Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 8.253
Filtrar
1.
Life Sci ; 245: 117357, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31991180

RESUMO

AIMS: Schisandra is a good choice in Traditional Chinese Medicine for the therapy of cardiovascular diseases, but whether it contains a or some specific component (s) responsible these effects are still unclear. In the present study, we explored whether Schisantherin A (SCA) causes vasorelaxation in isolated rat thoracic aorta. MAIN METHODS: We selected SCA, one of the main monomers of lignans from Schisandra, to examine its vasorelaxant effect on the isolated rat thoracic aorta and also exploited several tool inhibitors to probe its underlying mechanisms. KEY FINDINGS: SCA produced relaxation concentration-dependently on the endothelium-intact (43.56 ± 2.17%) and endothelium-denuded thoracic aorta strips (18.76 ± 3.95%) pre-contracted by phenylephrine (PE). However, after treated with indomethacin or L-NAME, SCA showed only partial vasorelaxant effects. Whereas, this vasorelaxation by SCA was not changed with specific K+-channel inhibitors, i.e. barium chloride (BaCl2), 4-aminopyridine (4-AP), tetraethylamine (TEA), and glibenclamide. SCA had no effect on the aorta strips pre-contracted by PE in neither Ca2+-free nor CaCl2 conditions. But, in the Ca2+ free and high K+ environment, SCA partly abolished the vasocontraction induced by CaCl2. SIGNIFICANCE: It was the first report to demonstrate that SCA had endothelium-dependent and -independent vasorelaxant effects on the isolated rat thoracic aorta, and the underlying mechanisms might be involved into its promoting the production of nitric oxide (NO) and prostacyclin (PGI2), and inhibiting the voltage-dependent calcium channels (VDCCs) opening. This study may partially explain the use of Schisandra in cardiovascular diseases and facilitate further drug development as well.


Assuntos
Aorta Torácica/efeitos dos fármacos , Ciclo-Octanos/farmacologia , Dioxóis/farmacologia , Endotélio Vascular/efeitos dos fármacos , Lignanas/farmacologia , Vasodilatação/efeitos dos fármacos , Vasodilatadores/farmacologia , Animais , Aorta Torácica/fisiologia , Western Blotting , Cálcio/metabolismo , Relação Dose-Resposta a Droga , Endotélio Vascular/fisiologia , Masculino , Bloqueadores dos Canais de Potássio/farmacologia , Ratos , Ratos Sprague-Dawley , Reação em Cadeia da Polimerase Via Transcriptase Reversa
2.
Toxicol Lett ; 319: 40-48, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31706004

RESUMO

Two synthetic tryptamines, namely [3-[2-(diethylamino)ethyl]-1H-indol-4-yl] acetate (4-AcO-DET) and 3-[2-[ethyl(methyl)amino]ethyl]-1H-indol-4-ol (4-HO-MET), are abused by individuals seeking recreational hallucinogens. These new psychoactive substances (NPSs) can cause serious health problems because their adverse effects are mostly unknown. In the present study, we evaluated the cardiotoxicity of 4-AcO-DET and 4-HO-MET using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, electrocardiography (ECG), and the human ether-a-go-go-related gene (hERG) assay. In addition, we analyzed the expression level of p21 (CDC42/RAC)-activated kinase 1 (PAK1), which is known to play various roles in the cardiovascular system. In the MTT assay, 4-AcO-DET- and 4-HO-MET-treated H9c2 cells proliferated in a concentration-dependent manner. Moreover, both substances increased QT intervals (as determined using ECG) in Sprague-Dawley rats and inhibited potassium channels (as verified by the hERG assay) in Chinese hamster ovary cells. However, there was no change in PAK1 expression. Collectively, the results indicated that 4-AcO-DET and 4-HO-MET might cause adverse effects on the cardiovascular system. Further studies are required to confirm the relationship between PAK1 expression and cardiotoxicity. The findings of the present study would provide science-based evidence for scheduling the two NPSs.


Assuntos
Cardiotoxinas/toxicidade , Alucinógenos/toxicidade , Triptaminas/toxicidade , Animais , Células CHO , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Cricetulus , Canal de Potássio ERG1/metabolismo , Eletrocardiografia , Masculino , Miócitos Cardíacos/efeitos dos fármacos , Bloqueadores dos Canais de Potássio/toxicidade , Ratos , Ratos Sprague-Dawley , Quinases Ativadas por p21/biossíntese , Quinases Ativadas por p21/genética
3.
Life Sci ; 240: 117068, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31751583

