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1.
Con-ciencia (La Paz) ; 8(2): 21-34, 2020. ilus.
Article in English | LILACS, LIBOCS | ID: biblio-1147979

ABSTRACT

INTRODUCCIÓN: el canal de Potasio sensible a ATP (canal KATP) regula la producción de Insulina por células ß pancreáticas. La Glibenclamida (GBM) (fármaco antidiabético) y el ATP actúan como inhibidores de este canal, mientras que el ADP lo activa. El canal KATP es un octámero constituido por 4 subunidades centrales Kir6.2 que forman el poro y 4 subunidades externas de regulación SUR1. OBJETIVO: determinar la dinámica estructural entre las conformaciones abierta y cerrada del canal KATP en células pancreáticas. MÉTODO: análisis estructural comparativo de diferentes estructuras cristalográficas del canal KATP de células pancreáticas humanas empleando el software Chimera v1.11.2 RESULTADOS: La subunidad Kir6.2 presenta un dominio de unión a PIP2 (activador), una Hélice Interfacial (IFH) y un dominio N-terminal (KNtp). Por otro lado, la subunidad SUR1 que contiene el sitio de unión a la GBM, tiene 2 Dominios de Unión a Nucleótidos (NBD1/2), un bucle M5-Lh1 y un Motivo de Lazo formado por la interface entre el Dominio Trans-membrana 0 y el Bucle 0 (TMD0-L0). Los resultados del análisis dinámico estructural mediante herramientas bioinformáticas, indican que estas regiones participan activamente en los cambios conformacionales que dan lugar al cierre (inhibición) o apertura (activación) de este canal. CONCLUSIÓN: El estudio de la dinámica de activación e inhibición de los canales KATP es imprescindible para la evaluación, descubrimiento y/o diseño de nuevos compuestos naturales, que como la GBM, puedan promover la secreción de Insulina para coadyuvar o mejorar el tratamiento de pacientes diabéticos.


INTRODUCTION: the ATP-sensitive Potassium channel (KATP channel) regulates insulin production by pancreatic ß cells. Glibenclamide (GBM) (antidiabetic drug) and ATP act as inhibitors of this channel, while ADP activates it. The KATP channel is an octamer consisting of 4 central Kir6.2 subunits that form the pore and 4 external regulation subunits SUR1. OBJECTIVE: to determine the structural dynamics between the open and closed conformations of the KATP channel in pancreatic cells. METHOD: comparative structural analysis of different crystallographic structures of the KATP channel of human pancreatic cells using Chimera v1.11.2. RESULTS: the Kir6.2 subunit has a PIP2 binding domain (activator), an Interfacial Helix (IFH) and an N-terminal domain (KNtp). On the other hand, the SUR1 subunit that contains the GBM binding site, has 2 Nucleotide Binding Domains (NBD1/2), an M5-Lh1 loop and a Lasso Motif formed by the interface between the Trans-membrane Domain 0 and Loop 0 (TMD0-L0). The results of the dynamic structural analysis using bioinformatics tools indicate that these regions participate actively in the conformational changes that lead to the closure (inhibition) or opening (activation) of this channel. CONCLUSION: the study of the dynamics of activation and inhibition of the KATP channels is essential for the evaluation, discovery and/or design of new natural compounds, which like GBM, can promote insulin secretion to aid or improve the treatment of diabetic patients.


Subject(s)
Humans , Software , Potassium Channels , Adenosine Diphosphate , Patients , Insulin
2.
Article in English | WPRIM | ID: wpr-787133

ABSTRACT

In vascular smooth muscle, K⁺ channels, such as voltage-gated K⁺ channels (Kv), inward-rectifier K⁺ channels (Kir), and big-conductance Ca²⁺-activated K⁺ channels (BK(Ca)), establish a hyperpolarized membrane potential and counterbalance the depolarizing vasoactive stimuli. Additionally, Kir mediates endothelium-dependent hyperpolarization and the active hyperemia response in various vessels, including the coronary artery. Pulmonary arterial hypertension (PAH) induces right ventricular hypertrophy (RVH), thereby elevating the risk of ischemia and right heart failure. Here, using the whole-cell patch-clamp technique, we compared Kv and Kir current densities (I(Kv) and I(Kir)) in the left (LCSMCs), right (RCSMCs), and septal branches of coronary smooth muscle cells (SCSMCs) from control and monocrotaline (MCT)-induced PAH rats exhibiting RVH. In control rats, (1) I(Kv) was larger in RCSMCs than that in SCSMCs and LCSMCs, (2) I(Kv) inactivation occurred at more negative voltages in SCSMCs than those in RCSMCs and LCSMCs, (3) I(Kir) was smaller in SCSMCs than that in RCSMCs and LCSMCs, and (4) I(BKCa) did not differ between branches. Moreover, in PAH rats, I(Kir) and I(Kv) decreased in SCSMCs, but not in RCSMCs or LCSMCs, and I(BKCa) did not change in any of the branches. These results demonstrated that SCSMC-specific decreases in I(Kv) and I(Kir) occur in an MCT-induced PAH model, thereby offering insights into the potential pathophysiological implications of coronary blood flow regulation in right heart disease. Furthermore, the relatively smaller I(Kir) in SCSMCs suggested a less effective vasodilatory response in the septal region to the moderate increase in extracellular K⁺ concentration under increased activity of the myocardium.


