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Körner J, Albani S, Sudha Bhagavath Eswaran V, Roehl AB, Rossetti G, Lampert A. Sodium Channels and Local Anesthetics-Old Friends With New Perspectives. Front Pharmacol 2022; 13:837088. [PMID: 35418860 PMCID: PMC8996304 DOI: 10.3389/fphar.2022.837088] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 02/16/2022] [Indexed: 12/11/2022] Open
Abstract
The long history of local anesthetics (LAs) starts out in the late 19th century when the content of coca plant leaves was discovered to alleviate pain. Soon after, cocaine was established and headed off to an infamous career as a substance causing addiction. Today, LAs and related substances-in modified form-are indispensable in our clinical everyday life for pain relief during and after minor and major surgery, and dental practices. In this review, we elucidate on the interaction of modern LAs with their main target, the voltage-gated sodium channel (Navs), in the light of the recently published channel structures. Knowledge of the 3D interaction sites of the drug with the protein will allow to mechanistically substantiate the comprehensive data available on LA gating modification. In the 1970s it was suggested that LAs can enter the channel pore from the lipid phase, which was quite prospective at that time. Today we know from cryo-electron microscopy structures and mutagenesis experiments, that indeed Navs have side fenestrations facing the membrane, which are likely the entrance for LAs to induce tonic block. In this review, we will focus on the effects of LA binding on fast inactivation and use-dependent inhibition in the light of the proposed new allosteric mechanism of fast inactivation. We will elaborate on subtype and species specificity and provide insights into modelling approaches that will help identify the exact molecular binding orientation, access pathways and pharmacokinetics. With this comprehensive overview, we will provide new perspectives in the use of the drug, both clinically and as a tool for basic ion channel research.
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Affiliation(s)
- Jannis Körner
- Institute of Physiology, Aachen, Germany.,Clinic of Anesthesiology, Medical Faculty, Uniklinik RWTH Aachen, Aachen, Germany
| | - Simone Albani
- Institute for Neuroscience and Medicine (INM-9/IAS-5), Forschungszentrum Jülich, Jülich, Germany.,Faculty of Mathematics, Computer Science and Natural Sciences, RWTH Aachen, Aachen, Germany
| | | | - Anna B Roehl
- Clinic of Anesthesiology, Medical Faculty, Uniklinik RWTH Aachen, Aachen, Germany
| | - Giulia Rossetti
- Institute for Neuroscience and Medicine (INM-9/IAS-5), Forschungszentrum Jülich, Jülich, Germany.,Jülich Supercomputing Center (JSC), Forschungszentrum Jülich, Aachen, Germany.,Department of Neurology, University Hospital Aachen, RWTH Aachen University, Aachen, Germany
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Structural basis for antiarrhythmic drug interactions with the human cardiac sodium channel. Proc Natl Acad Sci U S A 2019; 116:2945-2954. [PMID: 30728299 PMCID: PMC6386684 DOI: 10.1073/pnas.1817446116] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Voltage-gated sodium channels play a central role in cellular excitability and are key targets for drug development. Recent breakthroughs in high-resolution cryo-electron microscopy protein structure determination, Rosetta computational protein structure modeling, and multimicrosecond molecular dynamics simulations are empowering advances in structural biology to study the atomistic details of channel−drug interactions. We used Rosetta structural computational modeling and molecular dynamics simulations to study the interactions of antiarrhythmic and local anesthetic drugs with cardiac sodium channel. Our results provide crucial atomic-scale mechanistic insights into the channel–drug interactions, necessary for the rational design of novel modulators of the human cardiac sodium channel to be used for the treatment of cardiac arrhythmias. The human voltage-gated sodium channel, hNaV1.5, is responsible for the rapid upstroke of the cardiac action potential and is target for antiarrhythmic therapy. Despite the clinical relevance of hNaV1.5-targeting drugs, structure-based molecular mechanisms of promising or problematic drugs have not been investigated at atomic scale to inform drug design. Here, we used Rosetta structural modeling and docking as well as molecular dynamics simulations to study the interactions of antiarrhythmic and local anesthetic drugs with hNaV1.5. These calculations revealed several key drug binding sites formed within the pore lumen that can simultaneously accommodate up to two drug molecules. Molecular dynamics simulations identified a hydrophilic access pathway through the intracellular gate and a hydrophobic access pathway through a fenestration between DIII and DIV. Our results advance the understanding of molecular mechanisms of antiarrhythmic and local anesthetic drug interactions with hNaV1.5 and will be useful for rational design of novel therapeutics.