RESUMO

AIMS: Bradycardia contributes to tachy-brady arrhythmias or sinus arrest during heart failure (HF). Sinoatrial node (SAN) adenosine A1 receptors (ADO A1Rs) are upregulated in HF, and adenosine is known to exert negative chronotropic effects on the SAN. Here, we investigated the role of A1R signaling at physiologically relevant ADO concentrations on HF SAN pacemaker cells. MAIN METHODS: Dogs with tachypacing-induced chronic HF and normal controls (CTL) were studied. SAN tissue was collected for A1R and GIRK mRNA quantification. SAN cells were isolated for perforated patch clamp recordings and firing rate (bpm), slope of slow diastolic depolarization (SDD), and maximum diastolic potential (MDP) were measured. Action potentials (APs) and currents were recorded before and after addition of 1 and 10 µM ADO. To assess contributions of A1R and G protein-coupled Inward Rectifier Potassium Current (GIRK) to ADO effects, APs were measured after the addition of DPCPX (selective A1R antagonist) or TPQ (selective GIRK blocker). KEY FINDINGS: A1R and GIRK mRNA expression were significantly increased in HF. In addition, ADO induced greater rate slowing and membrane hyperpolarization in HF vs CTL (p < 0.05). DPCPX prevented ADO-induced rate slowing in CTL and HF cells. The ADO-induced inward rectifying current, IKado, was observed significantly more frequently in HF than in CTL. TPQ prevented ADO-induced rate slowing in HF. SIGNIFICANCE: An increase in A1R and GIRK expression enhances IKAdo, causing hyperpolarization, and subsequent negative chronotropic effects in canine chronic HF at relevant [ADO]. GIRK blockade may be a useful strategy to mitigate bradycardia in HF.


Assuntos
Agonistas do Receptor A1 de Adenosina/farmacologia , Adenosina/farmacologia , Canais de Potássio Corretores do Fluxo de Internalização Acoplados a Proteínas G/agonistas , Insuficiência Cardíaca/fisiopatologia , Frequência Cardíaca/efeitos dos fármacos , Receptor A1 de Adenosina/metabolismo , Nó Sinoatrial/citologia , Nó Sinoatrial/efeitos dos fármacos , Potenciais de Ação/efeitos dos fármacos , Antagonistas do Receptor A1 de Adenosina/farmacologia , Animais , Venenos de Abelha/farmacologia , Relógios Biológicos , Doença Crônica , Cães , Feminino , Canais de Potássio Corretores do Fluxo de Internalização Acoplados a Proteínas G/antagonistas & inibidores , Canais de Potássio Corretores do Fluxo de Internalização Acoplados a Proteínas G/efeitos dos fármacos , Técnicas In Vitro , Masculino , Técnicas de Patch-Clamp , Bloqueadores dos Canais de Potássio/farmacologia , Receptor A1 de Adenosina/efeitos dos fármacos , Xantinas/farmacologia
4.
Science ; 366(6472): 1486-1492, 2019 12 20.
Artigo em Inglês | MEDLINE | ID: mdl-31857479

RESUMO

Disruptions in the ubiquitin protein ligase E3A (UBE3A) gene cause Angelman syndrome (AS). Whereas AS model mice have associated synaptic dysfunction and altered plasticity with abnormal behavior, whether similar or other mechanisms contribute to network hyperactivity and epilepsy susceptibility in AS patients remains unclear. Using human neurons and brain organoids, we demonstrate that UBE3A suppresses neuronal hyperexcitability via ubiquitin-mediated degradation of calcium- and voltage-dependent big potassium (BK) channels. We provide evidence that augmented BK channel activity manifests as increased intrinsic excitability in individual neurons and subsequent network synchronization. BK antagonists normalized neuronal excitability in both human and mouse neurons and ameliorated seizure susceptibility in an AS mouse model. Our findings suggest that BK channelopathy underlies epilepsy in AS and support the use of human cells to model human developmental diseases.


Assuntos
Síndrome de Angelman/metabolismo , Canais de Cálcio Tipo N/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Síndrome de Angelman/fisiopatologia , Animais , Epilepsia/metabolismo , Humanos , Camundongos , Modelos Neurológicos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Organoides , Bloqueadores dos Canais de Potássio/farmacologia , Bloqueadores dos Canais de Potássio/uso terapêutico , Convulsões/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitinação
5.
Fitoterapia ; 139: 104394, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31669719

RESUMO

Naturally occurring monoterpenes are known for their various pharmacological activities including anti-inflammation. KV1.3 ion channel is a voltage-gated potassium channel and has been validated as a drug target for autoimmune and chronic inflammatory diseases like psoriasis. Here we experimentally test the direct interaction between monoterpenes and KV1.3 ion channel. Our electrophysiological analysis determined that monoterpenes (geraniol, nerol, ß-citronellol, citral and linalool) have inhibitory effects on KV1.3 ion channel. Representatively, geraniol reversibly blocked KV1.3 currents in a voltage-dependent manner with an IC50 of 490.50 ±â€¯1.04 µM at +40 mV in HEK293T cells. At the effective concentrations, geraniol also inhibited cytokine secretion of activated human T cells, including IL-2, TNF-α and IFN-γ. In an imiquimod-induced psoriasis-like animal model, geraniol administration significantly reduced psoriasis area and severity index scores, ameliorated the deteriorating histopathology and decreased the degree of splenomegaly. Together, our findings not only suggest that monoterpenes may serve as lead molecules for the development of KV1.3 inhibitors, but also indicate that geraniol could be considered as a promising therapeutic candidate to treat autoimmune diseases.


