1
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Liu JY, Beard JM, Hussain S, Sayes CM. Advancing analytical and graphical methods for binary and ternary mixtures: The toxic interactions of divalent metal ions in human lung cells. Heliyon 2024; 10:e40481. [PMID: 39634418 PMCID: PMC11615481 DOI: 10.1016/j.heliyon.2024.e40481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 11/14/2024] [Accepted: 11/14/2024] [Indexed: 12/07/2024] Open
Abstract
Humans are exposed to various environmental chemicals, particles, and pathogens that can cause adverse health outcomes. These exposures are rarely homogenous but rather complex mixtures in which the components may interact, such as through synergism or antagonism. Toxicologists have conducted preliminary investigations into binary mixtures of two components, but little work has been done to understand mixtures of three or more components. We investigated mixtures of divalent metal ions, quantifying the toxic interactions in a human lung model. Eight metals were chosen: heavy metals cadmium, copper, lead, and tin, as well as transition metals iron, manganese, nickel, and zinc. Human alveolar epithelial cells (A549) were exposed to individual metals and sixteen binary and six ternary combinations. The dose-response was modeled using logistic regression in R to extract LC50 values. Among the individual metals, the highest and lowest toxicity were observed with copper at an LC50 of 102 μM and lead at an LC50 of 5639 μM, respectively. First and second-order interaction coefficients were obtained using machine learning-based linear regression in Python. The resulting second-degree polynomial model formed either a hyperbolic or elliptical conic section, and the positive quadrant was used to produce isobolograms and contour plots. The strongest synergism and antagonism were observed in cadmium-copper and iron-zinc, respectively. A three-way interaction term was added to produce full ternary isobologram surfaces, which, to our knowledge, are a significant first in the toxicology literature.
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Affiliation(s)
- James Y. Liu
- Department of Environmental Science, Baylor University, Waco, TX 76798-7266, USA
| | - Jonathan M. Beard
- Department of Environmental Science, Baylor University, Waco, TX 76798-7266, USA
| | - Saber Hussain
- 711th Human Performance Wing, Air Force Research Laboratory, Dayton, OH, USA
| | - Christie M. Sayes
- Department of Environmental Science, Baylor University, Waco, TX 76798-7266, USA
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2
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Yang KHS, Isaev D, Oz M. Additive Inhibition of HERG Channels Expressed in Xenopus Oocytes by Antipsychotic Drugs and Citrus Juice Flavonoid Naringenin. Pharmacology 2024; 110:122-126. [PMID: 39326403 DOI: 10.1159/000541005] [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: 04/04/2024] [Accepted: 08/14/2024] [Indexed: 09/28/2024]
Abstract
INTRODUCTION Citrus juice has been shown to cause QT prolongation in electrocardiograms of healthy volunteers, and naringenin, a major flavonoid found in citrus juice, has been identified as the potent inhibitor of human ether-a-go-go-related gene (HERG) channels as the cause of QT prolongation. Inhibition of HERG channels and prolongation of QT interval by antipsychotic drugs such as haloperidol, chlorpromazine, and clozapine have also been shown. However, naringenin's effect on HERG channel function in conjunction with antipsychotic medications has not been investigated. METHODS In the present study, we evaluated the effect of combining naringenin with antipsychotics on the function of HERG channels expressed in Xenopus oocytes. RESULTS When 30 µm naringenin was added to antipsychotic drugs (1 µm haloperidol, 10 µm chlorpromazine, or 10 µm clozapine), significantly greater HERG inhibition was demonstrated, compared to the inhibition caused by antipsychotic drugs alone. Co-application studies also showed that the magnitudes of inhibitions caused by naringenin + antipsychotics were similar to that predicted by the allotopic interaction model, suggesting that naringenin and antipsychotics bind to the HERG channel at different sites. CONCLUSION The results suggest that there is an additive interaction between antipsychotics and naringenin. Due to the potential for repolarization heterogeneity and a decrease in repolarization reserve, this additive HERG inhibition may increase the risk of arrhythmias.