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Sofiyev V, Kaur H, Snyder BA, Hogan PA, Ptak RG, Hwang P, Gochin M. Enhanced potency of bivalent small molecule gp41 inhibitors. Bioorg Med Chem 2017; 25:408-420. [PMID: 27908751 PMCID: PMC5260928 DOI: 10.1016/j.bmc.2016.11.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 10/31/2016] [Accepted: 11/03/2016] [Indexed: 11/28/2022]
Abstract
Low molecular weight peptidomimetic inhibitors with hydrophobic pocket binding properties and moderate fusion inhibitory activity against HIV-1 gp41-mediated cell fusion were elaborated by increasing the available surface area for interacting with the heptad repeat-1 (HR1) coiled coil on gp41. Two types of modifications were tested: 1) increasing the overall hydrophobicity of the molecules with an extension that could interact in the HR1 groove, and 2) forming symmetrical dimers with two peptidomimetic motifs that could potentially interact simultaneously in two hydrophobic pockets on the HR1 trimer. The latter approach was more successful, yielding 40-60times improved potency against HIV fusion over the monomers. Biophysical characterization, including equilibrium binding studies by fluorescence and kinetic analysis by Surface Plasmon Resonance, revealed that inhibitor potency was better correlated to off-rates than to binding affinity. Binding and kinetic data could be fit to a model of bidentate interaction of dimers with the HR1 trimer as an explanation for the slow off-rate, albeit with minimal cooperativity due to the highly flexible ligand structures. The strong cooperativity observed in fusion inhibitory activity of the dimers implied accentuated potency due to the transient nature of the targeted intermediate. Optimization of monomer, dimer or higher order structures has the potential to lead to highly potent non-peptide fusion inhibitors by targeting multiple hydrophobic pockets.
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Affiliation(s)
- Vladimir Sofiyev
- Department of Basic Sciences, Touro University-California, Vallejo, CA 94592, United States
| | - Hardeep Kaur
- Department of Basic Sciences, Touro University-California, Vallejo, CA 94592, United States
| | - Beth A Snyder
- Southern Research Institute, 431 Aviation Way, Frederick, MD 21701, United States
| | - Priscilla A Hogan
- Southern Research Institute, 431 Aviation Way, Frederick, MD 21701, United States
| | - Roger G Ptak
- Southern Research Institute, 431 Aviation Way, Frederick, MD 21701, United States
| | - Peter Hwang
- Department of Biophysics and Biochemistry, University of California San Francisco, CA 94143, United States
| | - Miriam Gochin
- Department of Basic Sciences, Touro University-California, Vallejo, CA 94592, United States; Department of Pharmaceutical Chemistry, University of California San Francisco, CA 94143, United States.