Assuntos
/farmacologia , Anti-Inflamatórios/farmacologia , Canal de Potássio Kv1.3/antagonistas & inibidores , Bloqueadores dos Canais de Potássio/farmacologia , Animais , Citocinas/metabolismo , Modelos Animais de Doenças , Células HEK293 , Humanos , Masculino , Camundongos Endogâmicos BALB C , Psoríase/tratamento farmacológico , Linfócitos T/efeitos dos fármacos , Linfócitos T/metabolismo
6.
J Physiol Pharmacol ; 70(3)2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31566191

RESUMO

We hypothesized that the repolarization phase of action potentials (APs) in mammals with large body mass and high cardiac output could not be reliably controlled by only one of the delayed rectifier potassium IK current components. To test this hypothesis experimentally, we performed a comparative study of the response of AP phases to the rapid IKr channels blocker E-4031 and slow IKs blocker chromanol 293B in APs spontaneously generated in strips of sinoauricular (SA) tissue from mouse, guinea pig, and pig hearts. Application of a slow channels blocker chromanol 293B caused a decrease of Aps generation frequency in SA area strips from mouse, guinea-pig and pig by 5.3, 16, and 18% compared to the control. Treatment with the IKr blocker E-4031 caused a significant reduction of APs generation frequency in the mouse, guinea pig, and pig SA strips by 24, 26, and 36%, respectively, compared to the control values. These results suggest that the rapid IKr current is the key component responsible for AP generation in sinoauricular node cells of the pig heart.


Assuntos
Potenciais de Ação/efeitos dos fármacos , Canais de Potássio/metabolismo , Potássio/metabolismo , Nó Sinoatrial/fisiologia , Animais , Cromanos/farmacologia , Cobaias , Masculino , Camundongos , Bloqueadores dos Canais de Potássio/farmacologia , Nó Sinoatrial/metabolismo , Sulfonamidas/farmacologia , Suínos
7.
Prog Chem Org Nat Prod ; 110: 177-238, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31621014

RESUMO

Interference with the hERG potassium ion channel may cause cardiac arrhythmia and can even lead to death. Over the last few decades, several drugs, already on the market, and many more investigational drugs in various development stages, have had to be discontinued because of their hERG-associated toxicity. To recognize potential hERG activity in the early stages of drug development, a wide array of computational tools, based on different principles, such as 3D QSAR, 2D and 3D similarity, and machine learning, have been developed and are reviewed in this chapter. The various available prediction tools Similarity Ensemble Approach, SuperPred, SwissTargetPrediction, HitPick, admetSAR, PASSonline, Pred-hERG, and VirtualToxLab™ were used to screen a dataset of known hERG synthetic and natural product actives and inactives to quantify and compare their predictive power. This contribution will allow the reader to evaluate the suitability of these computational methods for their own related projects. There is an unmet need for natural product-specific prediction tools in this field.


Assuntos
Produtos Biológicos/farmacologia , Biologia Computacional , Canais de Potássio Éter-A-Go-Go/antagonistas & inibidores , Bloqueadores dos Canais de Potássio/farmacologia , Química Farmacêutica , Humanos , Aprendizado de Máquina , Modelos Moleculares , Relação Quantitativa Estrutura-Atividade
8.
Expert Rev Clin Pharmacol ; 12(11): 1013-1018, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31639317

RESUMO

Introduction: Lambert-Eaton myasthenic syndrome is an autoimmune disease of the neuromuscular junction characterized by a presynaptic defect of neuromuscular transmission resulting in muscle weakness and fatigability. Diagnostic features are specific neurophysiological alterations and autoantibody detection. The present review is focused on the use of Amifampridine Phosphate to treat LEMS patients.Areas covered: Medline search from 1990 to 2019 was examined using the free subject terms: Lambert-Eaton myasthenic syndrome, LEMS, Amifampridine, 3,4-diaminopyridine, which were then combined with Treatment, Therapy, Clinical Trial, Controlled Clinical Trial, Randomized Clinical Trial and Cochrane Review. The author has done a supervised analysis of the retrieved articles and focused on those subjectively evaluated as most relevant.Expert commentary: Data from randomized clinical trials and case series have demonstrated that Lambert-Eaton myasthenic syndrome symptoms were successfully treated by Amifampridine Phosphate. Hence, the drug represents a substantial step forward in the symptomatic treatment of the disease due to its efficacy, safety and reliable GMP formulation. As Amifampridine Phosphate works by enhancing the release of acetylcholine at the neuromuscular junction by blocking K+ efflux at the pre-synaptic membrane, it is also conceivable to use it for other diseases of the neuromuscular junction in which such an effect is searched for.