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Affiliation(s)
- Keun-Hang Susan Yang
- Department of Biological Sciences, Schmid College of Science and Technology, Chapman University, One University Drive, Orange, California, USA
| | - Dmytro Isaev
- Department of Cellular Membranology, Bogomoletz Institute of Physiology, Kiev, Ukraine
| | - Murat Oz
- Department of Pharmacology and Therapeutics, College of Pharmacy, Kuwait University, Kuwait City, Kuwait
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3
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Nolte TM. Calculating toxic pressure for mixtures of endocrine disruptors. Heliyon 2024; 10:e34501. [PMID: 39149076 PMCID: PMC11325677 DOI: 10.1016/j.heliyon.2024.e34501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 07/01/2024] [Accepted: 07/10/2024] [Indexed: 08/17/2024] Open
Abstract
Incidence of autoimmune disorders, birth defects, and neurological diseases rose over the past 50 years due to increasing variety and quantity of pollutants. To date, there appear few methods capable to evaluate and predict mixture effects by endocrine disruptors (EDs). For the first time, we have developed calculus to determine mixture effects by all kinds of EDs. Our method uses the golden ratio ϕ and draws from bifurcation and chaos theory. Using also the concept of molecular mimicry, we developed the equation: e f f e c t = 100 % 1 + e 5 · ∑ K i C i - n i ϕ 3 . We successfully tested the equation using a range of cohort studies and biomarkers, and for different pollutants like heavy metals, thyroid hormone mimickants, chromate/chlorate, etc. The equation is simple enough to use with only minor prior knowledge and understanding of basic algebra. The method is universal and calculation is data 'light', requiring only pollutant concentrations [C], potencies K and an integer n for endocrinal involvement. This study offers a comprehensive framework to assess the health effects of pollutant exposure across diverse populations, envisioning far-reaching impact, and presenting practical examples and insights.
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Affiliation(s)
- Tom M Nolte
- Department of Environmental Science, Institute for Water and Wetland Research, Radboud University Nijmegen, 6500, GL Nijmegen, the Netherlands
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4
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Wang J, Zeng H, Dong G, Waddell S, McCauley J, Lagrutta A. Structure-Activity Relationship and Voltage Dependence for the Drug-Drug Interaction between Amiodarone Analogs and MNI-1 at the L-type Cav Channel. J Pharmacol Exp Ther 2024; 389:229-242. [PMID: 38453526 DOI: 10.1124/jpet.123.001858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 02/17/2024] [Accepted: 02/21/2024] [Indexed: 03/09/2024] Open
Abstract
The drug-drug interaction (DDI) between amiodarone (AMIO) and sofosbuvir (SOF), a direct-acting hepatitis-C NS5B nucleotide polymerase inhibitor, has been associated with severe bradyarrhythmia in patients. Recent cryo-EM data has revealed that this DDI occurs at the α-subunit of L-type Cav channels, with AMIO binding at the fenestration site and SOF [or MSD nucleotide inhibitor #1 (MNI-1): analog of SOF] binding at the central cavity of the conductance pathway. In this study, we investigated the DDI between 21 AMIO analogs, including dronedarone (DRON) and MNI-1 (or SOF) in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and hCav1.2 models. Our findings indicate that among the tested AMIO analogs in hiPSC-CMs at clinically relevant concentrations, only three analogs (AA-9, AA-10, and AA-17) were able to effectively substitute for AMIO in this DDI with 1 µM MNI-1. This highlights the importance of the diethyl amino group of AMIO for interacting with MNI-1. In the hCav1.2 model, desethylamiodarone (AA-12) demonstrated synergy with 90 µM MNI-1, while three other analogs with modifications to the position of the diethyl amino group or removal of iodo groups showed weaker synergy with 90 µM MNI-1. Interestingly, DRON did not exhibit any interaction with 270 µM SOF or 90 µM MNI-1, suggesting that it could safely replace AMIO in patients requiring SOF treatment, other clinically relevant differences considered. Overall, our functional data align with the cryo-EM data, highlighting that this DDI is dependent on the structure of AMIO and cardiomyocyte resting membrane potential. SIGNIFICANCE STATEMENT: Our findings point to specific residues in the AMIO molecule playing a critical role in the DDI between AMIO and MNI-1 (SOF analog), confirming cryo-EM results. Applied at clinically relevant AMIO's concentrations or projected MNI-1's concentrations at the resting potentials mimicking the sinoatrial node, this DDI significantly slowed down or completely inhibited the beating of hiPSC-CMs. Finally, these in vitro results support the safe replacement of AMIO (Cordarone) with DRON (Multaq) for patients requiring SOF treatment, other clinical caveats considered.