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Murray JK, Biswas K, Holder JR, Zou A, Ligutti J, Liu D, Poppe L, Andrews KL, Lin FF, Meng SY, Moyer BD, McDonough SI, Miranda LP. Sustained inhibition of the Na V 1.7 sodium channel by engineered dimers of the domain II binding peptide GpTx-1. Bioorg Med Chem Lett 2015; 25:4866-4871. [DOI: 10.1016/j.bmcl.2015.06.033] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 06/06/2015] [Accepted: 06/08/2015] [Indexed: 11/15/2022]
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Lazar A, Lenkey N, Pesti K, Fodor L, Mike A. Different pH-sensitivity patterns of 30 sodium channel inhibitors suggest chemically different pools along the access pathway. Front Pharmacol 2015; 6:210. [PMID: 26441665 PMCID: PMC4585259 DOI: 10.3389/fphar.2015.00210] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 09/08/2015] [Indexed: 11/28/2022] Open
Abstract
The major drug binding site of sodium channels is inaccessible from the extracellular side, drug molecules can only access it either from the membrane phase, or from the intracellular aqueous phase. For this reason, ligand-membrane interactions are as important determinants of inhibitor properties, as ligand-protein interactions. One-way to probe this is to modify the pH of the extracellular fluid, which alters the ratio of charged vs. uncharged forms of some compounds, thereby changing their interaction with the membrane. In this electrophysiology study we used three different pH values: 6.0, 7.3, and 8.6 to test the significance of the protonation-deprotonation equilibrium in drug access and affinity. We investigated drugs of several different indications: carbamazepine, lamotrigine, phenytoin, lidocaine, bupivacaine, mexiletine, flecainide, ranolazine, riluzole, memantine, ritanserin, tolperisone, silperisone, ambroxol, haloperidol, chlorpromazine, clozapine, fluoxetine, sertraline, paroxetine, amitriptyline, imipramine, desipramine, maprotiline, nisoxetine, mianserin, mirtazapine, venlafaxine, nefazodone, and trazodone. We recorded the pH-dependence of potency, reversibility, as well as onset/offset kinetics. As expected, we observed a strong correlation between the acidic dissociation constant (pKa) of drugs and the pH-dependence of their potency. Unexpectedly, however, the pH-dependence of reversibility or kinetics showed diverse patterns, not simple correlation. Our data are best explained by a model where drug molecules can be trapped in at least two chemically different environments: A hydrophilic trap (which may be the aqueous cavity within the inner vestibule), which favors polar and less lipophilic compounds, and a lipophilic trap (which may be the membrane phase itself, and/or lipophilic binding sites on the channel). Rescue from the hydrophilic and lipophilic traps can be promoted by alkalic and acidic extracellular pH, respectively.
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Affiliation(s)
- Alexandra Lazar
- Intensive Care Unit, University of Medicine and Pharmacy Tirgu Mures, Romania
| | - Nora Lenkey
- Lendület Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Krisztina Pesti
- Opto-Neuropharmacology Group, MTA-ELTE NAP B Budapest, Hungary ; János Szentágothai Doctoral School of Neurosciences, Semmelweis University Budapest, Hungary
| | - Laszlo Fodor
- Pharmacology and Drug Safety Research, Gedeon Richter Plc. Budapest, Hungary
| | - Arpad Mike
- Opto-Neuropharmacology Group, MTA-ELTE NAP B Budapest, Hungary
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Tsuruda PR, Vickery RG, Long DD, Armstrong SR, Beattie DT. The in vitro pharmacological profile of TD-1211, a neutral opioid receptor antagonist. Naunyn Schmiedebergs Arch Pharmacol 2013; 386:479-91. [DOI: 10.1007/s00210-013-0850-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 03/06/2013] [Indexed: 01/02/2023]
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Bohlen CJ, Julius D. Receptor-targeting mechanisms of pain-causing toxins: How ow? Toxicon 2012; 60:254-64. [PMID: 22538196 DOI: 10.1016/j.toxicon.2012.04.336] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 04/04/2012] [Indexed: 12/15/2022]
Abstract
Venoms often target vital processes to cause paralysis or death, but many types of venom also elicit notoriously intense pain. While these pain-producing effects can result as a byproduct of generalized tissue trauma, there are now multiple examples of venom-derived toxins that target somatosensory nerve terminals in order to activate nociceptive (pain-sensing) neural pathways. Intriguingly, investigation of the venom components that are responsible for evoking pain has revealed novel roles and/or configurations of well-studied toxin motifs. This review serves to highlight pain-producing toxins that target the capsaicin receptor, TRPV1, or members of the acid-sensing ion channel family, and to discuss the utility of venom-derived multivalent and multimeric complexes.
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Affiliation(s)
- Christopher J Bohlen
- Department of Physiology, University of California, San Francisco, CA 94158-2517, USA.
