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Steer EJ, Yang Z, Al-Owais MM, Kirton HM, White E, Steele DS. Flecainide induces a sustained countercurrent dependent effect on RyR2 in permeabilized WT ventricular myocytes but not in intact cells. Front Pharmacol 2023; 14:1155601. [PMID: 37124209 PMCID: PMC10130871 DOI: 10.3389/fphar.2023.1155601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 03/29/2023] [Indexed: 05/02/2023] Open
Abstract
Background and purpose: While flecainide is now an accepted treatment for arrhythmias associated with catecholaminergic polymorphic ventricular tachycardia (CPVT), its mechanism of action remains controversial. In studies on myocytes from CPVT mice, inhibition of proarrhythmic Ca2+ waves was initially attributed to a novel action on the type-2 ryanodine receptor (RyR2). However, subsequent work on wild type (WT) myocytes questioned the conclusion that flecainide has a direct action on RyR2. In the present study, the effects of flecainide were compared in intact and permeabilized WT myocytes. Experimental approach: Intracellular Ca2+ was measured using confocal microscopy in intact or saponin permeabilized adult rat ventricular myocytes (ARVM). In some experiments on permeabilized cells, flecainide was studied following partial inhibition of the sarcoplasmic reticulum (SR) counter-current. Key results: Flecainide induced sustained changes Ca2+ sparks and waves in permeabilized ARVM, which were comparable to those reported in intact or permeabilized myocytes from CPVT mice. However, a relatively high level of flecainide (25 μM) was required to induce these effects. Inhibition of the SR counter-current potentiated the effects of flecainide on SR Ca2+ waves. In intact field stimulated ARVM, prolonged exposure to 15 μM flecainide decreased wave frequency but RyR2 dependent effects on Ca2+ sparks were absent; higher drug concentrations blocked field stimulation, consistent with inhibition of Nav1.5. Conclusions and implications: In intact ARVM, the absence of effects on Ca2+ sparks suggests that the intracellular flecainide concentration was insufficient to influence RyR2. Wave inhibition in intact ARVM may reflect secondary effects of Nav1.5 inhibition. Potentiation of flecainide's action by counter-current inhibition can be explained if transient polarization of the SR membrane during SR Ca2+ release facilitates its action on RyR2.
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Pacheco-Rojas DO, Delgado-Ramírez M, Villatoro-Gómez K, Moreno-Galindo EG, Rodríguez-Menchaca AA, Sánchez-Chapula JA, Ferrer T. Riluzole inhibits Kv4.2 channels acting on the closed and closed inactivated states. Eur J Pharmacol 2021; 899:174026. [PMID: 33722592 DOI: 10.1016/j.ejphar.2021.174026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 03/02/2021] [Accepted: 03/09/2021] [Indexed: 11/18/2022]
Abstract
Riluzole is an anticonvulsant drug also used to treat the amyotrophic lateral sclerosis and major depressive disorder. This compound has antiglutamatergic activity and is an important multichannel blocker. However, little is known about its actions on the Kv4.2 channels, the molecular correlate of the A-type K+ current (IA) and the fast transient outward current (Itof). Here, we investigated the effects of riluzole on Kv4.2 channels transiently expressed in HEK-293 cells. Riluzole inhibited Kv4.2 channels with an IC50 of 190 ± 14 μM and the effect was voltage- and frequency-independent. The activation rate of the current (at +50 mV) was not affected by the drug, nor the voltage dependence of channel activation, but the inactivation rate was accelerated by 100 and 300 μM riluzole. When Kv4.2 channels were maintained at the closed state, riluzole incubation induced a tonic current inhibition. In addition, riluzole significantly shifted the voltage dependence of inactivation to hyperpolarized potentials without affecting the recovery from inactivation. In the presence of the drug, the closed-state inactivation was significantly accelerated, and the percentage of inactivated channels was increased. Altogether, our findings indicate that riluzole inhibits Kv4.2 channels mainly affecting the closed and closed-inactivated states.
