lasting, recovering only 8 ± 3% over a 5-min period after the HP was returned to -80 mV. Following low-threshold Na(+) current inactivation, high-threshold TTX-r Na(+) current, evoked from HP -60 mV, was observed. High-threshold Na(+) current amplitude averaged 16,592 ± 3913 pA for TPs to 0 mV, was first detectable at an average TP of -34 ± 1.3 mV, and was ½ activated at -7.1 ± 2.3 mV. In TG cells expressing prominent low-threshold Na(+) currents, changing the external solution to one containing 0 mM Na(+) reduced the amount of current required to hold the cells at -80 mV through -50 mV, the peak effect being observed at HP -60 mV. TG cells recorded from with a more physiological pipette solution containing chloride instead of fluoride exhibited small low-threshold Na(+) currents, which were greatly increased upon superfusion of the TG cells with the adenylyl cyclase (AC) activator forskolin. These data suggest two hypotheses: (1) low- and high-threshold Na(V)1.9 and Na(V)1.8 channels, respectively, are frequently co-expressed in TG neurons serving the TMJ and other structures, and (2), Na(V)1.9 channel-mediated currents are small under physiological conditions, but may be enhanced by inflammatory mediators that increase AC activity, and may mediate an inward leak that depolarizes TG neurons, increasing their excitability.
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Affiliation(s)
- R S Scroggs
- University of Tennessee Health Science Center, Department of Anatomy and Neurobiology, 855 Monroe Avenue, TN, USA.
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Feng S, Pflueger M, Lin SX, Groveman BR, Su J, Yu XM. Regulation of voltage-gated sodium current by endogenous Src family kinases in cochlear spiral ganglion neurons in culture. Pflugers Arch 2012; 463:571-84. [PMID: 22297656 DOI: 10.1007/s00424-012-1072-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2011] [Revised: 12/09/2011] [Accepted: 01/02/2012] [Indexed: 01/28/2023]
Abstract
Voltage-gated sodium (Na+) and potassium (K+)channels have been found to be regulated by Src family kinases(SFKs).However, how these channels are regulated by SFKs in cochlear spiral ganglion neurons (SGNs) remains unknown.Here, we report that altering the activity of endogenous SFKs modulated voltage-gated Na+, but not K+, currents recorded in embryonic SGNs in culture. Voltage-gated Na+ current was suppressed by inhibition of endogenous SFKs or just Src and potentiated by the activation of these enzymes. Detailed investigations showed that under basal conditions, SFK inhibitor application did not significantly affect the voltage-dependent activation, but shifted the steady-state inactivation curves of Na+ currents and delayed the recovery of Na+ currents from inactivation. Application of Src specific inhibitor, Src40–58,not only shifted the inactivation curve but also delayed the recovery of Na+ currents and moved the voltage-dependent activation curve towards the left. The pre-inhibition of SFKs occluded all the effects induced by Src40–58 application, except the left shift of the activation curve. The activation of SFKs did not change either steady-state inactivation or recovery of Na+ currents, but caused the left shift of the activation curve.SFK inhibitor application effectively prevented all the effects induced by SFK activation, suggesting that both the voltage-dependent activation and steady-state inactivation of Na+ current are subjects of SFK regulation. The different effects induced by activation versus inhibition of SFKs implied that under basal conditions, endogenously active and inactive SFKs might be differentially involved in the regulation of voltage-gated Na+ channels in SGNs.
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Affiliation(s)
- Shuang Feng
- Department of Otolaryngology—Head and Neck Surgery, First Affiliated Hospital, Guangxi Medical University, Nanning, Guangxi, People’s Republic of China
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Gabler M, Schubert-Zsilavecz M. [Mechanism of action of paracetamol--further contribution to discovery]. ACTA ACUST UNITED AC 2012; 41:272-4. [PMID: 22763995 DOI: 10.1002/pauz.201290068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Yang JY, Wu HJ, Wu DL. [Effects of glycyrrhetinic acid on sodium ion channel currents of rats' ventricular myocardial cells]. Zhongguo Zhong Xi Yi Jie He Za Zhi 2012; 32:944-947. [PMID: 23019953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
OBJECTIVE To study the effects of glycyrrhetinic acid (GA) on the sodium ion channel currents (I(Na)) of rats' ventricular myocardial cells, and to explore its anti-arrhythmic mechanisms at the ion channel level. METHODS Single ventricular myocardial cells was isolated from SD rats. The whole cell patch clamp was used to record the effects of GA on I(Na) of rats' ventricular myocardial cells. RESULTS GA could inhibit I(Na) of rats' ventricular myocardial cells dose-dependently. GA at 1, 5, and 10 micromol/L decreased I(Na) of rats' ventricular myocardial cells from (-4.26 +/- 0.15) nA to (-3.54 +/- 0.10) nA, (-2.19 +/- 0.09) nA, and (-1.25 +/- 0.08) nA, respectively. GA at 1, 5, and 10 micromol/L inhibited I(Na) by 16.08% +/- 2.3%, 50.82% +/- 3.56%, and 75.98% +/- 5.12%, showing statistical difference when compared with the control group (P < 0.05). GA at 10 micromol/L shifted I(Na) current-voltage curve more positively, but the activation potential and the peak potential were not changed. CONCLUSION GA inhibited the I(Na) of rats' ventricular myocardial cells dose-dependently, which was possibly associated with its antiarrhythmia effects.