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Ma D, Glassenberg R, Ghosh S, Zavalij PY, Isaacs L. Acyclic cucurbituril congener binds to local anaesthetics. Supramol Chem 2012. [DOI: 10.1080/10610278.2012.658394] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Da Ma
- a Department of Chemistry and Biochemistry , University of Maryland , College Park , MD , 20742 , USA
| | - Raymond Glassenberg
- b Department of Anesthesiology , Feinberg School of Medicine, Northwestern University , Chicago , IL , 60611 , USA
| | - Soumyadip Ghosh
- a Department of Chemistry and Biochemistry , University of Maryland , College Park , MD , 20742 , USA
| | - Peter Y. Zavalij
- a Department of Chemistry and Biochemistry , University of Maryland , College Park , MD , 20742 , USA
| | - Lyle Isaacs
- a Department of Chemistry and Biochemistry , University of Maryland , College Park , MD , 20742 , USA
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Beattie DT, Armstrong SR, Vickery RG, Tsuruda PR, Campbell CB, Richardson C, McCullough JL, Daniels O, Kersey K, Li YP, Kim KHS. The Pharmacology of TD-8954, a Potent and Selective 5-HT(4) Receptor Agonist with Gastrointestinal Prokinetic Properties. Front Pharmacol 2011; 2:25. [PMID: 21687517 PMCID: PMC3108484 DOI: 10.3389/fphar.2011.00025] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Accepted: 05/16/2011] [Indexed: 12/12/2022] Open
Abstract
This study evaluated the in vitro and in vivo pharmacological properties of TD-8954, a potent and selective 5-HT(4) receptor agonist. TD-8954 had high affinity (pK(i) = 9.4) for human recombinant 5-HT(4(c)) (h5-HT(4(c))) receptors, and selectivity (>2,000-fold) over all other 5-hydroxytryptamine (5-HT) receptors and non-5-HT receptors, ion channels, enzymes and transporters tested (n = 78). TD-8954 produced an elevation of cAMP in HEK-293 cells expressing the h5-HT(4(c)) receptor (pEC(50) = 9.3), and contracted the guinea pig colonic longitudinal muscle/myenteric plexus preparation (pEC(50) = 8.6). TD-8954 had moderate intrinsic activity in the in vitro assays. In conscious guinea pigs, subcutaneous administration of TD-8954 (0.03-3 mg/kg) increased the colonic transit of carmine red dye, reducing the time taken for its excretion. Following intraduodenal dosing to anesthetized rats, TD-8954 (0.03-10 mg/kg) evoked a dose-dependent relaxation of the esophagus. Following oral administration to conscious dogs, TD-8954 (10 and 30 μg/kg) produced an increase in contractility of the antrum, duodenum, and jejunum. In a single ascending oral dose study in healthy human subjects, TD-8954 (0.1-20 mg) increased bowel movement frequency and reduced the time to first stool. It is concluded that TD-8954 is a potent and selective 5-HT(4) receptor agonist in vitro, with robust in vivo stimulatory activity in the gastrointestinal (GI) tract of guinea pigs, rats, dogs, and humans. TD-8954 may have clinical utility in patients with disorders of reduced GI motility.
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Affiliation(s)
- David T. Beattie
- Department of Pharmacology, Theravance, Inc.South San Francisco, CA, USA
| | - Scott R. Armstrong
- Department of Pharmacology, Theravance, Inc.South San Francisco, CA, USA
| | - Ross G. Vickery
- Department of Clinical Pharmacology and Experimental Medicine, Theravance, Inc.South San Francisco, CA, USA
| | - Pamela R. Tsuruda
- Department of Molecular and Cellular Biology, Theravance, Inc.South San Francisco, CA, USA
| | | | | | | | - Oranee Daniels
- Department of Clinical Pharmacology and Experimental Medicine, Theravance, Inc.South San Francisco, CA, USA
| | - Kathryn Kersey
- Department of Clinical Pharmacology and Experimental Medicine, Theravance, Inc.South San Francisco, CA, USA
| | - Yu-Ping Li
- Department of Biometrics, Theravance, Inc.South San Francisco, CA, USA
| | - Karl H. S. Kim
- Department of Clinical Pharmacology and Experimental Medicine, Theravance, Inc.South San Francisco, CA, USA
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Lenkey N, Karoly R, Lukacs P, Vizi ES, Sunesen M, Fodor L, Mike A. Classification of drugs based on properties of sodium channel inhibition: a comparative automated patch-clamp study. PLoS One 2010; 5:e15568. [PMID: 21187965 PMCID: PMC3004914 DOI: 10.1371/journal.pone.0015568] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Accepted: 11/15/2010] [Indexed: 01/28/2023] Open
Abstract