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Affiliation(s)
- Jixin Wang
- Safety and Exploratory Pharmacology (J.W., H.Z., A.L.) and Discovery Chemistry (G.D., S.W., J.M.), Merck Research Laboratories, Merck & Co., Inc., West Point, Pennsylvania
| | - Haoyu Zeng
- Safety and Exploratory Pharmacology (J.W., H.Z., A.L.) and Discovery Chemistry (G.D., S.W., J.M.), Merck Research Laboratories, Merck & Co., Inc., West Point, Pennsylvania
| | - Grace Dong
- Safety and Exploratory Pharmacology (J.W., H.Z., A.L.) and Discovery Chemistry (G.D., S.W., J.M.), Merck Research Laboratories, Merck & Co., Inc., West Point, Pennsylvania
| | - Sherman Waddell
- Safety and Exploratory Pharmacology (J.W., H.Z., A.L.) and Discovery Chemistry (G.D., S.W., J.M.), Merck Research Laboratories, Merck & Co., Inc., West Point, Pennsylvania
| | - John McCauley
- Safety and Exploratory Pharmacology (J.W., H.Z., A.L.) and Discovery Chemistry (G.D., S.W., J.M.), Merck Research Laboratories, Merck & Co., Inc., West Point, Pennsylvania
| | - Armando Lagrutta
- Safety and Exploratory Pharmacology (J.W., H.Z., A.L.) and Discovery Chemistry (G.D., S.W., J.M.), Merck Research Laboratories, Merck & Co., Inc., West Point, Pennsylvania
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5
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Liu JY, Sayes CM. Modeling mixtures interactions in environmental toxicology. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2024; 106:104380. [PMID: 38309542 DOI: 10.1016/j.etap.2024.104380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 01/26/2024] [Accepted: 01/30/2024] [Indexed: 02/05/2024]
Abstract
In the environment, organisms are exposed to mixtures of different toxicants, which may interact in ways that are difficult to predict when only considering each component individually. Adapting and expanding tools from pharmacology, the toxicology field uses analytical, graphical, and computational methods to identify and quantify interactions in multi-component mixtures. The two general frameworks are concentration addition, where components have similar modes of action and their effects sum together, or independent action, where components have dissimilar modes of action and do not interact. Other interaction behaviors include synergism and antagonism, where the combined effects are more or less than the additive sum of individual effects. This review covers foundational theory, methods, an in-depth survey of original research from the past 20 years, current trends, and future directions. As humans and ecosystems are exposed to increasingly complex mixtures of environmental contaminants, analyzing mixtures interactions will continue to become a more critical aspect of toxicological research.
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Affiliation(s)
- James Y Liu
- Department of Environmental Science, Baylor University, Waco, TX, USA
| | - Christie M Sayes
- Department of Environmental Science, Baylor University, Waco, TX, USA.
