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van Bon BWM, Gilissen C, Grange DK, Hennekam RCM, Kayserili H, Engels H, Reutter H, Ostergaard JR, Morava E, Tsiakas K, Isidor B, Le Merrer M, Eser M, Wieskamp N, de Vries P, Steehouwer M, Veltman JA, Robertson SP, Brunner HG, de Vries BBA, Hoischen A. Cantú syndrome is caused by mutations in ABCC9. Am J Hum Genet 2012; 90:1094-101. [PMID: 22608503 DOI: 10.1016/j.ajhg.2012.04.014] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 04/12/2012] [Accepted: 04/20/2012] [Indexed: 01/08/2023] Open
Abstract
Cantú syndrome is a rare disorder characterized by congenital hypertrichosis, neonatal macrosomia, a distinct osteochondrodysplasia, and cardiomegaly. Using an exome-sequencing approach applied to one proband-parent trio and three unrelated single cases, we identified heterozygous mutations in ABCC9 in all probands. With the inclusion of the remaining cohort of ten individuals with Cantú syndrome, a total of eleven mutations in ABCC9 were found. The de novo occurrence in all six simplex cases in our cohort substantiates the presence of a dominant disease mechanism. All mutations were missense, and several mutations affect Arg1154. This mutation hot spot lies within the second type 1 transmembrane region of this ATP-binding cassette transporter protein, which may suggest an activating mutation. ABCC9 encodes the sulfonylurea receptor (SUR) that forms ATP-sensitive potassium channels (K(ATP) channels) originally shown in cardiac, skeletal, and smooth muscle. Previously, loss-of-function mutations in this gene have been associated with idiopathic dilated cardiomyopathy type 10 (CMD10). These findings identify the genetic basis of Cantú syndrome and suggest that this is a new member of the potassium channelopathies.
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Affiliation(s)
- Bregje W M van Bon
- Department of Human Genetics, Nijmegen Centre for Molecular Life Sciences, The Netherlands
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2
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Winkler M, Kühner P, Russ U, Ortiz D, Bryan J, Quast U. Role of the amino-terminal transmembrane domain of sulfonylurea receptor SUR2B for coupling to KIR6.2, ligand binding, and oligomerization. Naunyn Schmiedebergs Arch Pharmacol 2011; 385:287-98. [DOI: 10.1007/s00210-011-0708-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 10/24/2011] [Indexed: 01/11/2023]
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3
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Amann T, Schell S, Kühner P, Winkler M, Schwanstecher M, Russ U, Quast U. Substitution of the Walker A lysine by arginine in the nucleotide-binding domains of sulphonylurea receptor SUR2B: effects on ligand binding and channel activity. Naunyn Schmiedebergs Arch Pharmacol 2010; 381:507-16. [PMID: 20352196 DOI: 10.1007/s00210-010-0510-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Accepted: 02/28/2010] [Indexed: 10/19/2022]
Abstract
Sulphonylurea receptors (SURs) serve as regulatory subunits of ATP-sensitive K(+) channels. SURs are members of the ATP-binding cassette (ABC) protein superfamily and contain two conserved nucleotide-binding domains (NBDs) which bind and hydrolyse MgATP; in addition, they carry the binding sites for the sulphonylureas like glibenclamide (GBC) which close the channel and for the K(ATP) channel openers such as P1075. Here we have exchanged the conserved Lys in the Walker A motif by Arg in both NBDs of SUR2B, the regulatory subunit of the vascular K(ATP) channel. Then the effect of the mutation on the ATPase-dependent binding of GBC and P1075 to SUR2B and on the activity of the recombinant vascular (Kir6.1/SUR2B) channel was assessed. Surprisingly, in the absence of MgATP, the mutation weakened binding of P1075 and the extent of allosteric inhibition of GBC binding by P1075. The mutation abolished most, but not all, of the MgATP effects on the binding of GBC and P1075 and prevented nucleotide-induced activation of the channel which relies on SUR reaching the posthydrolytic (MgADP-bound) state; the mutant channel was, however, opened by P1075 at higher concentrations. The data provide evidence that mutant SUR2B binds MgATP but that the posthydrolytic state is insufficiently populated. This suggests that the mutation locks SUR2B in an MgATP-binding prehydrolytic-like state; binding of P1075 may induce a posthydrolytic-like conformation to open the channel.