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Affiliation(s)
- Ji-Yuan Yang
- Department of Cardiology, Beijing Hospital of Integrated Traditional and Western Medicine, Beijing.
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Lu Z, Wu CYC, Jiang YP, Ballou LM, Clausen C, Cohen IS, Lin RZ. Suppression of phosphoinositide 3-kinase signaling and alteration of multiple ion currents in drug-induced long QT syndrome. Sci Transl Med 2012; 4:131ra50. [PMID: 22539774 PMCID: PMC3494282 DOI: 10.1126/scitranslmed.3003623] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Many drugs, including some commonly used medications, can cause abnormal heart rhythms and sudden death, as manifest by a prolonged QT interval in the electrocardiogram. Cardiac arrhythmias caused by drug-induced long QT syndrome are thought to result mainly from reductions in the delayed rectifier potassium ion (K(+)) current I(Kr). Here, we report a mechanism for drug-induced QT prolongation that involves changes in multiple ion currents caused by a decrease in phosphoinositide 3-kinase (PI3K) signaling. Treatment of canine cardiac myocytes with inhibitors of tyrosine kinases or PI3Ks caused an increase in action potential duration that was reversed by intracellular infusion of phosphatidylinositol 3,4,5-trisphosphate. The inhibitors decreased the delayed rectifier K(+) currents I(Kr) and I(Ks), the L-type calcium ion (Ca(2+)) current I(Ca,L), and the peak sodium ion (Na(+)) current I(Na) and increased the persistent Na(+) current I(NaP). Computer modeling of the canine ventricular action potential showed that the drug-induced change in any one current accounted for less than 50% of the increase in action potential duration. Mouse hearts lacking the PI3K p110α catalytic subunit exhibited a prolonged action potential and QT interval that were at least partly a result of an increase in I(NaP). These results indicate that down-regulation of PI3K signaling directly or indirectly via tyrosine kinase inhibition prolongs the QT interval by affecting multiple ion channels. This mechanism may explain why some tyrosine kinase inhibitors in clinical use are associated with increased risk of life-threatening arrhythmias.
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Affiliation(s)
- Zhongju Lu
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Chia-Yen C. Wu
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Ya-Ping Jiang
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Lisa M. Ballou
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Chris Clausen
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Ira S. Cohen
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Richard Z. Lin
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, NY 11794, USA
- Northport Veterans Affairs Medical Center, Northport, NY 11768, USA
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Laezza F. An interview with Fernanda Laezza, MD, PhD, by Vicki Glaser. Assay Drug Dev Technol 2012; 10:105-10. [PMID: 22497607 DOI: 10.1089/adt.2012.1002.pr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Blanchard MG, Rash LD, Kellenberger S. Inhibition of voltage-gated Na(+) currents in sensory neurones by the sea anemone toxin APETx2. Br J Pharmacol 2012; 165:2167-77. [PMID: 21943094 PMCID: PMC3413854 DOI: 10.1111/j.1476-5381.2011.01674.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Revised: 09/07/2011] [Accepted: 09/08/2011] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE APETx2, a toxin from the sea anemone Anthropleura elegantissima, inhibits acid-sensing ion channel 3 (ASIC3)-containing homo- and heterotrimeric channels with IC(50) values < 100 nM and 0.1-2 µM respectively. ASIC3 channels mediate acute acid-induced and inflammatory pain response and APETx2 has been used as a selective pharmacological tool in animal studies. Toxins from sea anemones also modulate voltage-gated Na(+) channel (Na(v) ) function. Here we tested the effects of APETx2 on Na(v) function in sensory neurones. EXPERIMENTAL APPROACH Effects of APETx2 on Na(v) function were studied in rat dorsal root ganglion (DRG) neurones by whole-cell patch clamp. KEY RESULTS APETx2 inhibited the tetrodotoxin (TTX)-resistant Na(v) 1.8 currents of DRG neurones (IC(50) , 2.6 µM). TTX-sensitive currents were less inhibited. The inhibition of Na(v) 1.8 currents was due to a rightward shift in the voltage dependence of activation and a reduction of the maximal macroscopic conductance. The inhibition of Na(v) 1.8 currents by APETx2 was confirmed with cloned channels expressed in Xenopus oocytes. In current-clamp experiments in DRG neurones, the number of action potentials induced by injection of a current ramp was reduced by APETx2. CONCLUSIONS AND IMPLICATIONS APETx2 inhibited Na(v) 1.8 channels, in addition to ASIC3 channels, at concentrations used in in vivo studies. The limited specificity of this toxin should be taken into account when using APETx2 as a pharmacological tool. Its dual action will be an advantage for the use of APETx2 or its derivatives as analgesic drugs.