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6
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In silico assessment on TdP risks of drug combinations under CiPA paradigm. Sci Rep 2023; 13:2924. [PMID: 36807374 PMCID: PMC9940090 DOI: 10.1038/s41598-023-29208-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Accepted: 01/31/2023] [Indexed: 02/22/2023] Open
Abstract
Researchers have recently proposed the Comprehensive In-vitro Proarrhythmia Assay (CiPA) to analyze medicines' TdP risks. Using the TdP metric known as qNet, numerous single-drug effects have been studied to classify the medications as low, intermediate, and high-risk. Furthermore, multiple medication therapies are recognized as a potential method for curing patients, mainly when limited drugs are available. This work expands the TdP risk assessment of drugs by introducing a CiPA-based in silico analysis of the TdP risk of combined drugs. The cardiac cell model was simulated using the population of models approach incorporating drug-drug interactions (DDIs) models on several ion channels for various drug pairs. Action potential duration (APD90), qNet, and calcium duration (CaD90) were computed and analyzed as biomarker features. The drug combination maps were also used to illustrate combined medicines' TdP risk. We found that the combined drugs alter cell responses in terms of biomarkers such as APD90, qNet, and CaD90 in a highly nonlinear manner. The results also revealed that combinations of high-risk with low-risk and intermediate-risk with low-risk drugs could result in compounds with varying TdP risks depending on the drug concentrations.
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7
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Yao X, Gao S, Wang J, Li Z, Huang J, Wang Y, Wang Z, Chen J, Fan X, Wang W, Jin X, Pan X, Yu Y, Lagrutta A, Yan N. Structural basis for the severe adverse interaction of sofosbuvir and amiodarone on L-type Ca v channels. Cell 2022; 185:4801-4810.e13. [PMID: 36417914 PMCID: PMC9891081 DOI: 10.1016/j.cell.2022.10.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Revised: 08/24/2022] [Accepted: 10/26/2022] [Indexed: 11/23/2022]
Abstract
Drug-drug interaction of the antiviral sofosbuvir and the antiarrhythmics amiodarone has been reported to cause fatal heartbeat slowing. Sofosbuvir and its analog, MNI-1, were reported to potentiate the inhibition of cardiomyocyte calcium handling by amiodarone, which functions as a multi-channel antagonist, and implicate its inhibitory effect on L-type Cav channels, but the molecular mechanism has remained unclear. Here we present systematic cryo-EM structural analysis of Cav1.1 and Cav1.3 treated with amiodarone or sofosbuvir alone, or sofosbuvir/MNI-1 combined with amiodarone. Whereas amiodarone alone occupies the dihydropyridine binding site, sofosbuvir is not found in the channel when applied on its own. In the presence of amiodarone, sofosbuvir/MNI-1 is anchored in the central cavity of the pore domain through specific interaction with amiodarone and directly obstructs the ion permeation path. Our study reveals the molecular basis for the physical, pharmacodynamic interaction of two drugs on the scaffold of Cav channels.
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Affiliation(s)
- Xia Yao
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA,These authors contribute equally
| | - Shuai Gao
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA,These authors contribute equally.,Present address: School of Pharmaceutical Sciences, TaiKang Center for Life and Medical Sciences, Wuhan University, Wuhan 430071, China,To whom correspondence should be addressed: N. Yan (); S. Gao ()
| | - Jixin Wang
- Department of Genetic and Cellular Toxicology, ADME & Discovery Toxicology, Preclinical Development, Merck Research Laboratories, Merck & Co., Inc., West Point, PA 19486, USA,These authors contribute equally
| | - Zhangqiang Li
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China,These authors contribute equally
| | - Jian Huang
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Yan Wang
- Department of Biological Sciences, St. John’s University, Queens, NY 11439, USA
| | - Zhifei Wang
- Department of Biological Sciences, St. John’s University, Queens, NY 11439, USA
| | - Jiaofeng Chen
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiao Fan
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Weipeng Wang
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xueqin Jin
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiaojing Pan
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yong Yu
- Department of Biological Sciences, St. John’s University, Queens, NY 11439, USA
| | - Armando Lagrutta
- Department of Genetic and Cellular Toxicology, ADME & Discovery Toxicology, Preclinical Development, Merck Research Laboratories, Merck & Co., Inc., West Point, PA 19486, USA
| | - Nieng Yan
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA,Lead contact.,To whom correspondence should be addressed: N. Yan (); S. Gao ()
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8
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Varaksin AN, Panov VG, Katsnelson BA, Minigalieva IA. Using Various Nonlinear Response Surfaces for Mathematical Description of the Type of Combined Toxicity. Dose Response 2018; 16:1559325818816596. [PMID: 30574029 PMCID: PMC6299322 DOI: 10.1177/1559325818816596] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 10/24/2018] [Accepted: 11/06/2018] [Indexed: 12/11/2022] Open
Abstract
The article considers the problem of characterizing the type of combined action produced by a mixture of toxic substances with the help of nonlinear response functions. Most attention is given to second-order models: the linear model with a cross-term and the quadratic model. General propositions are formulated based on the data on combined toxicity patterns previously obtained by the Ekaterinburg nanotoxicology team in animal experiments and analyzed with the help of the linear model with a cross-term. It is shown now that the quadratic model features these general characteristics in full measure, but interpretation of combined toxicity types based on isobolograms obtained by the quadratic model is more difficult. This suggests that where both models ensure a comparable quality of combined toxicity type identification, it would be enough to use the linear model with a cross-term.