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Affiliation(s)
- Tobias Amann
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard-Karls-University Hospitals and Clinics, University of Tübingen, Wilhelmstr. 56, 72074, Tübingen, Germany
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Cao R, Higashikubo BT, Cardin J, Knoblich U, Ramos R, Nelson MT, Moore CI, Brumberg JC. Pinacidil induces vascular dilation and hyperemia in vivo and does not impact biophysical properties of neurons and astrocytes in vitro. Cleve Clin J Med 2009; 76 Suppl 2:S80-5. [PMID: 19380306 DOI: 10.3949/ccjm.76.s2.16] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Vascular and neural systems are highly interdependent, as evidenced by the wealth of intrinsic modulators shared by the two systems. We tested the hypothesis that pinacidil, a selective agonist for the SUR2B receptor found on smooth muscles, could serve as an independent means of inducing vasodilation and increased local blood volume to emulate functional hyperemia. Application of pinacidil induced vasodilation and increased blood volume in the in vivo neocortex in anesthetized rats and awake mice. Direct application of this agent to the in vitro neocortical slice had no direct impact on biophysical properties of neurons or astrocytes assessed with whole-cell recording. These findings suggest that pinacidil provides an effective and selective means for inducing hyperemia in vivo, and may provide a useful tool in directly testing the impact of hemodynamics on neural activity, as recently predicted by the hemo-neural hypothesis.
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Affiliation(s)
- Rosa Cao
- Massachusetts Institute of Technology, Department of Brain and Cognitive Sciences, Building 46-2171, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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Abstract
Understanding the molecular mechanisms underlying synergistic, potentiative and antagonistic effects of drug combinations could facilitate the discovery of novel efficacious combinations and multi-targeted agents. In this article, we describe an extensive investigation of the published literature on drug combinations for which the combination effect has been evaluated by rigorous analysis methods and for which relevant molecular interaction profiles of the drugs involved are available. Analysis of the 117 drug combinations identified reveals general and specific modes of action, and highlights the potential value of molecular interaction profiles in the discovery of novel multicomponent therapies.
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Jilkina O, Kuzio B, Kupriyanov VV. Potassium fluxes, energy metabolism, and oxygenation in intact diabetic rat hearts under normal and stress conditions. Can J Physiol Pharmacol 2008; 86:710-25. [DOI: 10.1139/y08-076] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We evaluated the function of Na+/K+ATPase and sarcolemmal KATPchannels in diabetic rat hearts. Six weeks after streptozotocin (STZ) injection, unidirectional K+fluxes were assayed by using87rubidium (87Rb+) MRS. The hearts were loaded with Rb+by perfusion with Krebs–Henseleit buffer, in which 50% of K+was substituted with Rb+. The rate constant of Rb+uptake via Na+/K+ATPase was reduced. KATP-mediated Rb+efflux was activated metabolically with 2,4-dinitrophenol (DNP, 50 µmol·L–1) or pharmacologically with a KATPchannel opener, P-1075 (5 µmol·L–1). Cardiac energetics were monitored by using31P MRS and optical spectroscopy. DNP produced a smaller ATP decrease, yet similar Rb+efflux activation in STZ hearts. In K+-arrested hearts, P-1075 had no effect on high-energy phosphates and stimulated Rb+efflux by interaction with SUR2A subunit of KATPchannel; this stimulation was greater in STZ hearts. In normokalemic hearts, P-1075 caused cardiac arrest and ATP decline, and the stimulation of Rb+efflux was lower in normokalemic STZ hearts arrested by P-1075. Thus, the Rb+efflux stimulation in STZ hearts was altered depending on the mode of KATPchannel activation: pharmacologic stimulation (P-1075) was enhanced, whereas metabolic stimulation (DNP) was reduced. Both the basal concentration of phosphocreatine ([PCr]) and [PCr]/[ATP] were reduced; nevertheless, the STZ hearts were more or equally resistant to metabolic stress.