Assuntos
Amifampridina/administração & dosagem , Síndrome Miastênica de Lambert-Eaton/tratamento farmacológico , Fármacos Neuromusculares/administração & dosagem , Amifampridina/efeitos adversos , Amifampridina/farmacologia , Humanos , Síndrome Miastênica de Lambert-Eaton/fisiopatologia , Fármacos Neuromusculares/efeitos adversos , Fármacos Neuromusculares/farmacologia , Bloqueadores dos Canais de Potássio/administração & dosagem , Bloqueadores dos Canais de Potássio/efeitos adversos , Bloqueadores dos Canais de Potássio/farmacologia , Ensaios Clínicos Controlados Aleatórios como Assunto , Comprimidos
9.
Undersea Hyperb Med ; 46(4): 483-494, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31509904

RESUMO

The aim of this study was to establish the effect of combined therapy with hyperbaric oxygen (HBO2) therapy and verapamil, amlodipine or nicorandil on functional recovery and oxidative stress markers after ischemia in the isolated rat heart. The study included 48 rats (Wistar albino, male gender, eight weeks old, body weight 200±50g). All animals were exposed to HBO2 treatment over 14 days. Isolated heart rats were perfused by the Langendorff retrograde method at a constant coronary pressure of 70 cm H2O. After stabilization period the hearts were divided into the following groups: HBO2 group (animals exposed to only HBO2 preconditioning); HBO2 + verapamil; HBO2 + amlodipine; andHBO2 + nicorandil (animals pretreated with HBO2 and appropriate pharmacological agent). Afterward, the hearts in all groups were subjected to 20-minute global ischemia and 30-minute reperfusion. Parameters of heart function were registered, including maximum and minimum rate of pressure development, systolic and diastolic left ventricular pressure, heart rate and coronary flow. Levels of pro-oxidants such as index of lipid peroxidation, measured as thiobarbituric acid-reactive substances, nitrites, levels of superoxide anion radicals and hydrogen peroxide were determined in coronary venous effluent. Changes in cardiac tissue were evaluated by hematoxylin and eosin staining. Obtained results clearly indicate that blockage of calcium channel or the activation of adenosine triphosphate-sensitive potassium (KATP) in combination with HBO2 prevented ischemia/reperfusion-induced cardiac deleterious effects, thus contributing to improvement of functional recovery of the heart. However, future studies are certainly necessary for better understanding the mechanisms through which combination of these two maneuvers of preconditioning triggers cardioprotection.


Assuntos
Bloqueadores dos Canais de Cálcio/uso terapêutico , Oxigenação Hiperbárica , Precondicionamento Isquêmico Miocárdico/métodos , Isquemia Miocárdica/terapia , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Bloqueadores dos Canais de Potássio/uso terapêutico , Anlodipino/uso terapêutico , Animais , Pressão Sanguínea/efeitos dos fármacos , Terapia Combinada/métodos , Circulação Coronária , Coração , Frequência Cardíaca/efeitos dos fármacos , Precondicionamento Isquêmico Miocárdico/efeitos adversos , Peroxidação de Lipídeos , Masculino , Miocárdio/patologia , Nicorandil/uso terapêutico , Estresse Oxidativo , Ratos , Ratos Wistar , Recuperação de Função Fisiológica , Verapamil/uso terapêutico
10.
PLoS Pathog ; 15(9): e1008041, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31553770

RESUMO

Filariae are parasitic nematodes that are transmitted to their definitive host as third-stage larvae by arthropod vectors like mosquitoes. Filariae cause diseases including: lymphatic filariasis with distressing and disturbing symptoms like elephantiasis; and river blindness. Filarial diseases affect millions of people in 73 countries throughout the topics and sub-tropics. The drugs available for mass drug administration, (ivermectin, albendazole and diethylcarbamazine), are ineffective against adult filariae (macrofilariae) at the registered dosing regimen; this generates a real and urgent need to identify effective macrofilaricides. Emodepside, a veterinary anthelmintic registered for treatment of nematode infections in cats and dogs, is reported to have macrofilaricidal effects. Here, we explore the mode of action of emodepside using adult Brugia malayi, one of the species that causes lymphatic filariasis. Whole-parasite motility measurement with Worminator and patch-clamp of single muscle cells show that emodepside potently inhibits motility by activating voltage-gated potassium channels and that the male is more sensitive than the female. RNAi knock down suggests that emodepside targets SLO-1 K channels. We expressed slo-1 isoforms, with alternatively spliced exons at the RCK1 (Regulator of Conductance of Potassium) domain, heterologously in Xenopus laevis oocytes. We discovered that the slo-1f isoform, found in muscles of males, is more sensitive to emodepside than the slo-1a isoform found in muscles of females; and selective RNAi of the slo-1a isoform in female worms increased emodepside potency. In Onchocerca volvulus, that causes river blindness, we found two isoforms in adult females with homology to Bma-SLO-1A and Bma-SLO-1F at the RCK1 domain. In silico modeling identified an emodepside binding pocket in the same RCK1 region of different species of filaria that is affected by these splice variations. Our observations show that emodepside has potent macrofilaricidal effects and alternative splicing in the RCK1 binding pocket affects potency. Therefore, the evaluation of potential sex-dependent effects of an anthelmintic compound is of importance to prevent any under-dosing of one or the other gender of nematodes once given to patients.