Subject(s)
Animals , Coronary Vessels , Heart Diseases , Heart Failure , Hyperemia , Hypertension , Hypertrophy, Right Ventricular , Ischemia , Membrane Potentials , Monocrotaline , Muscle, Smooth , Muscle, Smooth, Vascular , Myocardium , Myocytes, Smooth Muscle , Patch-Clamp Techniques , Potassium Channels , Rats , Septum of Brain
3.
Article in Chinese | WPRIM | ID: wpr-773481

ABSTRACT

OBJECTIVE@#To observe the effect of cinobufagin on transient outward potassium current () in rat dorsal root ganglion cells of cancer-induced bone pain (CIBP) and explore the possible analgesic mechanism of cinobufagin.@*METHODS@#Whole cell patch clamp technique was used to examine the effect of cionbufagin on in acutely isolated dorsal root ganglion (DRG) cells from normal SD rats and rats with bone cancer pain.@*RESULTS@#The DRG cells from rats with CIBP showed obviously decreased current density, an activation curve shift to the right, and an inactivation curve shift to the left. Cinobufagin treatment significantly increased the current density and reversed the changes in the activation and inactivation curves in the DRG cells.@*CONCLUSIONS@# current is decreased in DRG neurons from rats with CIBP. Cinobufagin can regulate the activation and inactivation of current in the DRG cells, which may be related to its analgesic mechanism.


Subject(s)
Analgesics , Pharmacology , Animals , Bufanolides , Pharmacology , Cancer Pain , Drug Therapy , Cells, Cultured , Ganglia, Spinal , Patch-Clamp Techniques , Potassium Channels , Metabolism , Rats , Rats, Sprague-Dawley
4.
Article in English | WPRIM | ID: wpr-764042

ABSTRACT

Among the environmental chemicals that may be able to disrupt the endocrine systems of animals and humans are polychlorinated biphenyls (PCBs), a chemical class of considerable concern. PCB consists of two six-carbon rings linked by a single carbon bond, and theoretically, 209 congeners can form, depending on the number of chlorines and their location on the biphenyl rings. Furthermore, 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) exposure also increases nitric oxide production and nuclear factor kappa-light-chain-enhancer of activated B cells binding activity in chondrocytes, thus contributing as an initiator of chondrocyte apoptosis and resulting in thymic atrophy and immunosuppression. This study identified whether cardiac and immune abnormalities from PCB126 were caused by the Kv1.3 and Kv1.5 channels. PCB126 did not affect either the steady-state current or peak current of the Kv1.3 and Kv1.5 channels. However, PCB126 right-shifted the steady-state activation curves of human Kv1.3 channels. These results suggest that PCBs can affect the heart in a way that does not block voltage-dependent potassium channels including Kv1.3 and Kv1.5 directly.


Subject(s)
Animals , Apoptosis , Atrophy , B-Lymphocytes , Carbon , Chondrocytes , Endocrine System , Heart , Humans , Immunosuppression , Nitric Oxide , Polychlorinated Biphenyls , Potassium Channels
5.
Article in English | WPRIM | ID: wpr-761810

ABSTRACT

Lung cancer is the most common cause of cancer deaths worldwide and several molecular signatures have been developed to predict survival in lung cancer. Increasing evidence suggests that proliferation and migration to promote tumor growth are associated with dysregulated ion channel expression. In this study, by analyzing high-throughput gene expression data, we identify the differentially expressed K⁺ channel genes in lung cancer. In total, we prioritize ten dysregulated K⁺ channel genes (5 up-regulated and 5 down-regulated genes, which were designated as K-10) in lung tumor tissue compared with normal tissue. A risk scoring system combined with the K-10 signature accurately predicts clinical outcome in lung cancer, which is independent of standard clinical and pathological prognostic factors including patient age, lymph node involvement, tumor size, and tumor grade. We further indicate that the K-10 potentially predicts clinical outcome in breast and colon cancers. Molecular signature discovered through K⁺ gene expression profiling may serve as a novel biomarker to assess the risk in lung cancer.