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Affiliation(s)
- Anatoly N Varaksin
- Institute of Industrial Ecology of Ural Branch of Russian Academy of Sciences, Ekaterinburg, Russia
| | - Vladimir G Panov
- Institute of Industrial Ecology of Ural Branch of Russian Academy of Sciences, Ekaterinburg, Russia
| | - Boris A Katsnelson
- The Ekaterinburg Medical Research Center for Prophylaxis and Health Protection in Industrial Workers, Ekaterinburg, Russia
| | - Ilzira A Minigalieva
- The Ekaterinburg Medical Research Center for Prophylaxis and Health Protection in Industrial Workers, Ekaterinburg, Russia
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9
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Roweth HG, Yan R, Bedwani NH, Chauhan A, Fowler N, Watson AH, Malcor JD, Sage SO, Jarvis GE. Citalopram inhibits platelet function independently of SERT-mediated 5-HT transport. Sci Rep 2018; 8:3494. [PMID: 29472624 PMCID: PMC5823918 DOI: 10.1038/s41598-018-21348-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 02/01/2018] [Indexed: 11/09/2022] Open
Abstract
Citalopram prevents serotonin (5-HT) uptake into platelets by blocking the serotonin reuptake transporter (SERT). Although some clinical data suggest that selective serotonin reuptake inhibitors (SSRIs) may affect haemostasis and thrombosis, these poorly-characterised effects are not well understood mechanistically and useful in vitro data is limited. We sought to determine whether the inhibitory effects of citalopram on platelets are mediated via its pharmacological inhibition of 5-HT transport. We quantified the inhibitory potency of (RS)-, (R)- and (S)-citalopram on platelet function. If SERT blockade is the primary mechanism for citalopram-mediated platelet inhibition, these potencies should show quantitative congruence with inhibition of 5-HT uptake. Our data show that citalopram inhibits platelet aggregation, adhesion and thromboxane production with no difference in potency between (R)- and (S)-isomers. By contrast, citalopram had a eudysmic ratio of approximately 17 (S > R) for SERT blockade. Furthermore, nanomolar concentrations of citalopram inhibited 5-HT uptake into platelets but had no effect on other platelet functions, which were inhibited by micromolar concentrations. Our data indicate that citalopram-induced inhibition of platelets in vitro is not mediated by blockade of 5-HT transport. This raises a new question for future investigation: by what mechanism(s) does citalopram inhibit platelets?
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Affiliation(s)
- Harvey G Roweth
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, U.K
| | - Ruoling Yan
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, U.K
| | - Nader H Bedwani
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, U.K
| | - Alisha Chauhan
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, U.K
| | - Nicole Fowler
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, U.K
| | - Alice H Watson
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, U.K
| | | | - Stewart O Sage
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, U.K
| | - Gavin E Jarvis
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, U.K..