Assuntos
Brugia Malayi/efeitos dos fármacos , Brugia Malayi/fisiologia , Depsipeptídeos/farmacologia , Filaricidas/farmacologia , Canais de Potássio Ativados por Cálcio de Condutância Alta/metabolismo , Processamento Alternativo , Sequência de Aminoácidos , Animais , Sítios de Ligação/genética , Brugia Malayi/genética , Feminino , Filariose/tratamento farmacológico , Filariose/parasitologia , Técnicas de Silenciamento de Genes , Humanos , Canais de Potássio Ativados por Cálcio de Condutância Alta/química , Canais de Potássio Ativados por Cálcio de Condutância Alta/genética , Masculino , Modelos Moleculares , Movimento/efeitos dos fármacos , Movimento/fisiologia , Músculos/efeitos dos fármacos , Músculos/fisiologia , Peptídeos/farmacologia , Bloqueadores dos Canais de Potássio/farmacologia , Homologia de Sequência de Aminoácidos , Fatores Sexuais
11.
J Ethnopharmacol ; 245: 112156, 2019 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-31415847

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Uapaca togoensis is a medicinal plant used traditionally in Africa for the treatment of rheumatism, epilepsy, cough, pneumonia, vomitting and fever. Previously, the analgesic activity of its methanol stem bark extract has been scientifically demonstrated. However, the mechanism responsible for this activity remains to be investigated. AIM OF THE STUDY: To elucidate the possible mechanism(s) through which the methanol stem bark extract of Uapaca togoensis (MEUT) exhibits analgesic activity in mice. MATERIALS AND METHODS: Analgesic activity of MEUT was evaluated using acetic acid-induced abdominal writhing test in mice at doses of 250, 500 and 1000 mg/kg orally. For the mechanistic studies, mice were pre-treated with Naloxone (2 mg/kg), Atropine (1 mg/kg), Yohimbine (1 mg/kg), Glibenclamide (10 mg/kg), Prazosin (1 mg/kg) and Yohimbine (1 mg/kg) 15 min prior to MEUT (1000 mg/kg) administration, then assessed using AAWT 1 h later. Data was analysed using One way Anova followed by Bonferroni post hoc test. RESULTS: The extract (at the doses of 250, 500 and 1000 mg/kg) and morphine (10 mg/kg) significantly (p < 0.05) decreased the number of abdominal writhes. Naloxone (opioid receptor antagonist), Atropine (muscarinic receptor antagonist) and Glibenclamide (ATP-sensitive K+ channel blocker) significantly (p < 0.05) reversed the analgesic effect of MEUT. On the other hand, Prazosin and Yohimbine (α1 and α2 receptor antagonists respectively) had no effect on the analgesic action of MEUT. CONCLUSION: The results obtained from this study suggests the possible involvement of opioidergic, cholinergic and sensitive potassium ATP channel pathways in the analgesic activity of the methanol stem bark extract of Uapaca togoensis.


Assuntos
Analgésicos/uso terapêutico , Coffea , Dor/tratamento farmacológico , Extratos Vegetais/uso terapêutico , Ácido Acético , Analgésicos/toxicidade , Animais , Atropina/farmacologia , Feminino , Glibureto/farmacologia , Dose Letal Mediana , Masculino , Metanol/química , Camundongos , Antagonistas Muscarínicos/farmacologia , Naloxona/farmacologia , Antagonistas de Entorpecentes/farmacologia , Dor/induzido quimicamente , Casca de Planta/química , Extratos Vegetais/toxicidade , Bloqueadores dos Canais de Potássio/farmacologia , Solventes/química
12.
Int J Mol Sci ; 20(16)2019 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-31426491

RESUMO

TASK-3 is a two-pore domain potassium (K2P) channel highly expressed in the hippocampus, cerebellum, and cortex. TASK-3 has been identified as an oncogenic potassium channel and it is overexpressed in different cancer types. For this reason, the development of new TASK-3 blockers could influence the pharmacological treatment of cancer and several neurological conditions. In the present work, we searched for novel TASK-3 blockers by using a virtual screening protocol that includes pharmacophore modeling, molecular docking, and free energy calculations. With this protocol, 19 potential TASK-3 blockers were identified. These molecules were tested in TASK-3 using patch clamp, and one blocker (DR16) was identified with an IC50 = 56.8 ± 3.9 µM. Using DR16 as a scaffold, we designed DR16.1, a novel TASK-3 inhibitor, with an IC50 = 14.2 ± 3.4 µM. Our finding takes on greater relevance considering that not many inhibitory TASK-3 modulators have been reported in the scientific literature until today. These two novel TASK-3 channel inhibitors (DR16 and DR16.1) are the first compounds found using a pharmacophore-based virtual screening and rational drug design protocol.