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Affiliation(s)
- Olga Jilkina
- Institute for Biodiagnostics, National Research Council of Canada, 435 Ellice Avenue, Winnipeg, MB R3B 1Y6, Canada
- Department of Oral Biology, Faculty of Dentistry, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Bozena Kuzio
- Institute for Biodiagnostics, National Research Council of Canada, 435 Ellice Avenue, Winnipeg, MB R3B 1Y6, Canada
- Department of Oral Biology, Faculty of Dentistry, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Valery V. Kupriyanov
- Institute for Biodiagnostics, National Research Council of Canada, 435 Ellice Avenue, Winnipeg, MB R3B 1Y6, Canada
- Department of Oral Biology, Faculty of Dentistry, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada
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Karger AB, Park S, Reyes S, Bienengraeber M, Dyer RB, Terzic A, Alekseev AE. Role for SUR2A ED domain in allosteric coupling within the K(ATP) channel complex. ACTA ACUST UNITED AC 2008; 131:185-96. [PMID: 18299394 PMCID: PMC2248718 DOI: 10.1085/jgp.200709852] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Allosteric regulation of heteromultimeric ATP-sensitive potassium (KATP) channels is unique among protein systems as it implies transmission of ligand-induced structural adaptation at the regulatory SUR subunit, a member of ATP-binding cassette ABCC family, to the distinct pore-forming K+ (Kir6.x) channel module. Cooperative interaction between nucleotide binding domains (NBDs) of SUR is a prerequisite for KATP channel gating, yet pathways of allosteric intersubunit communication remain uncertain. Here, we analyzed the role of the ED domain, a stretch of 15 negatively charged aspartate/glutamate amino acid residues (948–962) of the SUR2A isoform, in the regulation of cardiac KATP channels. Disruption of the ED domain impeded cooperative NBDs interaction and interrupted the regulation of KATP channel complexes by MgADP, potassium channel openers, and sulfonylurea drugs. Thus, the ED domain is a structural component of the allosteric pathway within the KATP channel complex integrating transduction of diverse nucleotide-dependent states in the regulatory SUR subunit to the open/closed states of the K+-conducting channel pore.
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Affiliation(s)
- Amy B Karger
- Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, MN 55905, USA
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Tricarico D, Mele A, Camerino GM, Laghezza A, Carbonara G, Fracchiolla G, Tortorella P, Loiodice F, Camerino DC. Molecular determinants for the activating/blocking actions of the 2H-1,4-benzoxazine derivatives, a class of potassium channel modulators targeting the skeletal muscle KATP channels. Mol Pharmacol 2008; 74:50-8. [PMID: 18403717 DOI: 10.1124/mol.108.046615] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The 2H-1,4-benzoxazine derivatives are modulators of the skeletal muscle ATP-sensitive-K(+) channels (K(ATP)), activating it in the presence of ATP but inhibiting it in the absence of nucleotide. To investigate the molecular determinants for the activating/blocking actions of these compounds, novel molecules with different alkyl or aryl-alkyl substitutes at position 2 of the 1,4-benzoxazine ring were prepared. The effects of the lengthening of the alkyl chain and of branched substitutes, as well as of the introduction of aliphatic/aromatic rings on the activity of the molecules, were investigated on the skeletal muscle K(ATP) channels of the rat, in excised-patch experiments, in the presence or absence of internal ATP (10(-4) M). In the presence of ATP, the 2-n-hexyl analog was the most potent activator (DE(50) = 1.08 x 10(-10) M), whereas the 2-phenylethyl was not effective. The rank order of efficacy of the openers was 2-n-hexyl > or =2-cyclohexylmethyl >2-isopropyl = 2-n-butyl > or = 2-phenyl > or = 2-benzyl = 2-isobutyl analogs. In the absence of ATP, the 2-phenyl analog was the most potent inhibitor (IC(50) = 2.5 x 10(-11) M); the rank order of efficacy of the blockers was 2-phenyl > or = 2-n-hexyl > 2-n-butyl > 2-cyclohexylmethyl, whereas the 2-phenylethyl, 2-benzyl, and 2-isobutyl 1,4-benzoxazine analogs were not effective; the 2-isopropyl analog activated the K(ATP) channel even in the absence of nucleotide. Therefore, distinct molecular determinants for the activating or blocking actions for these compounds can be found. For example, the replacement of the linear with the branched alkyl substitutes at the position 2 of the 1,4-benzoxazine nucleus determines the molecular switch from blockers to openers. These compounds were 100-fold more potent and effective as openers than other KCO against the muscle K(ATP) channels.