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10
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Wiśniowska B, Lisowski B, Kulig M, Polak S. Drug interaction at hERG channel: In vitro assessment of the electrophysiological consequences of drug combinations and comparison against theoretical models. J Appl Toxicol 2017; 38:450-458. [DOI: 10.1002/jat.3552] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 09/24/2017] [Accepted: 09/24/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Barbara Wiśniowska
- Pharmacoepidemiology and Pharmacoeconomics Unit, Faculty of Pharmacy; Jagiellonian University Medical College; Medyczna 9, Str., 30-688 Kraków Poland
| | - Bartosz Lisowski
- Pharmacoepidemiology and Pharmacoeconomics Unit, Faculty of Pharmacy; Jagiellonian University Medical College; Medyczna 9, Str., 30-688 Kraków Poland
- M. Smoluchowski Institute of Physics; Jagiellonian University; Kraków Poland
- Department of Biophysics; Jagiellonian University Medical College; Kraków Poland
| | - Magdalena Kulig
- Pharmacoepidemiology and Pharmacoeconomics Unit, Faculty of Pharmacy; Jagiellonian University Medical College; Medyczna 9, Str., 30-688 Kraków Poland
| | - Sebastian Polak
- Pharmacoepidemiology and Pharmacoeconomics Unit, Faculty of Pharmacy; Jagiellonian University Medical College; Medyczna 9, Str., 30-688 Kraków Poland
- Simcyp (part of Certara); S2 4SU Sheffield UK
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11
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Alberola-Die A, Fernández-Ballester G, González-Ros JM, Ivorra I, Morales A. Muscle-Type Nicotinic Receptor Modulation by 2,6-Dimethylaniline, a Molecule Resembling the Hydrophobic Moiety of Lidocaine. Front Mol Neurosci 2016; 9:127. [PMID: 27932949 PMCID: PMC5121239 DOI: 10.3389/fnmol.2016.00127] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 11/07/2016] [Indexed: 11/25/2022] Open
Abstract
To identify the molecular determinants responsible for lidocaine blockade of muscle-type nAChRs, we have studied the effects on this receptor of 2,6-dimethylaniline (DMA), which resembles lidocaine’s hydrophobic moiety. Torpedo marmorata nAChRs were microtransplanted to Xenopus oocytes and currents elicited by ACh (IACh), either alone or co-applied with DMA, were recorded. DMA reversibly blocked IACh and, similarly to lidocaine, exerted a closed-channel blockade, as evidenced by the enhancement of IACh blockade when DMA was pre-applied before its co-application with ACh, and hastened IACh decay. However, there were marked differences among its mechanisms of nAChR inhibition and those mediated by either the entire lidocaine molecule or diethylamine (DEA), a small amine resembling lidocaine’s hydrophilic moiety. Thereby, the IC50 for DMA, estimated from the dose-inhibition curve, was in the millimolar range, which is one order of magnitude higher than that for either DEA or lidocaine. Besides, nAChR blockade by DMA was voltage-independent in contrast to the increase of IACh inhibition at negative potentials caused by the more polar lidocaine or DEA molecules. Accordingly, virtual docking assays of DMA on nAChRs showed that this molecule binds predominantly at intersubunit crevices of the transmembrane-spanning domain, but also at the extracellular domain. Furthermore, DMA interacted with residues inside the channel pore, although only in the open-channel conformation. Interestingly, co-application of ACh with DEA and DMA, at their IC50s, had additive inhibitory effects on IACh and the extent of blockade was similar to that predicted by the allotopic model of interaction, suggesting that DEA and DMA bind to nAChRs at different loci. These results indicate that DMA mainly mimics the low potency and non-competitive actions of lidocaine on nAChRs, as opposed to the high potency and voltage-dependent block by lidocaine, which is emulated by the hydrophilic DEA. Furthermore, it is pointed out that the hydrophobic (DMA) and hydrophilic (DEA) moieties of the lidocaine molecule act differently on nAChRs and that their separate actions taken together account for most of the inhibitory effects of the whole lidocaine molecule on nAChRs.