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Affiliation(s)
- David O Pacheco-Rojas
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965 Col, Villas San Sebastián, Colima, COL, 28045, Mexico
| | - Mayra Delgado-Ramírez
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965 Col, Villas San Sebastián, Colima, COL, 28045, Mexico
| | - Kathya Villatoro-Gómez
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965 Col, Villas San Sebastián, Colima, COL, 28045, Mexico
| | - Eloy G Moreno-Galindo
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965 Col, Villas San Sebastián, Colima, COL, 28045, Mexico
| | - Aldo A Rodríguez-Menchaca
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, Av. Venustiano Carranza #2405, Col. Los Filtros, San Luis Potosí, SLP, 78210, Mexico
| | - José A Sánchez-Chapula
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965 Col, Villas San Sebastián, Colima, COL, 28045, Mexico.
| | - Tania Ferrer
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965 Col, Villas San Sebastián, Colima, COL, 28045, Mexico.
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Leong KM, Seligman H, Varnava AM. Proarrhythmogenic effects of lamotrigine during ajmaline testing for Brugada syndrome. HeartRhythm Case Rep 2017; 3:167-171. [PMID: 28344931 PMCID: PMC5353681 DOI: 10.1016/j.hrcr.2016.11.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Kevin M.W. Leong
- Imperial College Healthcare NHS Trust, London, United Kingdom
- Address reprint requests and correspondence: Dr Kevin Ming Wei Leong, Fellow in Electrophysiology and Inherited Cardiac Conditions, Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, Du Cane Road, London W12 0HS, UK.Fellow in Electrophysiology and Inherited Cardiac Conditions, Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, Du Cane RoadLondonW12 0HSUK
| | - Henry Seligman
- West Hertfordshire Hospitals NHS Trust, Watford, United Kingdom
| | - Amanda M. Varnava
- Imperial College Healthcare NHS Trust, London, United Kingdom
- West Hertfordshire Hospitals NHS Trust, Watford, United Kingdom
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Delaunois A, Colomar A, Depelchin BO, Cornet M. Cardiac safety of lacosamide: the non-clinical perspective. Acta Neurol Scand 2015; 132:337-45. [PMID: 25903789 DOI: 10.1111/ane.12413] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2015] [Indexed: 11/28/2022]
Abstract
OBJECTIVES Lacosamide is indicated for the adjunctive treatment of partial-onset seizures in adult patients. Unlike other sodium channel-blocking antiepileptic drugs, lacosamide selectively enhances sodium channel slow inactivation. Potential effects of lacosamide on cardiac sodium channels and their cardiovascular consequences were comprehensively assessed. This manuscript presents the non-clinical cardiac safety profile of lacosamide. METHODS Lacosamide was tested in vitro on sodium and L-type calcium currents from isolated human atrial myocytes and on hERG-mediated potassium currents from stably transfected HEK293 cells. Cardiac action potentials were recorded in guinea pig ventricular myocytes. In vivo, hemodynamic and ECG parameters were evaluated in anesthetized dogs and monkeys receiving acute cumulative intravenous doses of lacosamide. RESULTS Following intravenous dosing with lacosamide, dose-dependent PR and QRS prolongation and ECG abnormalities (loss of P waves, atrioventricular and intraventricular blocks, junctional premature contractions) were observed in anesthetized dogs and monkeys. In vitro, lacosamide reduced human cardiac sodium currents in a concentration-, voltage- and state-dependent manner. Lacosamide reductions in Vmax in guinea pig myocytes were similar to lamotrigine and carbamazepine. Lacosamide showed no relevant inhibitory effects on hERG and L-type calcium channels and did not prolong QTc in vivo. CONCLUSIONS ECG findings in anesthetized animals correlate well with in vitro sodium channel-related effects and are also consistent with those (PR prolongation, first-degree atrioventricular block) reported in healthy volunteers and patients with epilepsy. Both in vivo and in vitro effects were detected from exposure levels 1.5- to 2-fold above those achieved with the maximum-recommended human lacosamide dose (400 mg/day).