Subject(s)
Breast , Colonic Neoplasms , Gene Expression , Gene Expression Profiling , Humans , Ion Channels , Lung Neoplasms , Lung , Lymph Nodes , Potassium Channels , Potassium
6.
J. venom. anim. toxins incl. trop. dis ; 25: e148118, 2019. tab, ilus
Article in English | LILACS, VETINDEX | ID: biblio-1002497

ABSTRACT

Scorpion venoms are natural sources of molecules that have, in addition to their toxic function, potential therapeutic applications. In this source the neurotoxins can be found especially those that act on potassium channels. Potassium channels are responsible for maintaining the membrane potential in the excitable cells, especially the voltage-dependent potassium channels (Kv), including Kv1.3 channels. These channels (Kv1.3) are expressed by various types of tissues and cells, being part of several physiological processes. However, the major studies of Kv1.3 are performed on T cells due its importance on autoimmune diseases. Scorpion toxins capable of acting on potassium channels (KTx), mainly on Kv1.3 channels, have gained a prominent role for their possible ability to control inflammatory autoimmune diseases. Some of these toxins have already left bench trials and are being evaluated in clinical trials, presenting great therapeutic potential. Thus, scorpion toxins are important natural molecules that should not be overlooked in the treatment of autoimmune and other diseases.(AU)


Subject(s)
Animals , Scorpion Venoms/toxicity , Potassium Channels , Immunosuppression/methods
7.
Article in English | WPRIM | ID: wpr-687928

ABSTRACT

<p><b>OBJECTIVE</b>To investigate whether the methanol extract of Berberis amurensis Rupr. (BAR) augments penile erection using in vitro and in vivo experiments.</p><p><b>METHODS</b>The ex vivo study used corpus cavernosum strips prepared from adult male New Zealand White rabbits. In in vivo studies for intracavernous pressure (ICP), blood pressure, mean arterial pressure (MAP), and increase of peak ICP were continuously monitored during electrical stimulation of Sprague-Dawley rats.</p><p><b>RESULTS</b>Preconstricted with phenylephrine (PE) in isolated endotheliumintact rabbit corus cavernosum, BAR relaxed penile smooth muscle in a dose-dependent manner, which was inhibited by pretreatment with NG-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, and H-[1,2,4]-oxadiazole-[4,3-α]-quinoxalin-1-one, a soluble guanylyl cclase inhibitor. BAR significantly relaxed penile smooth muscles dose-dependently in ex vivo, and this was inhibited by pretreatment with L-NAME H-[1,2,4]-oxadiazole-[4,3-α]-quinoxalin-1-one. BAR-induced relaxation was significantly attenuated by pretreatment with tetraethylammonium (TEA, P<0.01), a nonselective K channel blocker, 4-aminopyridine (4-AP, P<0.01), a voltage-dependent K channel blocker, and charybdotoxin (P<0.01), a large and intermediate conductance Ca sensitive-K channel blocker, respectively. BAR induced an increase in peak ICP, ICP/MAP ratio and area under the curve dose dependently.</p><p><b>CONCLUSION</b>BAR augments penile erection via the nitric oxide/cyclic guanosine monophosphate system and Ca sensitive-K (BK and IK) channels in the corpus cavernosum.</p>


Subject(s)
Animals , Area Under Curve , Berberis , Chemistry , Blood Pressure , Cyclic GMP , Metabolism , Epoprostenol , Pharmacology , In Vitro Techniques , Indomethacin , Pharmacology , Male , Models, Biological , Muscle Relaxation , Muscle, Smooth , Physiology , NG-Nitroarginine Methyl Ester , Pharmacology , Nitric Oxide , Metabolism , Penile Erection , Phenylephrine , Pharmacology , Plant Extracts , Pharmacology , Potassium Channel Blockers , Pharmacology , Potassium Channels , Metabolism , Pressure , Rabbits
8.
Article in English | WPRIM | ID: wpr-716847

ABSTRACT

Permanent neonatal diabetes mellitus is most commonly caused by mutations in the ATP-sensitive potassium channel (KATP) subunits. Prompt initiation of sulfonylurea treatment can improve glycemic control in children with KCNJ11 mutation. In this report, we present a case of permanent neonatal diabetes caused by a mutation in the KCNJ11 gene that was successfully treated via early switching of insulin to sulfonylurea treatment. A 53-day-old female infant presented with diabetic ketoacidosis. Insulin was administered for the ketoacidosis and blood glucose regulation. At 3 months of age, using genomic DNA extracted from peripheral lymphocytes, direct sequencing of KCNJ11 identified a heterozygous mutation of c.158G>A (p.G53D) and confirmed the diagnosis of permanent neonatal diabetes mellitus. Subsequently, treatment with sulfonylurea was initiated, and the insulin dose was gradually tapered. At 4 months of age, insulin therapy was discontinued, and sulfonylurea (glimepiride, 0.75 mg/kg) was administered alone. At 6 months after initiation of administration of sulfonylurea monotherapy, blood glucose control was stable, and no hypoglycemic events or developmental delays were reported. C-peptide levels increased during treatment with sulfonylurea. Early switching to sulfonylurea in infants with permanent diabetes mellitus owing to a KCNJ11 mutation could successfully help regulate glycemic control, which suggests the need for early genetic testing in patients presenting with diabetes before 6 months of age.