Assuntos
Bloqueadores dos Canais de Potássio/farmacologia , Canais de Potássio de Domínios Poros em Tandem/antagonistas & inibidores , Desenho de Drogas , Células HEK293 , Humanos , Simulação de Acoplamento Molecular , Bloqueadores dos Canais de Potássio/farmacocinética
13.
J Vet Med Sci ; 81(9): 1266-1272, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31292350

RESUMO

The aim of the present study was to clarify roles of ATP-dependent potassium channels (KATP channels) in motility of the striated muscle portion in the esophagus. An isolated segment of the rat esophagus was placed in an organ bath and mechanical responses were recorded using a force transducer. Electrical stimulation of the vagus nerve evoked contractile response of striated muscle in the esophageal segment. Application of glibenclamide, an antagonist of KATP channels, increased amplitude of vagally mediated twitch contractions of the rat esophagus. On the other hand, minoxidil, an agonist of KATP channels, decreased amplitude of twitch contractions. RT-PCR revealed the expression of subunits of KATP channels in esophageal tissue. In addition, immunopositivity for subunits of KATP channels was observed in the striated muscle cells of the esophageal muscle layer. These findings indicate that KATP channels contribute to motor regulation of striated muscle in the rat esophagus.


Assuntos
Esôfago/inervação , Contração Muscular/fisiologia , Músculo Estriado/fisiologia , Canais de Potássio/fisiologia , Trifosfato de Adenosina , Animais , Estimulação Elétrica , Esôfago/efeitos dos fármacos , Glibureto/farmacologia , Masculino , Minoxidil/farmacologia , Contração Muscular/efeitos dos fármacos , Músculo Estriado/efeitos dos fármacos , Bloqueadores dos Canais de Potássio/farmacologia , Canais de Potássio/efeitos dos fármacos , Ratos Sprague-Dawley , Nervo Vago/fisiologia
14.
Muscle Nerve ; 60(3): 292-298, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31269226

RESUMO

INTRODUCTION: There are no validated, practical, and quantitative measures of disease severity in Lambert-Eaton myasthenia (LEM). METHODS: Data from the Effectiveness of 3,4-Diaminopyridine in Lambert-Eaton Myasthenic Syndrome (DAPPER) trial were analyzed to assess triple timed up-and-go (3TUG) reproducibility and relationships between 3TUG times and other measures of LEM severity. RESULTS: The coverage probability technique showed ≥0.90 probability for an acceptable 3TUG difference of ≤0.2, indicating that it is reproducible in LEM patients. The correlation between 3TUG times and lower extremity function scores was significant in subjects who continued and in those who were withdrawn from 3,4-diaminopyridine free base. Worsening patient-reported Weakness Self-Assessment Scale and Investigator Assessment of Treatment Effect scores corresponded with prolongation of 3TUG times. DISCUSSION: The 3TUG is reproducible, demonstrates construct validity for assessment of lower extremity function in LEM patients, and correlates with changes in patient and physician assessments. These findings, along with prior reliability studies, indicate 3TUG is a valid measure of disease severity in LEM.


Assuntos
Síndrome Miastênica de Lambert-Eaton/fisiopatologia , Extremidade Inferior/fisiopatologia , Debilidade Muscular/fisiopatologia , Humanos , Programas de Rastreamento/métodos , Debilidade Muscular/tratamento farmacológico , Bloqueadores dos Canais de Potássio/uso terapêutico , Reprodutibilidade dos Testes , Índice de Gravidade de Doença
15.
J Neurol ; 266(Suppl 1): 93-100, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31270663

RESUMO

Vestibulo-ocular reflexes (VOR) are mediated by frequency-tuned pathways that separately transform the different dynamic and static aspects of head motion/position-related sensory signals into extraocular motor commands. Voltage-dependent potassium conductances such as those formed by Kv1.1 are important for the ability of VOR circuit elements to encode highly transient motion components. Here we describe the impact of the Kv1.1 channel blocker 4-aminopyridine (4-AP) on spontaneous and motion-evoked discharge of superior oblique motoneurons. Spike activity was recorded from the motor nerve in isolated preparations of Xenopus laevis tadpoles. Under static conditions, bath application of 1-10 µM 4-AP increased the spontaneous firing rate and provoked repetitive bursts of spikes. During motion stimulation 4-AP also augmented and delayed the peak firing rate suggesting that this drug affects the magnitude and timing of vestibular-evoked eye movements. The exclusive Kv1.1 expression in thick vestibular afferent fibers in larval Xenopus at this developmental stage suggests that the altered extraocular motor output in the presence of 4-AP mainly derives from a firing rate increase of irregular firing vestibular afferents that propagates along the VOR circuitry. Clinically and pharmacologically, the observed 4-AP-mediated increase of peripheral vestibular input under resting and dynamic conditions can contribute to the observed therapeutic effects of 4-AP in downbeat and upbeat nystagmus as well as episodic ataxia type 2, by an indirect increase of cerebellar Purkinje cell discharge.