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Affiliation(s)
- Armando Alberola-Die
- División de Fisiología, Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante Alicante, Spain
| | | | - José M González-Ros
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández Alicante, Spain
| | - Isabel Ivorra
- División de Fisiología, Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante Alicante, Spain
| | - Andrés Morales
- División de Fisiología, Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante Alicante, Spain
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12
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Gambierol and n-alkanols inhibit Shaker Kv channel via distinct binding sites outside the K(+) pore. Toxicon 2016; 120:57-60. [PMID: 27475861 DOI: 10.1016/j.toxicon.2016.07.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 07/21/2016] [Accepted: 07/26/2016] [Indexed: 01/14/2023]
Abstract
The marine polycyclic-ether toxin gambierol and 1-butanol (n-alkanol) inhibit Shaker-type Kv channels by interfering with the gating machinery. Competition experiments indicated that both compounds do not share an overlapping binding site but gambierol is able to affect 1-butanol affinity for Shaker through an allosteric effect. Furthermore, the Shaker-P475A mutant, which inverses 1-butanol effect, is inhibited by gambierol with nM affinity. Thus, gambierol and 1-butanol inhibit Shaker-type Kv channels via distinct parts of the gating machinery.
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13
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Jarvis GE, Barbosa R, Thompson AJ. Noncompetitive Inhibition of 5-HT3 Receptors by Citral, Linalool, and Eucalyptol Revealed by Nonlinear Mixed-Effects Modeling. J Pharmacol Exp Ther 2016; 356:549-62. [PMID: 26669427 PMCID: PMC5378937 DOI: 10.1124/jpet.115.230011] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/14/2015] [Indexed: 12/15/2022] Open
Abstract
Citral, eucalyptol, and linalool are widely used as flavorings, fragrances, and cosmetics. Here, we examined their effects on electrophysiological and binding properties of human 5-HT3 receptors expressed in Xenopus oocytes and human embryonic kidney 293 cells, respectively. Data were analyzed using nonlinear mixed-effects modeling to account for random variance in the peak current response between oocytes. The oils caused an insurmountable inhibition of 5-HT-evoked currents (citral IC50 = 120 µM; eucalyptol = 258 µM; linalool = 141 µM) and did not compete with fluorescently labeled granisetron, suggesting a noncompetitive mechanism of action. Inhibition was not use-dependent but required a 30-second preapplication. Compound washout caused a slow (∼180 seconds) but complete recovery. Coapplication of the oils with bilobalide or diltiazem indicated they did not bind at the same locations as these channel blockers. Homology modeling and ligand docking predicted binding to a transmembrane cavity at the interface of adjacent subunits. Liquid chromatography coupled to mass spectrometry showed that an essential oil extracted from Lippia alba contained 75.9% citral. This inhibited expressed 5-HT3 receptors (IC50 = 45 µg ml(-1)) and smooth muscle contractions in rat trachea (IC50 = 200 µg ml(-1)) and guinea pig ileum (IC50 = 20 µg ml(-1)), providing a possible mechanistic explanation for why this oil has been used to treat gastrointestinal and respiratory ailments. These results demonstrate that citral, eucalyptol, and linalool inhibit 5-HT3 receptors, and their binding to a conserved cavity suggests a valuable target for novel allosteric modulators.
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Affiliation(s)
- Gavin E Jarvis
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom (G.E.J.); Mestrado em Bioprospecção Molecular, Universidade Regional do Cariri, Crato, Brazil (R.B.); and Department of Pharmacology, Cambridge, United Kingdom (A.J.T.)
| | - Roseli Barbosa
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom (G.E.J.); Mestrado em Bioprospecção Molecular, Universidade Regional do Cariri, Crato, Brazil (R.B.); and Department of Pharmacology, Cambridge, United Kingdom (A.J.T.)
| | - Andrew J Thompson
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom (G.E.J.); Mestrado em Bioprospecção Molecular, Universidade Regional do Cariri, Crato, Brazil (R.B.); and Department of Pharmacology, Cambridge, United Kingdom (A.J.T.)