Background There is only one established drug binding site on sodium channels. However, drug binding of sodium channels shows extreme promiscuity: ∼25% of investigated drugs have been found to potently inhibit sodium channels. The structural diversity of these molecules suggests that they may not share the binding site, and/or the mode of action. Our goal was to attempt classification of sodium channel inhibitors by measuring multiple properties of inhibition in electrophysiology experiments. We also aimed to investigate if different properties of inhibition correlate with specific chemical properties of the compounds. Methodology/Principal Findings A comparative electrophysiological study of 35 compounds, including classic sodium channel inhibitors (anticonvulsants, antiarrhythmics and local anesthetics), as well as antidepressants, antipsychotics and neuroprotective agents, was carried out using rNav1.2 expressing HEK-293 cells and the QPatch automatic patch-clamp instrument. In the multi-dimensional space defined by the eight properties of inhibition (resting and inactivated affinity, potency, reversibility, time constants of onset and offset, use-dependence and state-dependence), at least three distinct types of inhibition could be identified; these probably reflect distinct modes of action. The compounds were clustered similarly in the multi-dimensional space defined by relevant chemical properties, including measures of lipophilicity, aromaticity, molecular size, polarity and electric charge. Drugs of the same therapeutic indication typically belonged to the same type. We identified chemical properties, which were important in determining specific properties of inhibition. State-dependence correlated with lipophilicity, the ratio of the neutral form of molecules, and aromaticity: We noticed that the highly state dependent inhibitors had at least two aromatic rings, logP>4.0, and pKa<8.0. Conclusions/Significance The correlations of inhibition properties both with chemical properties and therapeutic profiles would not have been evident through the sole determination of IC50; therefore, recording multiple properties of inhibition may allow improved prediction of therapeutic usefulness.
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Affiliation(s)
- Nora Lenkey
- Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Robert Karoly
- Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Peter Lukacs
- Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - E. Sylvester Vizi
- Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | | | - Laszlo Fodor
- Pharmacology and Drug Safety Research, Gedeon Richter Plc., Budapest, Hungary
| | - Arpad Mike
- Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- * E-mail:
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Steinfeld T, Hughes AD, Klein U, Smith JAM, Mammen M. THRX-198321 is a bifunctional muscarinic receptor antagonist and beta2-adrenoceptor agonist (MABA) that binds in a bimodal and multivalent manner. Mol Pharmacol 2010; 79:389-99. [PMID: 21139051 DOI: 10.1124/mol.110.069120] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Biphenyl-2-yl-carbamic acid 1-{9-[(R)-2-hydroxy-2-(8-hydroxy-2-oxo-1,2-dihydro-quinolin-5-yl)-ethylamino]-nonyl}-piperidin-4-yl ester (THRX-198321) is a single molecule composed of a muscarinic acetylcholine receptor (mAChR) antagonist moiety, represented by the fragment MA, linked by a C9 polymethylene chain to a β(2)-adrenoceptor (β(2)AR) agonist moiety, represented by the fragment 8-hydroxy-5-((R)-1-hydroxy-2-methylamino-ethyl)-1H-quinolin-2-one (BA). THRX-198321 exhibited high affinity for mAChR (M(2) pK(I,App) = 10.57 ± 0.09; M(3) pK(I,App) = 10.07 ± 0.11) and β(2)AR (pK(I,App) = 9.54 ± 0.15), with potent mAChR antagonist (M(2) pK(I,Fn) = 9.69 ± 0.23; M(3) pK(I,Fn) = 10.05 ± 0.17) and β(2)AR agonist (pEC(50) = 9.25 ± 0.02) activities. Consistent with multivalent interactions, THRX-198321 binding affinity was >300-fold higher at mAChR and 29-fold higher at β(2)AR relative to its monovalent fragments biphenyl carbamic acid piperidinyl ester (MA) and BA, respectively. THRX-198321 was a competitive antagonist at mAChR (M(2) pK(B) = 9.98 ± 0.13; M(3) pK(B) = 10.31 ± 0.89), whereas THRX-198321 agonist activity at β(2)AR was competitively inhibited by propranolol. Interactions of THRX-198321 with an allosteric site on mAChR and a novel extracellular allosteric site on β(2)AR, respectively, were detected by measuring THRX-198321-evoked changes in the dissociation rates for the orthosteric radioligands, [N-methyl-(3)H]scopolamine methyl chloride (M(2) pEC(50,diss) = 6.73 ± 0.10; M(3) pEC(50,diss) = 5.02 ± 0.14) and [4,6-propyl-(3)H]dihydroalprenolol (β(2)AR pEC(50,diss) = 3.82 ± 0.25). The carbostyril-linker fragment (BA-L) binds to the allosteric site of mAChR (M(2) pEC(50,diss) = 5.06 ± 0.03; M(3) pEC(50,diss) = 4.15 ± 0.25), whereas the MA fragment binds to the allosteric site of β(2)AR (pEC(50,diss) = 3.60 ± 0.18). Collectively, these observations suggest that THRX-198321 exhibits a multivalent bimodal orientation in the orthosteric and allosteric binding pockets of mAChR and β(2)AR, a phenomenon that may be unique to this class of molecule.