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Affiliation(s)
- Domenico Tricarico
- Department of Pharmacobiology, Faculty of Pharmacy, via Orabona no. 4, Bari, Italy
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Wuest M, Kaden S, Hakenberg OW, Wirth MP, Ravens U. Effect of rilmakalim on detrusor contraction in the presence and absence of urothelium. Naunyn Schmiedebergs Arch Pharmacol 2005; 372:203-12. [PMID: 16283254 DOI: 10.1007/s00210-005-0015-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2005] [Accepted: 09/15/2005] [Indexed: 01/25/2023]
Abstract
Openers of K(ATP) channels are known to inhibit KCl-, carbachol- and also electrically induced contractions in detrusor muscle strips from various species. Contractions of isolated strips of urinary bladder are usually of higher amplitude when the urothelium has been removed. This has been explained by the release of an urothelium-derived relaxing factor. In this study we examined whether intact urothelium may modulate the effect of the selective KATP channel opener rilmakalim. Contractile responses to 85 mM KCl and 10 microM carbachol were measured in detrusor strips from mouse, pig and man. In the presence of an intact urothelium, contractions were significantly reduced in strips from all three species investigated. In preparations with urothelium rilmakalim reduced KCl contractions with similar potency and efficacy [-logIC50 (M) 4.6 to 5.1; Effmax reduction to 14-30% of control]. However, in urothelium-denuded strips rilmakalim was more potent in pig (-logIC50 5.5) than in mouse and man (-logIC50 4.7 and 4.4, respectively). The order of potency for rilmakalim to suppress carbachol-induced contractions was pig (-logIC50 6.7)>man (5.8)>mouse (4.7); contractions were significantly more reduced in pig (Effmax reduction to 11+/-2%, n=10) and in mouse (21+/-2%, n=8) than in human detrusor (55+/-5%, n=5). The presence of urothelium did not affect the concentration-response curves for rilmakalim, with the exception of KCl-induced contractions in pig. Only the rilmakalim-induced relaxation of carbachol-mediated contractions in pig were prevented by the KATP channel blocker glibenclamide. We conclude that with this one exception, the responses to rilmakalim in detrusor contractions were not mediated by KATP channel opening.
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Affiliation(s)
- Melinda Wuest
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, TU Dresden, Fetscherstrasse 74, 01307, Dresden, Germany.