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Nazarov IB, Schofield CJ, Terrar DA. Contributions of cardiac "funny" (f) channels and sarcoplasmic reticulum Ca2+ in regulating beating rate of mouse and guinea pig sinoatrial node. Physiol Rep 2015; 3:3/12/e12561. [PMID: 26660545 PMCID: PMC4760437 DOI: 10.14814/phy2.12561] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The aim of this study was to investigate the effects on spontaneous beating rate of mouse atrial preparations following selective block of cardiac "funny" (f) channels, I(f), and/or suppression of sarcoplasmic reticulum (SR) function in the absence and presence of β-adrenoceptor stimulation. ZD7288 [to block I(f)] caused a substantial reduction (222 ± 13 bpm) in beating rate from 431 ± 14 to 209 ± 14 bpm, ryanodine alone (to block SR Ca(2+) release) reduced beating rate by 105 ± 11 bpm, with subsequent addition of ZD7288 further reducing rate by 57 ± 9 bpm. Cyclopiazonic acid (CPA) alone (to inhibit Ca(2+) reuptake by the SR) reduced beating rate by 148 ± 13 bpm with subsequent addition of ZD7288 further reducing rate by 79 ± 12 bpm. In additional experiments measuring Ca(2+) transients in the SA node region using Rhod-2, effects of ivabradine and ZD7288 on rate were again substantially reduced after CPA. Effects of CPA alone on rate developed much more slowly than effects on Ca(2+) transient amplitude. ZD7288, ivabradine, and CPA reduced the slope and maximum response of the log(concentration)-response curves for effects of isoprenaline on beating rate. Very little response to isoprenaline remained after treatment with CPA followed by ZD7288. Similar changes in isoprenaline log(concentration)-response curves were seen in guinea pig preparations. These observations are consistent with a role for Ca(2+) released from the SR in regulating I(f) and therefore beating rate of SA node preparations; there appear to be additional contributions of SR-derived Ca(2+) to effects of β-adrenoceptor stimulation on beating rate that are independent of I(f).
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Affiliation(s)
- Islom B Nazarov
- Department of Pharmacology, University of Oxford, Oxford, UK Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford, UK
| | | | - Derek A Terrar
- Department of Pharmacology, University of Oxford, Oxford, UK
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Alkanols inhibit voltage-gated K(+) channels via a distinct gating modifying mechanism that prevents gate opening. Sci Rep 2015; 5:17402. [PMID: 26616025 PMCID: PMC4663795 DOI: 10.1038/srep17402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 10/28/2015] [Indexed: 12/27/2022] Open
Abstract
Alkanols are small aliphatic compounds that inhibit voltage-gated K+ (Kv) channels through a yet unresolved gating mechanism. Kv channels detect changes in the membrane potential with their voltage-sensing domains (VSDs) that reorient and generate a transient gating current. Both 1-Butanol (1-BuOH) and 1-Hexanol (1-HeOH) inhibited the ionic currents of the Shaker Kv channel in a concentration dependent manner with an IC50 value of approximately 50 mM and 3 mM, respectively. Using the non-conducting Shaker-W434F mutant, we found that both alkanols immobilized approximately 10% of the gating charge and accelerated the deactivating gating currents simultaneously with ionic current inhibition. Thus, alkanols prevent the final VSD movement(s) that is associated with channel gate opening. Applying 1-BuOH and 1-HeOH to the Shaker-P475A mutant, in which the final gating transition is isolated from earlier VSD movements, strengthened that neither alkanol affected the early VSD movements. Drug competition experiments showed that alkanols do not share the binding site of 4-aminopyridine, a drug that exerts a similar effect at the gating current level. Thus, alkanols inhibit Shaker-type Kv channels via a unique gating modifying mechanism that stabilizes the channel in its non-conducting activated state.
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