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Affiliation(s)
- Tod Steinfeld
- Department of Molecular and Cellular Biology, Theravance, Inc., South San Francisco, CA 94080, USA.
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Smith JAM, Beattie DT, Marquess D, Shaw JP, Vickery RG, Humphrey PPA. The in vitro pharmacological profile of TD-5108, a selective 5-HT(4) receptor agonist with high intrinsic activity. Naunyn Schmiedebergs Arch Pharmacol 2008; 378:125-37. [PMID: 18415081 DOI: 10.1007/s00210-008-0282-y] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2007] [Accepted: 03/03/2008] [Indexed: 12/17/2022]
Abstract
The in vitro pharmacological profile of TD-5108, a novel, selective 5-HT(4) receptor agonist, was compared to that of clinically efficacious gastroprokinetic 5-HT(4) receptor agonists. TD-5108 produced an elevation of cyclic adenosine monophosphate in human embryonic kidney 293 cells expressing the human recombinant 5-HT(4(c)) (h5-HT(4(c))) receptor (pEC(50) = 8.3) and 5-HT(4) receptor-mediated relaxation of the rat esophagus (pEC(50) = 7.9) and contraction of the guinea pig colon (pEC(50) = 7.9). In all in vitro assays, TD-5108 was a high intrinsic activity agonist, unlike tegaserod, mosapride, and cisapride which, in the majority of test systems, had lower intrinsic activity. TD-5108 had high affinity (pK (i) = 7.7) and selectivity (> or =25-fold) for h5-HT(4(c)) receptors over other biogenic amine receptors. TD-5108 was >500-fold selective over other 5-HT receptors (including h5-HT(2B) and h5-HT(3A)) and, at 3 microM, had no effect on human ether-à-go-go-related gene K+ channels. In conclusion, TD-5108 is a selective 5-HT(4) receptor agonist in vitro. The high intrinsic activity and preferential binding of TD-5108 to 5-HT4 over other 5-HT receptors may result in an improved clinical profile for the treatment of gastrointestinal disorders of reduced motility.
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Affiliation(s)
- J A M Smith
- Theravance, Inc., 901 Gateway Boulevard, South San Francisco, CA, 94080, USA.
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Steinfeld T, Mammen M, Smith JAM, Wilson RD, Jasper JR. A novel multivalent ligand that bridges the allosteric and orthosteric binding sites of the M2 muscarinic receptor. Mol Pharmacol 2007; 72:291-302. [PMID: 17478612 DOI: 10.1124/mol.106.033746] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
THRX-160209 is a potent antagonist at the M(2) muscarinic acetylcholine (ACh) receptor subtype that was designed using a multivalent strategy, simultaneously targeting the orthosteric site and a nearby site known to bind allosteric ligands. In this report, we describe three characteristics of THRX-160209 binding that are consistent with a multivalent interaction: 1) an apparent affinity of the multivalent ligand for the M2 receptor subtype (apparent pK(I) = 9.51 +/- 0.22) that was several orders of magnitude greater than its two monovalent components (apparent pK(I) values < 6.0), 2) specificity of THRX-160209 for the M2 receptor subtype compared with the closely related M4 (apparent pK(I) = 8.78 +/- 0.24) and M1, M3, and M5 receptors (apparent pK(I) values <or= 8.0), and 3) acceleration (>10-fold) of the dissociation rate of tritium-labeled THRX-160209 from M2 receptors by competing monovalent ligands that are known to interact with either the orthosteric site (e.g., atropine) or a well characterized allosteric site (e.g., obidoxime) on the receptor. In complementary kinetic studies assessing allosteric modulation of the receptor, unlabeled THRX-160209 retarded dissociation of [3H]N-methyl scopolamine (NMS). The effects of THRX-160209 on retardation of [3H]NMS dissociation were competitively inhibited by obidoxime, suggesting that obidoxime and THRX-160209 bind to an overlapping region coincident with other typical muscarinic allosteric agents, such as 3-methyl-5-[7-[4-[(4S)-4-methyl-1,3-oxazolidin-2-yl]phenoxy]heptyl]-1,2-oxazole (W84) and gallamine. Taken together, these data are consistent with the hypothesis that THRX-160209 binds in a multivalent manner to the M2 receptor, simultaneously occupying the orthosteric site and a spatially distinct allosteric site.