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Affiliation(s)
- A. Delaunois
- Non-Clinical Development; UCB Biopharma SPRL.; Braine l'Alleud Belgium
| | - A. Colomar
- Non-Clinical Development; UCB Biopharma SPRL.; Braine l'Alleud Belgium
| | - B. O. Depelchin
- Non-Clinical Development; UCB Biopharma SPRL.; Braine l'Alleud Belgium
| | - M. Cornet
- Non-Clinical Development; UCB Biopharma SPRL.; Braine l'Alleud Belgium
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Partial block by riluzole of muscle sodium channels in myotubes from amyotrophic lateral sclerosis patients. Neurol Res Int 2014; 2014:946073. [PMID: 25548669 PMCID: PMC4273590 DOI: 10.1155/2014/946073] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 11/18/2014] [Indexed: 12/13/2022] Open
Abstract
Denervated muscles undergo fibrillations due to spontaneous activation of voltage-gated sodium (Na(+)) channels generating action potentials. Fibrillations also occur in patients with amyotrophic lateral sclerosis (ALS). Riluzole, the only approved drug for ALS treatment, blocks voltage-gated Na(+) channels, but its effects on muscle Na(+) channels and fibrillations are yet poorly characterized. Using patch-clamp technique, we studied riluzole effect on Na(+) channels in cultured myotubes from ALS patients. Needle electromyography was used to study fibrillation potentials (Fibs) in ALS patients during riluzole treatment and after one week of suspension. Patients were clinically characterized in all recording sessions. In myotubes, riluzole (1 μM, a therapeutic concentration) reduced Na(+) current by 20%. The rate of rise and amplitude of spikes evoked by depolarizing stimuli were also reduced. Fibs were detected in all patients tested during riluzole treatment and riluzole washout had no univocal effect. Our study indicates that, in human myotubes, riluzole partially blocks Na(+) currents and affects action potentials but does not prevent firing. In line with this in vitro finding, muscle Fibs in ALS patients appear to be largely unaffected by riluzole.
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Weiss SM, Dahlstrom JE, Saint DA. Riluzole reduces arrhythmias and myocardial damage induced by coronary occlusion in anaesthetized pigs. Clin Exp Pharmacol Physiol 2013; 40:856-63. [DOI: 10.1111/1440-1681.12175] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 08/02/2013] [Accepted: 09/11/2013] [Indexed: 11/30/2022]
Affiliation(s)
- Steven M Weiss
- Australian National University Medical School; The Canberra Hospital; Canberra ACT Australia
| | - Jane E Dahlstrom
- Australian National University Medical School; The Canberra Hospital; Canberra ACT Australia
- Department of Anatomical Pathology; ACT Pathology; The Canberra Hospital; Canberra ACT Australia
| | - David A Saint
- School of Medical Sciences; University of Adelaide; Adelaide SA Australia
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Simkó J, Nagy G, Dózsa A, Lörincz I. Sinus node dysfunction due to psychotropic agents' combination. Acta Neuropsychiatr 2012; 24:247-50. [PMID: 25286819 DOI: 10.1111/j.1601-5215.2012.00639.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Background: Although sinus node dysfunction is primarily related to degenerative fibrosis of nodal tissue in the elderly, it may occur at any age secondary to other cardiac abnormalities or extrinsic causes. Pharmacologic agents including psychotropic drug therapy may also play a role.Method: We present the case of a 53-year-old woman with bipolar affective disorder in whom antipsychotic agents were suspected of inducing sinus node dysfunction.Result: The combination of psychotropic agents including lithium, quetiapine and carbamazepine (first occasion) or escitalopram (second occasion) has been implicated as a cause for sinus node dysfunction.Conclusion: Patients with severe mental illness usually require long-term psychotropic drug therapy, often in combination. This may enhance efficacy but also involves an increased risk of adverse effects including cardiotoxicity.