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Stephan D, Stauß E, Lange U, Felsch H, Löffler-Walz C, Hambrock A, Russ U, Quast U. The mutation Y1206S increases the affinity of the sulphonylurea receptor SUR2A for glibenclamide and enhances the effects of coexpression with Kir6.2. Br J Pharmacol 2005; 144:1078-88. [PMID: 15711591 PMCID: PMC1576091 DOI: 10.1038/sj.bjp.0706142] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
1. ATP-sensitive K(+) channels (K(ATP) channels) are tetradimeric complexes of inwardly rectifying K(+) channels (Kir6.x) and sulphonylurea receptors (SURs). The SURs SUR2A (cardiac) and SUR2B (smooth muscle) differ only in the last 42 amino acids. In SUR2B, the mutation Y1206S, located at intracellular loop 8, increases the affinity for glibenclamide (GBC) about 10-fold. Here, we examined whether the mutation Y1206S in SUR2A had effects similar to those in SUR2B.2. GBC bound to SUR2A with K(D)=20 nM; the mutation increased affinity approximately 5 x. 3. In cells, coexpression of SUR2A with Kir6.2 increased the affinity for GBC approximately 3 x; with the mutant, the increase was 9 x. 4. The mutation did not affect the affinity of SUR2A for openers; coexpression with Kir6.2 reduced opener affinity of wild-type and mutant SUR2A by about 2 x. 5. The negative allosteric interaction between the opener, P1075, and GBC at wild-type and mutant SUR2A was markedly affected by the presence of MgATP and by coexpression with Kir6.2. 6. In inside-out patches, GBC inhibited the wild-type Kir6.2/SUR2A and 2B channels with IC(50) values of 27 nM; the mutation shifted the IC(50) values to approximately 1 nM. 7. The data show that the mutation Y1206S increased the affinity of SUR2A for GBC and modulated the effects of coexpression. Overall, the changes were similar to those observed with SUR2B(Y1206S), suggesting that the differences in the last 42 carboxy-terminal amino acids of SUR2A and 2B are of limited influence on the binding of GBC and P1075 to the SUR2 isoforms.
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Affiliation(s)
- Damian Stephan
- Department of Pharmacology and Toxicology, Medical Faculty, Pharmakologisches Institut/Abt. Molekularpharmakologie, University of Tübingen, Wilhelmstr. 56, Tübingen, D-72074 Germany
| | - Eva Stauß
- Department of Pharmacology and Toxicology, Medical Faculty, Pharmakologisches Institut/Abt. Molekularpharmakologie, University of Tübingen, Wilhelmstr. 56, Tübingen, D-72074 Germany
| | - Ulf Lange
- Department of Pharmacology and Toxicology, Medical Faculty, Pharmakologisches Institut/Abt. Molekularpharmakologie, University of Tübingen, Wilhelmstr. 56, Tübingen, D-72074 Germany
| | - Holger Felsch
- Department of Pharmacology and Toxicology, Medical Faculty, Pharmakologisches Institut/Abt. Molekularpharmakologie, University of Tübingen, Wilhelmstr. 56, Tübingen, D-72074 Germany
| | - Cornelia Löffler-Walz
- Department of Pharmacology and Toxicology, Medical Faculty, Pharmakologisches Institut/Abt. Molekularpharmakologie, University of Tübingen, Wilhelmstr. 56, Tübingen, D-72074 Germany
| | - Annette Hambrock
- Department of Pharmacology and Toxicology, Medical Faculty, Pharmakologisches Institut/Abt. Molekularpharmakologie, University of Tübingen, Wilhelmstr. 56, Tübingen, D-72074 Germany
| | - Ulrich Russ
- Department of Pharmacology and Toxicology, Medical Faculty, Pharmakologisches Institut/Abt. Molekularpharmakologie, University of Tübingen, Wilhelmstr. 56, Tübingen, D-72074 Germany
| | - Ulrich Quast
- Department of Pharmacology and Toxicology, Medical Faculty, Pharmakologisches Institut/Abt. Molekularpharmakologie, University of Tübingen, Wilhelmstr. 56, Tübingen, D-72074 Germany
- Author for correspondence:
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Bryan J, Vila-Carriles WH, Zhao G, Babenko AP, Aguilar-Bryan L. Toward linking structure with function in ATP-sensitive K+ channels. Diabetes 2004; 53 Suppl 3:S104-12. [PMID: 15561897 DOI: 10.2337/diabetes.53.suppl_3.s104] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Advances in understanding the overall structural features of inward rectifiers and ATP-binding cassette (ABC) transporters are providing novel insight into the architecture of ATP-sensitive K+ channels (KATP channels) (KIR6.0/SUR)4. The structure of the K(IR) pore has been modeled on bacterial K+ channels, while the lipid-A exporter, MsbA, provides a template for the MDR-like core of sulfonylurea receptor (SUR)-1. TMD0, an NH2-terminal bundle of five alpha-helices found in SURs, binds to and activates KIR6.0. The adjacent cytoplasmic L0 linker serves a dual function, acting as a tether to link the MDR-like core to the KIR6.2/TMD0 complex and exerting bidirectional control over channel gating via interactions with the NH2-terminus of the KIR. Homology modeling of the SUR1 core offers the possibility of defining the glibenclamide/sulfonylurea binding pocket. Consistent with 30-year-old studies on the pharmacology of hypoglycemic agents, the pocket is bipartite. Elements of the COOH-terminal half of the core recognize a hydrophobic group in glibenclamide, adjacent to the sulfonylurea moiety, to provide selectivity for SUR1, while the benzamido group appears to be in proximity to L0 and the KIR NH2-terminus.