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Affiliation(s)
- Tod Steinfeld
- Department of Molecular and Cellular Biology, Theravance, Inc., 901 Gateway Blvd, South San Francisco, California, USA.
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Trellakis S, Lautermann J, Lehnerdt G. Lidocaine: neurobiological targets and effects on the auditory system. PROGRESS IN BRAIN RESEARCH 2007; 166:303-22. [DOI: 10.1016/s0079-6123(07)66028-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Wang SY, Mitchell J, Wang GK. Preferential block of inactivation-deficient Na+ currents by capsaicin reveals a non-TRPV1 receptor within the Na+ channel. Pain 2006; 127:73-83. [PMID: 16962240 PMCID: PMC1995448 DOI: 10.1016/j.pain.2006.08.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2006] [Revised: 07/27/2006] [Accepted: 08/01/2006] [Indexed: 01/07/2023]
Abstract
Capsaicin elicits burning pain via the activation of the vanilloid receptor (TRPV1). Intriguingly, several reports showed that capsaicin also inhibits Na+ currents but the mechanisms remain unclear. To explore this non-TRPV1 action we applied capsaicin to HEK293 cells stably expressing inactivation-deficient rat skeletal muscle Na+ mutant channels (rNav1.4-WCW). Capsaicin elicited a conspicuous time-dependent block of inactivation-deficient Na+ currents. The 50% inhibitory concentration (IC50) of capsaicin for open Na+ channels at +30 mV was measured 6.8+/-0.6 microM (n=5), a value that is 10-30 times lower than those for resting (218 microM) and inactivated (74 microM) wild-type Na+ channels. On-rate and off-rate constants for capsaicin open-channel block at +30 mV were estimated to be 6.37 microM(-1) s(-1) and 34.4 s(-1), respectively, with a calculated dissociation constant (KD) of 5.4 microM. Capsaicin at 30 microM produced approximately 70% additional use-dependent block of remaining rNav1.4-WCW Na+ currents during repetitive pulses at 1 Hz. Site-directed mutagenesis showed that the local anesthetic receptor was not responsible for the capsaicin block of the inactivation-deficient Na+ channel. Interestingly, capsaicin elicited little time-dependent block of batrachotoxin-modified rNav1.4-WCW Na+ currents, indicating that batrachotoxin prevents capsaicin binding. Finally, neuronal open Na+ channels endogenously expressed in GH3 cells were as sensitive to capsaicin block as rNav1.4 counterparts. We conclude that capsaicin preferentially blocks persistent late Na+ currents, probably via a receptor that overlaps the batrachotoxin receptor but not the local anesthetic receptor. Drugs that target such a non-TRPV1 receptor could be beneficial for patients with neuropathic pain.
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Affiliation(s)
- Sho-Ya Wang
- Department of Biology, State University of New York at Albany, Albany, NY, United States
| | - Jane Mitchell
- Department of Anesthesia, Harvard Medical School and Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115, United States
| | - Ging Kuo Wang
- Department of Anesthesia, Harvard Medical School and Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115, United States
- *Corresponding author. Tel.: +1 617732 6886; fax: +1 617730 2801. E-mail address: (G.K. Wang)
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