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Affiliation(s)
- József Simkó
- Department of Cardiology, Institute of Medicine, Semmelweis Health Care Center, Miskolc, Hungary
| | - Gabriella Nagy
- Department of Cardiology, Institute of Medicine, Semmelweis Health Care Center, Miskolc, Hungary
| | - Anikó Dózsa
- Department of Dermatology, Semmelweis Health Care Center, Miskolc, Hungary
| | - István Lörincz
- Division of Emergency Medicine, First Department of Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
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18β-Glycyrrhetinic acid preferentially blocks late Na current generated by ΔKPQ Nav1.5 channels. Acta Pharmacol Sin 2012; 33:752-60. [PMID: 22609834 DOI: 10.1038/aps.2012.22] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
AIM To compare the effects of two stereoisomeric forms of glycyrrhetinic acid on different components of Na(+) current, HERG and Kv1.5 channel currents. METHODS Wild-type (WT) and long QT syndrome type 3 (LQT-3) mutant ΔKPQ Nav1.5 channels, as well as HERG and Kv1.5 channels were expressed in Xenopus oocytes. In addition, isolated human atrial myocytes were used. Two-microelectrode voltage-clamp technique was used to record the voltage-activated currents. RESULTS Superfusion of 18β-glycyrrhetinic acid (18β-GA, 1-100 μmol/L) blocked both the peak current (I(Na,P)) and late current (I(Na,L)) generated by WT and ΔKPQ Nav1.5 channels in a concentration-dependent manner, while 18α-glycyrrhetinic acid (18α-GA) at the same concentrations had no effects. 18β-GA preferentially blocked I(Na,L) (IC(50)=37.2 ± 14.4 μmol/L) to I(Na,P) (IC(50)=100.4 ± 11.2 μmol/L) generated by ΔKPQ Nav1.5 channels. In human atrial myocytes, 18β-GA (30 μmol/L) inhibited 47% of I(Na,P) and 87% of I(Na,L) induced by Anemonia sulcata toxin (ATX-II, 30 nmol/L). Superfusion of 18β-GA (100 μmol/L) had no effects on HERG and Kv1.5 channel currents. CONCLUSION 18β-GA preferentially blocked the late Na current without affecting HERG and Kv1.5 channels.
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Heath B, Cui Y, Worton S, Lawton B, Ward G, Ballini E, Doe C, Ellis C, Patel B, McMahon N. Translation of flecainide- and mexiletine-induced cardiac sodium channel inhibition and ventricular conduction slowing from nonclinical models to clinical. J Pharmacol Toxicol Methods 2011; 63:258-68. [DOI: 10.1016/j.vascn.2010.12.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Revised: 12/20/2010] [Accepted: 12/21/2010] [Indexed: 10/18/2022]
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Saint DA. The cardiac persistent sodium current: an appealing therapeutic target? Br J Pharmacol 2008; 153:1133-42. [PMID: 18071303 PMCID: PMC2275458 DOI: 10.1038/sj.bjp.0707492] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Revised: 08/20/2007] [Accepted: 08/28/2007] [Indexed: 12/19/2022] Open
Abstract
The sodium current in the heart is not a single current with a mono-exponential decay but rather a mixture of currents with different kinetics. It is not clear whether these arise from distinct populations of channels, or from modulation of a single population. A very slowly inactivating component, [(INa(P))] I(Na(P)) is usually about 1% of the size of the peak transient current [I(Na(T))], but is enhanced by hypoxia. It contributes to Na(+) loading and cellular damage in ischaemia and re-perfusion, and perhaps to ischaemic arrhythmias. Class I antiarrhythmic agents such as flecainide, lidocaine and mexiletine generally block I(NA(P)) more potently than block of I(Na(T)) and have been used clinically to treat LQT3 syndrome, which arises because mutations in SCN5A produce defective inactivation of the cardiac sodium channel. The same approach may be useful in some pathological situations, such as ischaemic arrhythmias or diastolic dysfunction, and newer agents are being developed with this goal. For example, ranolazine blocks I(Na(P)) about 10 times more potently than I(Na(T)) and has shown promise in the treatment of angina. Alternatively, the combination of I(Na(P)) block with K(+) channel block may provide protection from the induction of Torsades de Pointe when these agents are used to treat atrial arrhythmias (eg Vernakalant). In all of these scenarios, an understanding of the role of I(Na(P)) in cardiac pathophysiology, the mechanisms by which it may affect cardiac electrophysiology and the potential side effects of blocking I(Na(P)) in the heart and elsewhere will become increasingly important.
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Affiliation(s)
- D A Saint
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA, Australia.