Assuntos
4-Aminopiridina/administração & dosagem , Movimentos Oculares/efeitos dos fármacos , Bloqueadores dos Canais de Potássio/administração & dosagem , Reflexo Vestíbulo-Ocular/efeitos dos fármacos , Vestíbulo do Labirinto/efeitos dos fármacos , Animais , Movimentos Oculares/fisiologia , Feminino , Masculino , Reflexo Vestíbulo-Ocular/fisiologia , Vestíbulo do Labirinto/fisiologia , Xenopus laevis
16.
Pharm Res ; 36(9): 137, 2019 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-31332533

RESUMO

PURPOSE: Pitt Hopkins Syndrome (PTHS) is a rare genetic disorder caused by mutations of a specific gene, transcription factor 4 (TCF4), located on chromosome 18. PTHS results in individuals that have moderate to severe intellectual disability, with most exhibiting psychomotor delay. PTHS also exhibits features of autistic spectrum disorders, which are characterized by the impaired ability to communicate and socialize. PTHS is comorbid with a higher prevalence of epileptic seizures which can be present from birth or which commonly develop in childhood. Attenuated or absent TCF4 expression results in increased translation of peripheral ion channels Kv7.1 and Nav1.8 which triggers an increase in after-hyperpolarization and altered firing properties. METHODS: We now describe a high throughput screen (HTS) of 1280 approved drugs and machine learning models developed from this data. The ion channels were expressed in either CHO (KV7.1) or HEK293 (Nav1.8) cells and the HTS used either 86Rb+ efflux (KV7.1) or a FLIPR assay (Nav1.8). RESULTS: The HTS delivered 55 inhibitors of Kv7.1 (4.2% hit rate) and 93 inhibitors of Nav1.8 (7.2% hit rate) at a screening concentration of 10 µM. These datasets also enabled us to generate and validate Bayesian machine learning models for these ion channels. We also describe a structure activity relationship for several dihydropyridine compounds as inhibitors of Nav1.8. CONCLUSIONS: This work could lead to the potential repurposing of nicardipine or other dihydropyridine calcium channel antagonists as potential treatments for PTHS acting via Nav1.8, as there are currently no approved treatments for this rare disorder.


Assuntos
Di-Hidropiridinas/farmacologia , Reposicionamento de Medicamentos/métodos , Hiperventilação/tratamento farmacológico , Deficiência Intelectual/tratamento farmacológico , Canal de Potássio KCNQ1/antagonistas & inibidores , Canal de Sódio Disparado por Voltagem NAV1.8/metabolismo , Bloqueadores dos Canais de Potássio/farmacologia , Bloqueadores dos Canais de Sódio/farmacologia , Bloqueadores do Canal de Sódio Disparado por Voltagem/farmacologia , Animais , Teorema de Bayes , Células CHO , Cricetulus , Di-Hidropiridinas/química , Facies , Células HEK293 , Humanos , Canal de Potássio KCNQ1/metabolismo , Aprendizado de Máquina , Bloqueadores dos Canais de Potássio/química , Bibliotecas de Moléculas Pequenas/química , Bloqueadores dos Canais de Sódio/química , Relação Estrutura-Atividade , Bloqueadores do Canal de Sódio Disparado por Voltagem/química
17.
BMC Pharmacol Toxicol ; 20(1): 42, 2019 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-31315662

RESUMO

BACKGROUND: KCNH family of potassium channels is responsible for diverse physiological functions ranging from the regulation of neuronal excitability and cardiac contraction to the regulation of cancer progression. KCNH channels contain a Per-Arn-Sim (PAS) domain in their N-terminal and cyclic nucleotide-binding homology (CNBH) domain in their C-terminal regions. These intracellular domains shape the function of KCNH channels and are important targets for drug development. METHODS: Here we describe a surface plasmon resonance (SPR)-based screening method aimed in identifying small molecule binders of PAS and CNBH domains for three KCNH channel subfamilies: ether-à-go-go (EAG), EAG-related gene (ERG), and EAG-like K+ (ELK). The method involves purification of the PAS and CNBH domains, immobilization of the purified domains on the SPR senor chip and screening small molecules in a chemical library for binding to the immobilized domains using changes in the SPR response as a reporter of the binding. The advantages of this method include low quantity of purified PAS and CNBH domains necessary for the implementation of the screen, direct assessment of the small molecule binding to the PAS and CNBH domains and easiness of assessing KCNH subfamily specificity of the small molecule binders. RESULTS: Using the SPR-based method we screened the Spectrum Collection Library of 2560 compounds against the PAS and CNBH domains of the three KCNH channel subfamilies and identified a pool of small molecules that bind to the PAS or CNBH domains. To further evaluate the effectiveness of the screen we tested the functional effect of one of the identified mEAG PAS domain specific small molecule binders on currents recorded from EAG channels. Undecylenic acid inhibited currents recorded from EAG channels in a concentration-dependent manner with IC50 of ~ 1 µM. CONCLUSION: Our results show that the SPR-based method is well suited for identifying small molecule binders of KCNH channels and can facilitate drug discovery for other ion channels as well.