Subject(s)
Blood Glucose , C-Peptide , Child , Diabetes Mellitus , Diabetic Ketoacidosis , Diagnosis , DNA , Female , Genetic Testing , Humans , Infant , Infant, Newborn , Insulin , Ketosis , Lymphocytes , Potassium Channels
9.
Article in English | WPRIM | ID: wpr-716768

ABSTRACT

PURPOSE: Abnormal potassium channels expression affects vessel function, including vascular tone and proliferation rate. Diverse potassium channels, including voltage-gated potassium (Kv) channels, are involved in pathological changes of pulmonary arterial hypertension (PAH). Since the role of the Kv1.7 channel in PAH has not been previously studied, we investigated whether Kv1.7 channel expression changes in the lung tissue of a monocrotaline (MCT)-induced PAH rat model and whether this change is influenced by the endothelin (ET)-1 and reactive oxygen species (ROS) pathways. METHODS: Rats were separated into 2 groups: the control (C) group and the MCT (M) group (60 mg/kg MCT). A hemodynamic study was performed by catheterization into the external jugular vein to estimate the right ventricular pressure (RVP), and pathological changes in the lung tissue were investigated. Changes in protein and mRNA levels were confirmed by western blot and polymerase chain reaction analysis, respectively. RESULTS: MCT caused increased RVP, medial wall thickening of the pulmonary arterioles, and increased expression level of ET-1, ET receptor A, and NADPH oxidase (NOX) 4 proteins. Decreased Kv1.7 channel expression was detected in the lung tissue. Inward-rectifier channel 6.1 expression in the lung tissue also increased. We confirmed that ET-1 increased NOX4 level and decreased glutathione peroxidase-1 level in pulmonary artery smooth muscle cells (PASMCs). ET-1 increased ROS level in PASMCs. CONCLUSION: Decreased Kv1.7 channel expression might be caused by the ET-1 and ROS pathways and contributes to MCT-induced PAH.


Subject(s)
Animals , Arterioles , Blotting, Western , Catheterization , Catheters , Endothelins , Glutathione , Hemodynamics , Hypertension , Jugular Veins , Lung , Models, Animal , Monocrotaline , Myocytes, Smooth Muscle , NADPH Oxidases , Polymerase Chain Reaction , Potassium , Potassium Channels , Potassium Channels, Voltage-Gated , Pulmonary Artery , Rats , Reactive Oxygen Species , RNA, Messenger , Ventricular Pressure
10.
Neuroscience Bulletin ; (6): 341-348, 2018.
Article in English | WPRIM | ID: wpr-777064

ABSTRACT

The pathogenesis of the second major neurodegenerative disorder, Parkinson's disease (PD), is closely associated with the dysfunction of potassium (K) channels. Therefore, PD is also considered to be an ion channel disease or neuronal channelopathy. Mounting evidence has shown that K channels play crucial roles in the regulations of neurotransmitter release, neuronal excitability, and cell volume. Inhibition of K channels enhances the spontaneous firing frequency of nigral dopamine (DA) neurons, induces a transition from tonic firing to burst discharge, and promotes the release of DA in the striatum. Recently, three K channels have been identified to protect DA neurons and to improve the motor and non-motor symptoms in PD animal models: small conductance (SK) channels, A-type K channels, and K7/KCNQ channels. In this review, we summarize the physiological and pharmacological effects of the three K channels. We also describe in detail the laboratory investigations regarding K channels as a potential therapeutic target for PD.


Subject(s)
Animals , Humans , Parkinson Disease , Metabolism , Potassium Channels , Metabolism
11.
Neuroscience Bulletin ; (6): 759-768, 2018.
Article in English | WPRIM | ID: wpr-777023

ABSTRACT

Cyproheptadine (CPH), a first-generation antihistamine, enhances the delayed rectifier outward K current (I) in mouse cortical neurons through a sigma-1 receptor-mediated protein kinase A pathway. In this study, we aimed to determine the effects of CPH on neuronal excitability in current-clamped pyramidal neurons in mouse medial prefrontal cortex slices. CPH (10 µmol/L) significantly reduced the current density required to generate action potentials (APs) and increased the instantaneous frequency evoked by a depolarizing current. CPH also depolarized the resting membrane potential (RMP), decreased the delay time to elicit an AP, and reduced the spike threshold potential. This effect of CPH was mimicked by a sigma-1 receptor agonist and eliminated by an antagonist. Application of tetraethylammonium (TEA) to block I channels hyperpolarized the RMP and reduced the instantaneous frequency of APs. TEA eliminated the effects of CPH on AP frequency and delay time, but had no effect on spike threshold or RMP. The current-voltage relationship showed that CPH increased the membrane depolarization in response to positive current pulses and hyperpolarization in response to negative current pulses, suggesting that other types of membrane ion channels might also be affected by CPH. These results suggest that CPH increases the excitability of medial prefrontal cortex neurons by regulating TEA-sensitive I channels as well as other TEA-insensitive K channels, probably I and inward-rectifier Kir channels. This effect of CPH may explain its apparent clinical efficacy as an antidepressant and antipsychotic.


Subject(s)
Animals , Cyproheptadine , Pharmacology , Female , Histamine H1 Antagonists , Pharmacology , Membrane Potentials , Physiology , Mice, Inbred C57BL , Patch-Clamp Techniques , Potassium Channel Blockers , Pharmacology , Potassium Channels , Metabolism , Prefrontal Cortex , Physiology , Pyramidal Cells , Physiology , Receptors, sigma , Metabolism , Tetraethylammonium , Pharmacology , Tissue Culture Techniques
12.
Neuroscience Bulletin ; (6): 887-900, 2018.
Article in English | WPRIM | ID: wpr-777005

ABSTRACT

General anesthesia is an unconscious state induced by anesthetics for surgery. The molecular targets and cellular mechanisms of general anesthetics in the mammalian nervous system have been investigated during past decades. In recent years, K channels have been identified as important targets of both volatile and intravenous anesthetics. This review covers achievements that have been made both on the regulatory effect of general anesthetics on the activity of K channels and their underlying mechanisms. Advances in research on the modulation of K channels by general anesthetics are summarized and categorized according to four large K channel families based on their amino-acid sequence homology. In addition, research achievements on the roles of K channels in general anesthesia in vivo, especially with regard to studies using mice with K channel knockout, are particularly emphasized.


Subject(s)
Anesthetics, General , Pharmacology , Therapeutic Uses , Animals , Humans , Potassium Channels , Metabolism
13.
Article in English | WPRIM | ID: wpr-772307

ABSTRACT

The hyphal development of Candida albicans (C. albicans) has been considered as an essential virulent factor for host cell damage. However, the missing link between hyphae and virulence of C. albicans is also been discovered. Here, we identified that the null mutants of ERG3 and ERG11, two key genes in ergosterol biosynthesis pathway, can form typical hyphae but failed to cause the oral mucosal infection in vitro and in vivo for the first time. In particular, the erg3Δ/Δ and erg11Δ/Δ strains co-cultured with epithelial cells significantly reduced the adhesion, damage, and cytokine (interleukin-1α (IL-1α)) production, whereas the invasion was not affected in vitro. Importantly, they were incapable of extensive hyphal invasion, formation of micro-abscesses, and tongue epithelium damage compared to wild type due to the decrease of the colonization and epithelial infection area in a murine oropharyngeal candidiasis model. The fluconazole (FLC), an antifungal targeted at ergosterol biosynthesis, relieved the epithelial infection of C. albicansin vitro and in vivo even under non-growth inhibitory dosage confirming the virulent contribution of ergosterol biosynthesis pathway. The erg3Δ/Δ and erg11Δ/Δ strains were cleared by macrophages similar to wild type, whereas their virulence factors including agglutinin-like sequence 1 (Als1), secreted aspartyl proteinase 6 (Sap6), and hyphal wall protein-1 (Hwp1) were significantly reduced indicated that the non-toxicity might not result from the change on immune tolerance but the defective virulence. The incapacity of erg3Δ/Δ and erg11Δ/Δ in epithelial infection highlights the contribution of ergosterol biosynthesis pathway to C. albicans pathogenesis and fluconazole can not only eliminate the fungal pathogens but also reduced their virulence even at low dosage.


Subject(s)
Animals , Antifungal Agents , Pharmacology , Candida albicans , Genetics , Virulence , Candidiasis, Oral , Drug Therapy , Genetics , Microbiology , Fluconazole , Pharmacology , Genes, Fungal , Genetics , Mice , Microscopy, Electron, Scanning , Potassium Channels , Genetics , Virulence
14.
Article in English | WPRIM | ID: wpr-740746