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Beyreuther BK, Freitag J, Heers C, Krebsfänger N, Scharfenecker U, Stöhr T. Lacosamide: a review of preclinical properties. CNS DRUG REVIEWS 2007; 13:21-42. [PMID: 17461888 PMCID: PMC6494128 DOI: 10.1111/j.1527-3458.2007.00001.x] [Citation(s) in RCA: 264] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Lacosamide (LCM), (SPM 927, (R)-2-acetamido-N-benzyl-3-methoxypropionamide, previously referred to as harkoseride or ADD 234037) is a member of a series of functionalized amino acids that were specifically synthesized as anticonvulsive drug candidates. LCM has demonstrated antiepileptic effectiveness in different rodent seizure models and antinociceptive potential in experimental animal models that reflect distinct types and symptoms of neuropathic as well as chronic inflammatory pain. Recent results suggest that LCM has a dual mode of action underlying its anticonvulsant and analgesic activity. It was found that LCM selectively enhances slow inactivation of voltage-gated sodium channels without affecting fast inactivation. Furthermore, employing proteomic affinity-labeling techniques, collapsin-response mediator protein 2 (CRMP-2 alias DRP-2) was identified as a binding partner. Follow-up experiments confirmed a functional interaction of LCM with CRMP-2 in vitro. LCM did not inhibit or induce a wide variety of cytochrome P450 enzymes at therapeutic concentrations. In safety pharmacology and toxicology studies conducted in mice, rats, rabbits, and dogs, LCM was well tolerated. Either none or only minor side effects were observed in safety studies involving the central nervous, respiratory, gastrointestinal, and renal systems and there is no indication of abuse liability. Repeated dose toxicity studies demonstrated that after either intravenous or oral administration of LCM the adverse events were reversible and consisted mostly of exaggerated pharmacodynamic effects on the CNS. No genotoxic or carcinogenic effects were observed in vivo, and LCM showed a favorable profile in reproductive and developmental animal studies. Currently, LCM is in a late stage of clinical development as an adjunctive treatment for patients with uncontrolled partial-onset seizures, and it is being assessed as monotherapy in patients with painful diabetic neuropathy. Further trials to identify LCM's potential in pain and for other indications have been initiated.
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Affiliation(s)
- Bettina K Beyreuther
- SCHWARZ BIOSCIENCES, Department of Pharmacology/Toxicology, GmbH, Monheim, Germany.
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Ahn HS, Choi JS, Choi BH, Kim MJ, Rhie DJ, Yoon SH, Jo YH, Kim MS, Sung KW, Hahn SJ. Inhibition of the cloned delayed rectifier K+ channels, Kv1.5 and Kv3.1, by riluzole. Neuroscience 2005; 133:1007-19. [PMID: 15964489 DOI: 10.1016/j.neuroscience.2005.03.041] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2004] [Revised: 03/07/2005] [Accepted: 03/10/2005] [Indexed: 11/29/2022]
Abstract
The action of riluzole, a neuroprotective drug, on cloned delayed rectifier K+ channels (Kv1.5 and Kv3.1) was examined using the whole-cell patch-clamp technique. Riluzole reversibly inhibited Kv1.5 currents in a concentration-dependent manner with an IC50 of 39.69+/-2.37 microM. G-protein inhibitors (pertussis toxin and GDPbetaS) did not prevent this inhibition of riluzole on Kv1.5. No voltage-dependent inhibition by riluzole was found over the voltage range in which channels are fully activated. Riluzole shifted the steady-state inactivation curves of Kv1.5 in a hyperpolarizing direction in a concentration-dependent manner. It accelerated the deactivation kinetics of Kv1.5 in a concentration dependent-manner, but had no effect on the steady-state activation curve. Riluzole exhibited a use-independent inhibition of Kv1.5. The effects of riluzole on Kv3.1, the Shaw-type K+ channel were also examined. Riluzole caused a concentration-dependent inhibition of Kv3.1 currents with an IC50 of 120.98+/-9.74 microM and also shifted the steady-state inactivation curve of Kv3.1 in the hyperpolarizing direction. Thus, riluzole inhibits both Kv1.5 and Kv3.1 currents in a concentration-dependent manner and interacts directly with Kv1.5 by preferentially binding to the inactivated and to the closed states of the channel.