Assuntos
Canais de Potássio Éter-A-Go-Go/antagonistas & inibidores , Bloqueadores dos Canais de Potássio/farmacologia , Ácidos Undecilênicos/farmacologia , Animais , Descoberta de Drogas/métodos , Canais de Potássio Éter-A-Go-Go/fisiologia , Humanos , Camundongos , Oócitos/fisiologia , Domínios Proteicos , Bibliotecas de Moléculas Pequenas , Ressonância de Plasmônio de Superfície , Xenopus laevis
18.
Neurology ; 93(8): e733-e746, 2019 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-31331968

RESUMO

OBJECTIVE: To test a possible benefit of dalfampridine on information processing speed (IPS), a key function for cognitive impairment (CogIm) in multiple sclerosis (MS). METHODS: In this randomized, double-blind, placebo-controlled trial, we included patients with a score on the Symbol Digit Modalities Test (SDMT) under the 10th percentile of the reference value. Patients were randomized in a 2:1 ratio to receive dalfampridine 10 mg or placebo twice daily for 12 weeks. They underwent a comprehensive neuropsychological evaluation at screening (T0), at the end of treatment (T1), and after a 4-week follow-up (T2). The primary endpoint was improvement in SDMT. RESULTS: Out of 208 patients screened, 120 were randomized to receive either dalfampridine (n = 80) or placebo (n = 40). At T1, the dalfampridine group presented an increase of SDMT scores vs placebo group (mean change 9.9 [95% confidence interval (CI) 8.5-11.4] vs 5.2 [95% CI 2.8-7.6], p = 0.0018; d = 0.60 for raw score; and 0.8 [95% CI 0.6-1] vs 0.3 [95% CI 0.0-0.5], p = 0.0013; d = 0.61 for z scores; by linear mixed model with robust standard error). The improvement was not sustained at T2. A beneficial effect of dalfampridine was observed in the Paced Auditory Serial Addition Test and in cognitive fatigue. CONCLUSION: Dalfampridine could be considered as an effective treatment option for IPS impairment in MS. TRIAL REGISTRATION: 2013-002558-64 EU Clinical Trials Register. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that for patients with MS with low scores on the SDMT, dalfampridine improves IPS.


Assuntos
4-Aminopiridina/uso terapêutico , Transtornos Cognitivos/tratamento farmacológico , Esclerose Múltipla/tratamento farmacológico , Adolescente , Adulto , Idoso , Transtornos Cognitivos/complicações , Método Duplo-Cego , Fadiga/complicações , Fadiga/tratamento farmacológico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla/complicações , Testes Neuropsicológicos/estatística & dados numéricos , Bloqueadores dos Canais de Potássio/uso terapêutico , Fatores de Tempo , Resultado do Tratamento , Adulto Jovem
20.
Int Immunopharmacol ; 75: 105776, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31351364

RESUMO

BACKGROUND: Macrophages are a primary type of innate immune cells activated in colitis. Kv1.3 channel is one of the major potassium channels in macrophages. NLRP3 inflammasome is a downstream molecule of Kv1.3 channel. PAP-1, a specific Kv1.3 channel blocker, has been shown to have immune-regulatory effects. OBJECTIVE: To investigate the effect of PAP-1 on intestinal inflammation in DSS-induced colitis and explore its possible mechanism. METHODS: C57BL/6 mice were divided into four groups: normal control group, normal+PAP-1 injection group, DSS model group, DSS model+PAP-1 injection group. Experimental colitis was induced by 5% DSS treatment; mice were injected intraperitoneally with PAP-1 from the first day for 7 consecutive days; then all mice were sacrificed, followed by isolation of colon tissue, peritoneal macrophages and spleen macrophages. The anti-inflammatory effects of PAP-1 and the expression levels of Kv1.3, iNOS, pro-IL-1ß, IL-1ß and NLRP3 inflammasome were measured. RESULTS: PAP-1 reduced DSS-induced colonic pathological damage, DAI score, MPO activity and levels of IL-1, IL-6, TNF-a, IL-18. Compared with the DSS model group, the expression of Kv1.3, iNOS, NLRP3, ASC, caspase-1p20, pro-IL-1ß and IL-1ß in colon were decreased in the DSS-induced colitis mice with PAP-1 injection. PAP-1 also reduced the expression of Kv1.3, iNOS, NLRP3, caspase-1p20 and IL-1ß on macrophages in colitis mice. CONCLUSION: PAP-1 had protective effects on DSS-induced colitis, which might be ascribed to the regulation of NLRP3 inflammasome pathway. Therefore, we found that PAP-1 was useful as a therapeutic agent in IBD and suggested a potential important role of PAP-1 in NLRP3 inflammasome-associated diseases.


Assuntos
Anti-Inflamatórios/uso terapêutico , Colite/tratamento farmacológico , Ficusina/uso terapêutico , Inflamassomos/imunologia , Canal de Potássio Kv1.3/antagonistas & inibidores , Proteína 3 que Contém Domínio de Pirina da Família NLR/imunologia , Bloqueadores dos Canais de Potássio/uso terapêutico , Animais , Anti-Inflamatórios/farmacologia , Células Cultivadas , Colite/induzido quimicamente , Colite/imunologia , Colite/patologia , Colo/efeitos dos fármacos , Colo/imunologia , Colo/patologia , Sulfato de Dextrana , Ficusina/farmacologia , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Masculino , Camundongos Endogâmicos C57BL , Bloqueadores dos Canais de Potássio/farmacologia , Transdução de Sinais/efeitos dos fármacos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA