voltage gated potassium channel

Caspr2 and TAG-1 are cell adhesion molecules (CAMs) associated with the voltage-gated potassium channels Kv1.1/1.2 at regions controlling axonal excitability, the axon initial segment (AIS) and juxtaparanodes of myelinated axons. The distribution of Kv1 at juxtaparanodes requires axo-glial contacts mediated by Caspr2 and TAG-1. In the present study, we showed that TAG-1 strongly co-localizes with Kv1.2 at the AIS of cultured hippocampal neurons whereas Caspr2 is uniformly expressed along the axolemma. Live-cell imaging revealed that Caspr2 and TAG-1 are sorted together in axonal transport vesicles...

Venom peptides are natural ligands of ion channels and have been used extensively in pharmacological characterization of various ion channels and receptors. In this chapter, we survey all known venom peptide ion-channel modulators. Our survey reveals that the majority of venom peptides characterized to date target voltage-gated sodium or potassium channels. We further find that the majority of these peptides are found in scorpion and spider venoms. We discuss the influence of the pharmacological tools available in biasing discovery and the classical "toxin-to-sequence" approach to venom peptide biodiscovery...

INTRODUCTION: Immune dysregulation associated encephalopathies present with significant psychiatric manifestations and only a few soft neurological and general systemic features. They are generally resistant to treatment with psychiatric medications. Generalized orthostatic myoclonus and faciobrachial dystonic seizures are mistaken as Creutzfeldt-Jakob disease and subacute sclerosing panencephalitis. PATIENTS AND METHODS: Forty-two patients seen during 2010-2015 and diagnosed as noninfective encephalopathy were analyzed...

AIM: Atrial fibrillation is the most common persistent cardiac arrhythmia, and it is not well controlled by present drugs. Because some resin acids open voltage-gated potassium channels and reduce neuronal excitability, we explored the effects of the resin acid isopimaric acid (IPA) on action potentials and ion currents in cardiomyocytes. METHODS: Spontaneously beating mouse atrial HL-1 cells were investigated with the whole-cell patch-clamp technique. RESULTS: 1-25 μmol L(-1) IPA reduced the action potential frequency by up to 50%...

Numerous experiments using ex vivo electrophysiology suggest that mammalian learning and memory involves regulation of voltage-gated ion channels in terms of changes in function. Yet, little is known about learning-related regulation of voltage-gated ion channels in terms of changes in expression. In two experiments, we examined changes in cell surface expression of the voltage-gated potassium channel alpha-subunit Kv1.2 in a discrete region of cerebellar cortex after eyeblink conditioning (EBC), a well-studied form of cerebellar-dependent learning...

BACKGROUND: Autoimmune voltage-gated potassium channelopathies have been associated with a range of neurological presenting symptoms, including central, peripheral, and autonomic dysfunction. PATIENT DESCRIPTION: We describe a 12-year-old boy who presented with nine months of pain, anxiety, and 30-pound weight loss. He was admitted for failure to thrive, then noted to be persistently hypertensive and tachycardic. Plasma metanephrines and urine metanephrines and catecholamines were elevated...

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Benign familial neonatal convulsion is a rare autosomal dominant inherited epilepsy syndrome characterized by unprovoked seizures in the first few days of life, normal psychomotor development, and a positive intergenerational family history of neonatal seizures. Over 90% of the affected individuals have inherited causal mutations in KCNQ2, which encodes for the potassium voltage-gated channel subfamily Q, member 2. Mutations in KCNQ2 are also associated with a severe neonatal encephalopathy phenotype associated with poor seizure control and neurodevelopmental deficits...

Covering: 1996-December 2016The human Ether-à-go-go Related Gene (hERG) channel is a voltage-gated potassium channel playing an essential role in the normal electrical activity in the heart. It is involved in the repolarization and termination of action potentials in excitable cardiac cells. Mutations in the hERG gene and hERG channel blockage by small molecules are associated with increased risk of fatal arrhythmias. Several drugs have been withdrawn from the market due to hERG channel-related cardiotoxicity...

Neurons are highly polarized cells with apparent functional and morphological differences between dendrites and axon. A critical determinant for the molecular and functional identity of axonal and dendritic segments is the restricted expression of voltage-gated ion channels (VGCs). Several studies show an uneven distribution of ion channels and their differential regulation within dendrites and axons, which is a prerequisite for an appropriate integration of synaptic inputs and the generation of adequate action potential (AP) firing patterns...

The voltage-gated K(+) channel Kv2.1 has been intimately linked with neuronal apoptosis. After ischemic, oxidative, or inflammatory insults, Kv2.1 mediates a pronounced, delayed enhancement of K(+) efflux, generating an optimal intracellular environment for caspase and nuclease activity, key components of programmed cell death. This apoptosis-enabling mechanism is initiated via Zn(2+)-dependent dual phosphorylation of Kv2.1, increasing the interaction between the channel's intracellular C-terminus domain and the SNARE protein syntaxin 1A...

BACKGROUND: Resveratrol is a polyphenolic compound extracted from plants and is also a constituent of red wine. Resveratrol produces relaxation of vascular smooth muscle and may prevent cardiovascular diseases. Although resveratrol has been reported to cause relaxation of the guinea pig gallbladder, limited data are available about the effect of resveratrol on the gallbladder smooth muscle in humans. The purpose of this study was to investigate the relaxation effects of resveratrol in human gallbladder muscle strips...

Aconitum diterpene alkaloids are known for their remarkable toxicity, which is due to their effect on ion channels. Activation of voltage-gated Na(+) channels is the major cause of their cardiotoxicity, however, influence on K(+) channels may also play a role in the overall effect.Here we report the synthesis of a series of lipo-alkaloids, including four new compounds, based on the 14-benzoylaconine structure, which is the core of a vast number of diterpene alkaloids naturally occurring in Aconitum species...

Colorectal cancer (CRC) is among the leading causes of cancer-related death throughout the world. Aberrant expression of voltage-gated potassium ion channel molecule Kv1.3 has been reported in various cancers. To explore the expression and regulation of Kv1.3 in colorectal cancer, 7 colorectal cancer cell lines and 147 cases of primary colorectal cancer were involved in this study. Kv1.3 was expressed in LOVO and SW480 cells and loss of expression was found in RKO, DLD1, SW620, HCT116, and HT29 cells. Complete methylation was found in RKO, DLD1, SW620, HCT116, and HT29 cells, partial methylation was found in LOVO and SW480 cells...

The detection of cool temperatures is thought to be mediated by primary afferent neurons that express the cool temperature sensing protein Transient Receptor Potential Cation Channel, Subfamily M, Member 8 (TRPM8). Using mice, this study tested the hypothesis that sex differences in sensitivity to cool temperatures were mediated by differences in neurons that express TRPM8. Ion currents from TRPM8 expressing trigeminal ganglion (TRG) neurons in females demonstrated larger hyperpolarization-activated cyclic nucleotide-gated currents (Ih) than male neurons at both 30° and 18°C...

The autosomal dominant spinocerebellar ataxias (SCAs) are a diverse group of neurological disorders anchored by the phenotypes of motor incoordination and cerebellar atrophy. Disease heterogeneity is appreciated through varying comorbidities: dysarthria, dysphagia, oculomotor and/or retinal abnormalities, motor neuron pathology, epilepsy, cognitive impairment, autonomic dysfunction, and psychiatric manifestations. Our study focuses on SCA13, which is caused by several allelic variants in the voltage-gated potassium channel KCNC3 (Kv3...

Lidocaine is known to inhibit the hyperpolarization-activated mixed cation current (Ih) in cardiac myocytes and neurons, as well in cells transfected with cloned Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels. However, the molecular mechanism of Ih inhibition by this drug has been limitedly explored. Here, we show that inhibition of Ih by lidocaine, recorded from Chinese hamster ovary (CHO) cells expressing the HCN1 channel, reached a steady state within one minute and was reversible. Lidocaine inhibition of Ih was greater at less negative voltages and smaller current amplitudes whereas the voltage-dependence of Ih activation was unchanged...

EAG-like (ELK) voltage-gated potassium channels are abundantly expressed in the brain. These channels exhibit a behavior called voltage-dependent potentiation (VDP), which appears to be a specialization to dampen the hyperexitability of neurons. VDP manifests as a potentiation of current amplitude, hyperpolarizing shift in voltage sensitivity, and slowing of deactivation in response to a depolarizing prepulse. Here we show that VDP of D. rerio ELK channels involves the structural interaction between the intracellular N-terminal eag domain and C-terminal CNBHD...

We utilise a clinical case to highlight why exclusion of voltage-gated potassium channel (VGKC)-complex autoantibody testing in serological evaluation of patients may delay or miss the diagnosis. A 68-year-old man presented with increasing involuntary movements consistent with faciobrachial dystonic seizures (FBDS). Initial evaluation demonstrated VGKC antibody seropositivity with leucine-rich glioma-inactivated 1 (LGI1) and contactin-associated protein-like 2 (CASPR2) seronegativity. Aggressive immunotherapy with methylprednisolone and plasmapheresis was started early in the course of his presentation...

Sulfur-containing gaseous signal molecules including hydrogen sulfide (H2 S) and sulfur dioxide (SO2 ) were previously recognized as toxic gases. However, extensive studies have revealed that they can be generated in the cardiovascular system via a sulfur-containing amino acid metabolic pathway, playing an important part in cardiovascular physiology and pathophysiology. Ion channels are pore-forming membrane proteins present in the membrane of all biological cells; functions include establishing a resting membrane potential and controlling action potentials and other electrical signals by conducting ions across the cell membrane...