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Affiliation(s)
- H S Ahn
- Department of Physiology, Medical Research Center, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Socho-gu, Seoul 137-701, Korea
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Bruno-Blanch L, Gálvez J, García-Domenech R. Topological virtual screening: a way to find new anticonvulsant drugs from chemical diversity. Bioorg Med Chem Lett 2003; 13:2749-54. [PMID: 12873507 DOI: 10.1016/s0960-894x(03)00535-3] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A topological virtual screening (tvs) test is presented, which is capable of identifying new drug leaders with anticonvulsant activity. Molecular structures of both anticonvulsant-active and non active compounds, extracted from the Merck Index database, were represented using topological indexes. By means of the application of a linear discriminant analysis to both sets of structures, a topological anticonvulsant model (tam) was obtained, which defines a connectivity function. On the basis of this model, 41 new structures with anticonvulsant activity have been identified by a topological virtual screening.
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Affiliation(s)
- L Bruno-Blanch
- Biological Sciences Department, Faculty of Exact Sciences, National University of La Plata, 47 and 115 Street, B1900AVV La Plata, Argentina
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Simon L, Kariya N, Pelle-Lancien E, Mazoit JX. Bupivacaine-induced QRS prolongation is enhanced by lidocaine and by phenytoin in rabbit hearts. Anesth Analg 2002; 94:203-7, table of contents. [PMID: 11772829 DOI: 10.1097/00000539-200201000-00039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
UNLABELLED Lidocaine, phenytoin, and bupivacaine are sodium channel blockers. Lidocaine displaces bupivacaine from its receptor on the sodium channel. However, lidocaine does not seem to decrease bupivacaine toxicity. Phenytoin also has been used to treat bupivacaine cardiotoxicity. To test the hypothesis that lidocaine or phenytoin might be used for the treatment of bupivacaine overdose, we compared the effects of bupivacaine on intraventricular conduction in the isolated heart of rabbits with bupivacaine and with either phenytoin or lidocaine added to bupivacaine. Twenty-four rabbit hearts were retrogradely perfused in a nonrecirculating Langendorff apparatus. The duration of QRS was measured without any drug and 10 min after infusion of 3 microM bupivacaine. Saline (control group) or increasing concentrations of either lidocaine or phenytoin was then added by 10-min-step increments. QRS duration was measured for each concentration at the end of a 10-min step. It was also determined 10 min after discontinuation of bupivacaine and after a period of washout for all drugs. QRS duration was significantly increased by adding phenytoin or lidocaine to bupivacaine. These drugs should not be used to treat the manifestations of bupivacaine toxicity. IMPLICATIONS The effects of lidocaine and phenytoin on bupivacaine-related increases in cardiac conduction time have been studied in an isolated heart preparation. Both drugs increased the QRS widening induced by bupivacaine. We conclude that none of these drugs should be used for treating bupivacaine intoxication.
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Affiliation(s)
- Lionel Simon
- Laboratoire d'Anesthésie UPRES EA 392, Université Paris-Sud, Faculté de Médecine du Kremlin-Bicêtre, France
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Simon L, Kariya N, Pelle-Lancien E, Mazoit JX. Bupivacaine-Induced QRS Prolongation is Enhanced by Lidocaine and by Phenytoin in Rabbit Hearts. Anesth Analg 2002. [DOI: 10.1213/00000539-200201000-00039] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abstract
Treating a patient with antiepileptic drugs (AEDs) may give rise to unexpected life-threatening adverse events. Despite extensive experimental and clinical testing to ensure safety, most AEDs on the market have been associated with cases of severe cutaneous reactions, serious hematological disorders, or hepatic failure. Most of these disorders emerge as idiosyncratic immune-mediated disease or are related to toxic metabolic products of the AEDs. Early diagnosis is the only means of reducing the harmful, potentially fatal effects of these reactions. A high degree of suspicion, knowledge of risk factors, and close physician-patient contact increases the likelihood of early diagnosis and treatment. When diagnosed, severe reactions must be fully documented and reported to health authorities. The very rare occurrence of life threatening events should not, in general, limit treatment decision-making. Future epidemiological, chemical, and genetic research might provide methods for ascertaining which patients are at risk, so undue exposure can be avoided.
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Affiliation(s)
- S Arroyo
- Epilepsy Unit, Hospital Clinic de Barcelona, Villarroel 170, 08036 Barcelona, Spain
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