ABSTRACT

BACKGROUND/AIMS: This study was designed to investigate the effect of Fengliao-Changweikang (FLCWK) in diarrhea-predominant irritable bowel syndrome (IBS-D) rats and explore its underlying mechanisms. METHODS: IBS-D model rats were induced by neonatal maternal separation (NMS) combined with restraint stress (RS). In in vivo experiments, the model rats were randomly divided into 5 groups: NMS + RS, FLCWK (low dose, middle dose, and high dose), and pinaverium bromide. The normal control (no handling) rats were classified as the NH group. The therapeutic effect of FLCWK was evaluated by fecal characteristics, electromyographic response and abdominal withdrawal reflex scores. In in vitro experiments, the model rats were randomly divided into 2 groups: NMS + RS, FLCWK (middle dose), and no handling rats were used as the NH group. The differences in basic tension and ACh-induced tension of isolated colonic longitudinal smooth muscle strips (CLSMs) among the 3 groups were observed. In addition, different inhibitors (nifedipine, TMB-8, L-NAME, methylene blue, and 4-AP) were pretreated to explore the underlying mechanisms. RESULTS: In in vivo experiments, fecal characteristics, electromyographic response, and abdominal withdrawal reflex scores significantly improved in the FLCWK group, compared with the NMS + RS group. In in vitro experiments, the basic tension and ACh-induced tension of CLSMs in IBS-D rats were significantly inhibited by FLCWK. After pre-treatment with different inhibitors, the ACh-induced tension of CLSMs in each group showed no significant difference. CONCLUSIONS: FLCWK manifested curative effect in IBS-D rats by inhibiting colonic contraction. The underlying mechanisms may be related to regulatory pathway of nitric oxide/cGMP/Ca2+ and specific potassium channels.


Subject(s)
Animals , Colon , Gastrointestinal Motility , Herbal Medicine , In Vitro Techniques , Irritable Bowel Syndrome , Methylene Blue , Muscle, Smooth , NG-Nitroarginine Methyl Ester , Nitric Oxide , Potassium Channels , Rats , Reflex
15.
Yonsei Medical Journal ; : 279-286, 2018.
Article in English | WPRIM | ID: wpr-713092

ABSTRACT

PURPOSE: The mechanisms underlying repolarization abnormalities during pregnancy are not fully understood. Although maternal serotonin (5-hydroxytryptamine, 5-HT) production is an important determinant for normal fetal development in mice, its role in mothers remains unclear. We evaluated the role of serotonin in ventricular repolarization in mice hearts via 5Htr3 receptor (Htr3a) and investigated the mechanism of QT-prolongation during pregnancy. MATERIALS AND METHODS: We measured current amplitudes and the expression levels of voltage-gated K⁺ (Kv) channels in freshly-isolated left ventricular myocytes from wild-type non-pregnant (WT-NP), late-pregnant (WT-LP), and non-pregnant Htr3a homozygous knockout mice (Htr3a(−/−)-NP). RESULTS: During pregnancy, serotonin and tryptophan hydroxylase 1, a rate-limiting enzyme for the synthesis of serotonin, were markedly increased in hearts and serum. Serotonin increased Kv current densities concomitant with the shortening of the QT interval in WT-NP mice, but not in WT-LP and Htr3a(−/−)-NP mice. Ondansetron, an Htr3 antagonist, decreased Kv currents in WT-LP mice, but not in WT-NP mice. Kv4.3 directly interacted with Htr3a, and this binding was facilitated by serotonin. Serotonin increased the trafficking of Kv4.3 channels to the cellular membrane in WT-NP. CONCLUSION: Serotonin increases repolarizing currents by augmenting Kv currents. Elevated serotonin levels during pregnancy counterbalance pregnancy-related QT prolongation by facilitating Htr3-mediated Kv currents.


Subject(s)
Action Potentials/drug effects , Animals , Cell Membrane/drug effects , Disease Models, Animal , Electrocardiography , Female , HSC70 Heat-Shock Proteins/metabolism , HSP90 Heat-Shock Proteins/metabolism , Heart Ventricles/drug effects , Mice, Inbred C57BL , Mice, Knockout , Myocytes, Cardiac/drug effects , Potassium Channels/metabolism , Pregnancy , Rabbits , Rats, Sprague-Dawley , Receptors, Serotonin, 5-HT3/metabolism , Serotonin/metabolism , Serotonin 5-HT3 Receptor Agonists/pharmacology
16.
Article in English | WPRIM | ID: wpr-741734

ABSTRACT

OBJECTIVE: Corticotropin-releasing hormone (CRH) is a crucial regulator of human pregnancy and parturition. Adenosine triphosphate (ATP)-sensitive potassium (KATP) channels are important for regulating myometrial quiescence during pregnancy. We investigated regulatory effects of different concentrations of CRH on KATP channel expression in human myometrial smooth muscle cells (HSMCs) in in vitro conditions. METHODS: After treating HSMCs with different concentrations of CRH (1, 10, 102, 103, 104 pmol/L), mRNA and protein expression of KATP channel subunits (Kir6.1 and SUR2B) was analyzed by reverse transcription-polymerase chain reaction and western blot. We investigated which CRH receptor was involved in the reaction and measured the effects of CRH on intracellular Ca2+ concentration when oxytocin was administered in HSMCs using Fluo-8 AM ester. RESULTS: When HSMCs were treated with low (1 pmol/L) and high (103, 104 pmol/L) CRH concentrations, KATP channel expression significantly increased and decreased, respectively. SUR2B mRNA expression at low and high CRH concentrations was significantly antagonized by antalarmin (CRH receptor-1 antagonist) and astressin 2b (CRH receptor-2 antagonist), respectively; however, Kir6.1 mRNA expression was not affected. After oxytocin treatment, the intracellular Ca2+ concentration in CRH-treated HSMCs was significantly lowered in low concentration of CRH (1 pmol/L), but not in high concentration of CRH (103 pmol/L), compared to control. CONCLUSION: Our data demonstrated the regulatory effect was different when HSMCs were treated with low (early pregnancy-like) and high (labor-like) CRH concentrations and the KATP channel expression showed significant increase and decrease. This could cause inhibition and activation, respectively, of uterine muscle contraction, demonstrating opposite dual actions of CRH.