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Affiliation(s)
- Maxime G Blanchard
- Département de Pharmacologie et Toxicologie, Université de LausanneLausanne, Switzerland
| | - Lachlan D Rash
- Institute for Molecular Bioscience, The University of QueenslandSt Lucia, Queensland, Australia
| | - Stephan Kellenberger
- Département de Pharmacologie et Toxicologie, Université de LausanneLausanne, Switzerland
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Tietze AA, Tietze D, Ohlenschläger O, Leipold E, Ullrich F, Kühl T, Mischo A, Buntkowsky G, Görlach M, Heinemann SH, Imhof D. Structurally diverse μ-conotoxin PIIIA isomers block sodium channel NaV 1.4. Angew Chem Int Ed Engl 2012; 51:4058-61. [PMID: 22407516 DOI: 10.1002/anie.201107011] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 12/22/2011] [Indexed: 12/20/2022]
Affiliation(s)
- Alesia A Tietze
- Pharmaceutical Chemistry I, Institute of Pharmacy, University of Bonn, Brühler Strasse 7, 53119 Bonn, Germany
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Zaharenko AJ, Schiavon E, Ferreira WA, Lecchi M, de Freitas JC, Richardson M, Wanke E. Characterization of selectivity and pharmacophores of type 1 sea anemone toxins by screening seven Na(v) sodium channel isoforms. Peptides 2012; 34:158-67. [PMID: 21802465 DOI: 10.1016/j.peptides.2011.07.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 07/07/2011] [Accepted: 07/07/2011] [Indexed: 12/01/2022]
Abstract
During their evolution, animals have developed a set of cysteine-rich peptides capable of binding various extracellular sites of voltage-gated sodium channels (VGSC). Sea anemone toxins that target VGSCs delay their inactivation process, but little is known about their selectivities. Here we report the investigation of three native type 1 toxins (CGTX-II, δ-AITX-Bcg1a and δ-AITX-Bcg1b) purified from the venom of Bunodosoma cangicum. Both δ-AITX-Bcg1a and δ-AITX-Bcg1b toxins were fully sequenced. The three peptides were evaluated by patch-clamp technique among Nav1.1-1.7 isoforms expressed in mammalian cell lines, and their preferential targets are Na(v)1.5>1.6>1.1. We also evaluated the role of some supposedly critical residues in the toxins which would interact with the channels, and observed that some substitutions are not critical as expected. In addition, CGTX-II and δ-AITX-Bcg1a evoke different shifts in activation/inactivation Boltzmann curves in Nav1.1 and 1.6. Moreover, our results suggest that the interaction region between toxins and VGSCs is not restricted to the supposed site 3 (S3-S4 linker of domain IV), and this may be a consequence of distinct surface of contact of each peptide vs. targeted channel. Our data suggest that the contact surfaces of each peptide may be related to their surface charges, as CGTX-II is more positive than δ-AITX-Bcg1a and δ-AITX-Bcg1b.
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Sicouri S, Pourrier M, Gibson JK, Lynch JJ, Antzelevitch C. Comparison of electrophysiological and antiarrhythmic effects of vernakalant, ranolazine, and sotalol in canine pulmonary vein sleeve preparations. Heart Rhythm 2012; 9:422-9. [PMID: 22019863 PMCID: PMC3288874 DOI: 10.1016/j.hrthm.2011.10.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 10/17/2011] [Indexed: 12/19/2022]
Abstract
BACKGROUND Vernakalant (VER) is a relatively atrial-selective antiarrhythmic drug capable of blocking potassium and sodium currents in a frequency- and voltage-dependent manner. Ranolazine (RAN) is a sodium-channel blocker shown to exert antiarrhythmic effects in pulmonary vein (PV) sleeves. dl-Sotalol (SOT) is a β-blocker commonly used in the rhythm-control treatment of atrial fibrillation. This study evaluated the electrophysiological and antiarrhythmic effects of VER, RAN, and SOT in canine PV sleeve preparations in a blinded fashion. METHODS Transmembrane action potentials were recorded from canine superfused PV sleeve preparations exposed to VER (n = 6), RAN (n = 6), and SOT (n = 6). Delayed afterdepolarizations were induced in the presence of isoproterenol and high-calcium concentrations by periods of rapid pacing. RESULTS In PV sleeves, VER, RAN, and SOT (3-30 μM) produced small (10-15 ms) increases in action potential duration. The effective refractory period, diastolic threshold of excitation, and the shortest S(1)-S(1) cycle length permitting 1:1 activation were significantly increased by VER and RAN in a rate- and concentration-dependent manner. VER and RAN significantly reduced V(max) in a concentration- and rate-dependent manner. SOT did not significantly affect the effective refractory period, V(max), diastolic threshold of excitation, or the shortest S(1)-S(1) cycle length permitting 1:1 activation. All 3 agents (3-30 μM) suppressed delayed afterdepolarization-mediated triggered activity induced by isoproterenol and high calcium. CONCLUSIONS In canine PV sleeves, the effects of VER and RAN were similar and largely characterized by concentration- and rate-dependent depression of sodium-channel-mediated parameters, which were largely unaffected by SOT. All 3 agents demonstrated an ability to effectively suppress delayed afterdepolarization-induced triggers of atrial arrhythmia.
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