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Affiliation(s)
- Joseph Bryan
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
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Padma-Nathan H, Christ G, Adaikan G, Becher E, Brock G, Carrier S, Carson C, Corbin J, Francis S, DeBusk R, Eardley I, Hedlund H, Hutter A, Jackson G, Kloner R, Lin CS, Lin S, McVary K, McCullough A, Nehra A, Porst H, Schulman C, Seftel A, Sharlip I, Stief C, Teloken C. Pharmacotherapy for Erectile Dysfunction. J Sex Med 2004; 1:128-40. [PMID: 16422967 DOI: 10.1111/j.1743-6109.2004.04021.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
INTRODUCTION Advances in understanding of the biochemistry and physiology of penile erection have led to breakthroughs in pharmacotherapy of erectile dysfunction. AIM To provide recommendations/guidelines concerning state-of-the-art knowledge for the putative molecular and cellular mechanisms of action of centrally and peripherally acting drugs currently utilized in pharmacotherapy of erectile dysfunction. METHODS An international consultation in collaboration with the major urology and sexual medicine associations assembled over 200 multidisciplinary experts from 60 countries into 17 committees. Committee members established specific objectives and scopes for various male and female sexual medicine topics. The recommendations concerning state-of-the-art knowledge in the respective sexual medicine topic represent the opinion of experts from five continents developed in a process over a two-year period. Concerning the Pharmacotherapy for Erectile Dysfunction Committee there were 25 experts from 10 countries. MAIN OUTCOME MEASURE Expert opinion was based on grading of evidence-based medical literature, widespread internal committee discussion, public presentation and debate. RESULTS Selective and potent oral PDE5 inhibitors have significantly more affinity than cGMP and form broader molecular interactions with multiple amino acids, thereby blocking access to cGMP in the catalytic sites of the PDE5 enzyme. PDE5 inhibitors, which vary as to biochemical potency, selectivity and pharmacokinetics, lead to cGMP elevation and relaxation facilitation of penile corpus cavernosum smooth muscle cells following sexual stimulation. Various centrally acting drugs influence sexual behaviour. In particular, the dopaminergic substance apomorphine is a central enhancer that acts in the paraventricular nucleus of the hypothalamus as a dopamine (D2) receptor agonist, induces and increases penile erection responses via disinhibition, following sexual stimulation. CONCLUSIONS There is a need for more research in the pharmacotherapeutic development of central and peripheral agents for safe and effective erectile dysfunction treatment.