Subject(s)
Adenosine Triphosphate , Adenosine , Animals , Blotting, Western , Corticotropin-Releasing Hormone , Female , Humans , In Vitro Techniques , KATP Channels , Mice , Myocytes, Smooth Muscle , Myometrium , Oxytocin , Parturition , Potassium Channels , Potassium , Pregnancy , Receptors, Corticotropin-Releasing Hormone , RNA, Messenger
17.
J. appl. oral sci ; 26: e20180048, 2018. graf
Article in English | LILACS, BBO | ID: biblio-954519

ABSTRACT

Abstract Objective: Periodontitis is associated with endothelial dysfunction, which is clinically characterized by a reduction in endothelium-dependent relaxation. However, we have previously shown that impairment in endothelium-dependent relaxation is transient. Therefore, we evaluated which mediators are involved in endothelium-dependent relaxation recovery. Material and methods: Rats were subjected to ligature-induced experimental periodontitis. Twenty-one days after the procedure, the animals were prepared for blood pressure recording, and the responses to acetylcholine or sodium nitroprusside were obtained before and 30 minutes after injection of a nitric oxide synthase inhibitor (L-NAME), cyclooxygenase inhibitor (Indomethacin, SC-550 and NS- 398), or calcium-dependent potassium channel blockers (apamin plus TRAM- 34). The maxilla and mandible were removed for bone loss analysis. Blood and gingivae were obtained for C-reactive protein (CRP) and myeloperoxidase (MPO) measurement, respectively. Results: Experimental periodontitis induces bone loss and an increase in the gingival MPO and plasmatic CRP. Periodontitis also reduced endothelium-dependent vasodilation, a hallmark of endothelial dysfunction, 14 days after the procedure. However, the response was restored at day 21. We found that endothelium-dependent vasodilation at day 21 in ligature animals was mediated, at least in part, by the activation of endothelial calcium-activated potassium channels. Conclusions: Periodontitis induces impairment in endothelial-dependent relaxation; this impairment recovers, even in the presence of periodontitis. The recovery is mediated by the activation of endothelial calcium-activated potassium channels in ligature animals. Although important for maintenance of vascular homeostasis, this effect could mask the lack of NO, which has other beneficial properties.


Subject(s)
Animals , Male , Periodontitis/physiopathology , Periodontitis/metabolism , Vasodilation/physiology , Potassium Channels/metabolism , Prostaglandin-Endoperoxide Synthases/metabolism , Nitric Oxide/metabolism , Time Factors , Vasodilation/drug effects , Vasodilator Agents/pharmacology , C-Reactive Protein/analysis , Nitroprusside/pharmacology , Potassium Channels/drug effects , Acetylcholine/pharmacology , Random Allocation , Alveolar Bone Loss/physiopathology , Alveolar Bone Loss/metabolism , Cyclooxygenase Inhibitors/pharmacology , Prostaglandin-Endoperoxide Synthases/drug effects , Rats, Wistar , Peroxidase/analysis , NG-Nitroarginine Methyl Ester/pharmacology , Potassium Channel Blockers/pharmacology , Arterial Pressure/drug effects , Arterial Pressure/physiology , Ligation
18.
Braz. j. med. biol. res ; 50(9): e5765, 2017. tab, graf
Article in English | LILACS | ID: biblio-888990