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Felsch H, Lange U, Hambrock A, Löffler-Walz C, Russ U, Carroll WA, Gopalakrishnan M, Quast U. Interaction of a novel dihydropyridine K+ channel opener, A-312110, with recombinant sulphonylurea receptors and KATP channels: comparison with the cyanoguanidine P1075. Br J Pharmacol 2004; 141:1098-105. [PMID: 15023854 PMCID: PMC1574886 DOI: 10.1038/sj.bjp.0705718] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
1. ATP-sensitive K(+) channels (K(ATP) channels) are composed of pore-forming subunits (Kir6.x) and of regulatory subunits, the sulphonylurea receptors (SURx). Synthetic openers of K(ATP) channels form a chemically heterogeneous class of compounds that are of interest in several therapeutic areas. We have investigated the interaction of a novel dihydropyridine opener, A-312110 ((9R)-9-(4-fluoro-3-iodophenyl)-2,3,5,9-tetrahydro-4H-pyrano[3,4-b]thieno [2,3-e]pyridin-8(7H)-one-1,1-dioxide), with SURs and Kir6/SUR channels in comparison to the cyanoguanidine opener P1075. 2. In the presence of 1 mM MgATP, A-312110 bound to SUR2A (the SUR in cardiac and skeletal muscle) and to SUR2B (smooth muscle) with K(i) values of 14 and 18 nM; the corresponding values for P1075 were 16 and 9 nM, respectively. Decreasing the MgATP concentration reduced the affinity of A312110 binding to SUR2A significantly more than that to SUR2B; for P1075, the converse was true. At SUR1 (pancreatic beta-cell), both openers showed little binding up to 100 microM. 3. In the presence of MgATP, both openers inhibited [(3)H]glibenclamide binding to the SUR2 subtypes in a biphasic manner. In the absence of MgATP, the high-affinity component of the inhibition curves was absent. 4. In inside-out patches, the two openers activated the Kir6.2/SUR2A and Kir6.2/SUR2B channels with similar potency (approximately 50 nm). Both were almost 2 x more efficacious in opening the Kir6.2/SUR2B than the Kir6.2/SUR2A channel. 5. The results show that the novel dihydropyridine A-312110 is a potent K(ATP) channel opener with binding and channel-opening properties similar to those of P1075.
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MESH Headings
- ATP-Binding Cassette Transporters/drug effects
- ATP-Binding Cassette Transporters/genetics
- Adenosine Triphosphate/chemistry
- Adenosine Triphosphate/metabolism
- Cell Line
- Dihydropyridines/chemistry
- Dihydropyridines/pharmacology
- Drug Interactions/physiology
- Guanidines/chemistry
- Guanidines/pharmacology
- Humans
- Ion Channel Gating
- Kidney/cytology
- Kidney/embryology
- Magnesium/chemistry
- Magnesium/metabolism
- Membrane Proteins/chemistry
- Membrane Proteins/drug effects
- Membrane Proteins/genetics
- Muscle Fibers, Skeletal/cytology
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Myocytes, Cardiac/cytology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Patch-Clamp Techniques/methods
- Potassium Channels/drug effects
- Potassium Channels/genetics
- Potassium Channels/physiology
- Potassium Channels, Inwardly Rectifying/drug effects
- Potassium Channels, Inwardly Rectifying/genetics
- Pyridines/chemistry
- Pyridines/pharmacology
- Receptors, Drug/drug effects
- Receptors, Drug/genetics
- Recombinant Proteins/drug effects
- Recombinant Proteins/genetics
- Sulfonylurea Receptors
- Thiophenes/chemistry
- Thiophenes/pharmacology
- Tritium
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Affiliation(s)
- Holger Felsch
- Department of Pharmacology and Toxicology, Medical Faculty, University of Tübingen, Wilhelmstr. 56, D-72074 Tübingen, Germany
| | - Ulf Lange
- Department of Pharmacology and Toxicology, Medical Faculty, University of Tübingen, Wilhelmstr. 56, D-72074 Tübingen, Germany
| | - Annette Hambrock
- Department of Pharmacology and Toxicology, Medical Faculty, University of Tübingen, Wilhelmstr. 56, D-72074 Tübingen, Germany
| | - Cornelia Löffler-Walz
- Department of Pharmacology and Toxicology, Medical Faculty, University of Tübingen, Wilhelmstr. 56, D-72074 Tübingen, Germany
| | - Ulrich Russ
- Department of Pharmacology and Toxicology, Medical Faculty, University of Tübingen, Wilhelmstr. 56, D-72074 Tübingen, Germany
| | | | | | - Ulrich Quast
- Department of Pharmacology and Toxicology, Medical Faculty, University of Tübingen, Wilhelmstr. 56, D-72074 Tübingen, Germany
- Author for correspondence:
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