ABSTRACT

Clobenzorex is a metabolic precursor of amphetamine indicated for the treatment of obesity. Amphetamines have been involved with cardiovascular side effects such as hypertension and pulmonary arterial hypertension. The aim of the present study was to investigate whether the direct application of 10-9-10-5 M clobenzorex on isolated phenylephrine-precontracted rat aortic rings produces vascular effects, and if so, what mechanisms may be involved. Clobenzorex produced an immediate concentration-dependent vasorelaxant effect at the higher concentrations (10-7.5-10-5 M). The present outcome was not modified by 10-6 M atropine (an antagonist of muscarinic acetylcholine receptors), 3.1×10-7 M glibenclamide (an ATP-sensitive K+ channel blocker), 10-3 M 4-aminopyridine (4-AP; a voltage-activated K+ channel blocker), 10-5 M indomethacin (a prostaglandin synthesis inhibitor), 10-5 M clotrimazole (a cytochrome P450 inhibitor) or 10-5 M cycloheximide (a general protein synthesis inhibitor). Contrarily, the clobenzorex-induced vasorelaxation was significantly attenuated (P<0.05) by 10-5 M L-NAME (a direct inhibitor of nitric oxide synthase), 10-7 M ODQ (an inhibitor of nitric oxide-sensitive guanylyl cyclase), 10-6 M KT 5823 (an inhibitor of protein kinase G), 10-2 M TEA (a Ca2+-activated K+ channel blocker and non-specific voltage-activated K+ channel blocker) and 10-7 M apamin plus 10-7 M charybdotoxin (blockers of small- and large-conductance Ca2+-activated K+ channels, respectively), and was blocked by 8×10-2 M potassium (a high concentration) and removal of the vascular endothelium. These results suggest that the direct vasorelaxant effect by clobenzorex on phenylephrine-precontracted rat aortic rings involved stimulation of the NO/cGMP/PKG/Ca2+-activated K+ channel pathway.


Subject(s)
Animals , Male , Rats , Amphetamines/pharmacology , Aorta, Thoracic/drug effects , Endothelium, Vascular/drug effects , Vasodilation , Vasodilator Agents/pharmacology , Calcium Channels/drug effects , Calcium Channels/metabolism , Nitric Oxide Synthase Type III/drug effects , Nitric Oxide Synthase Type III/metabolism , Potassium Channels, Voltage-Gated/drug effects , Potassium Channels, Voltage-Gated/metabolism , Potassium Channels/drug effects , Potassium Channels/metabolism , Rats, Wistar
19.
Article in English | WPRIM | ID: wpr-182386

ABSTRACT

Permanent neonatal diabetes mellitus (PNDM) is caused by mutations in the ATP-sensitive potassium channel (K(ATP) channel) subunits. Developmental delay, epilepsy, and neonatal diabetes (DEND) syndrome is the most severe form of PNDM and is characterized by various neurologic features. We report on a patient with DEND syndrome following initial misdiagnosis with type 1 DM, who was successfully switched from insulin to sulfonylurea therapy. A 50-day-old male presented with fever and seizure, complicated by persistent hyperglycemia. Insulin therapy was initiated. At 10 months of age, the patient was unable to hold his head up and make eye contact with others. At 17.9 years of age, direct sequencing of KCNJ11 identified a heterozygous mutation of c.602G>A (p.R201H). Since then, treatment with gliclazide was initiated and the insulin dose was gradually reduced. Following 3 months, insulin was discontinued with a gliclazide dose of 2.4 mg/kg. The patient continued to have excellent glycemic control with a glycated hemoglobin (HbA1c) level of 5.8% after 5 months. However, the patient's psychomotor retardation did not improve. This study reports the first case of DEND syndrome in Korea caused by a KCNJ11 mutation and emphasizes the necessity to screen mutations in KATP channel genes in patients with neonatal diabetes.


Subject(s)
Diabetes Mellitus , Diagnostic Errors , Epilepsy , Fever , Gliclazide , Head , Glycated Hemoglobin A , Humans , Hyperglycemia , Insulin , Korea , Male , Potassium Channels , Seizures
20.
Acta Physiologica Sinica ; (6): 109-121, 2017.
Article in Chinese | WPRIM | ID: wpr-348293

ABSTRACT

Growth differentiation factor-15 (GDF-15) is a member of the transforming growth factor beta superfamily. GDF-15 expression is dramatically upregulated during acute brain injury, cancer, cardiovascular disease, and inflammation, suggesting its potential value as a disease biomarker. It has been suggested that GDF-15 has neurotropic effects in the nervous system. Our studies showed that GDF-15 modulated the expression of neuronal Kand Caion channels and increased the release of excitatory transmitter in the medial prefrontal cortex of mice. GDF-15 is also involved in the complex modulation of cancer and cardiovascular disease. Here, we reviewed studies involving the modulation of GDF-15 expression and its mechanisms, the primary pathological and physiological functions of GDF-15 in neurological and cardiovascular systems, and its role in cancer progression. The biological effects and the values of GDF-15 in basic research and clinical applications were also addressed.


Subject(s)
Animals , Brain Injuries , Calcium Channels , Metabolism , Cardiovascular Diseases , Disease Progression , Growth Differentiation Factor 15 , Metabolism , Humans , Inflammation , Mice , Neoplasms , Nervous System , Metabolism , Potassium Channels , Metabolism , Prefrontal Cortex , Metabolism , Transforming Growth Factor beta , Up-Regulation
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