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ion channelopathy

Stylianos Michalakis, Elvir Becirovic, Martin Biel
The first step in vision is the absorption of photons by the photopigments in cone and rod photoreceptors. After initial amplification within the phototransduction cascade the signal is translated into an electrical signal by the action of cyclic nucleotide-gated (CNG) channels. CNG channels are ligand-gated ion channels that are activated by the binding of cyclic guanosine monophosphate (cGMP) or cyclic adenosine monophosphate (cAMP). Retinal CNG channels transduce changes in intracellular concentrations of cGMP into changes of the membrane potential and the Ca2+ concentration...
March 7, 2018: International Journal of Molecular Sciences
Kathleen T Hickey, Amir Elzomor
The discovery of the human genome has ushered in a new era of molecular testing, advancing our knowledge and ability to identify cardiac channelopathies. Genetic variations can affect the opening and closing of the potassium, sodium, and calcium channels, resulting in arrhythmias and sudden death. Cardiac arrhythmias caused by disorders of ion channels are known as cardiac channelopathies. Nurses are important members of many interdisciplinary teams and must have a general understanding of the pathophysiology of the most commonly encountered cardiac channelopathies, electrocardiogram characteristics, approaches to treatment, and care for patients and their families...
2018: AACN Advanced Critical Care
Anna Garcia-Elias, Begoña Benito
Long QT syndrome, short QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia are inherited primary electrical disorders that predispose to sudden cardiac death in the absence of structural heart disease. Also known as cardiac channelopathies, primary electrical disorders respond to mutations in genes encoding cardiac ion channels and/or their regulatory proteins, which result in modifications in the cardiac action potential or in the intracellular calcium handling that lead to electrical instability and life-threatening ventricular arrhythmias...
February 28, 2018: International Journal of Molecular Sciences
Joanna C Jen, Jijun Wan
The familial episodic ataxias (EAs) are prototypical channelopathies in the central nervous system clinically characterized by attacks of imbalance and incoordination variably associated with progressive ataxia and variable interictal features. EA1, EA2, and EA6 are caused by mutations in ion channel- and transporter-encoding genes that regulate neuronal excitability and neurotransmission.
2018: Handbook of Clinical Neurology
Boris Martinac, Kate Poole
The ability of cells to sense and respond to their physical environment is fundamental to a broad spectrum of biological processes. Cells express an array of force sensors that can transduce mechanical inputs into biochemical signals, including the mechanically activated ion channels PIEZO1, PIEZO2 and TRPV4. The identification and characterisation of mechanically activated ion channels has proven challenging, as has identifying their mode of activation and regulation in vivo. However, the diverse channelopathies associated with the known channels highlights their physiological importance...
February 20, 2018: International Journal of Biochemistry & Cell Biology
Wail Ali, Beth A Bubolz, Linh Nguyen, Danny Castro, Jorge Coss-Bu, Michael M Quach, Curtis E Kennedy, Anne E Anderson, Yi-Chen Lai
Objective: Convulsive status epilepticus can exert profound cardiovascular effects in adults including ventricular depolarization-repolarization abnormalities. Whether status epilepticus adversely affects ventricular electrical properties in children is less understood. Therefore, we sought to characterize ventricular alterations and the associated clinical factors in children following convulsive status epilepticus. Methods: We conducted a 2-year retrospective, case-control study...
December 2017: Epilepsia Open
Natalia Prevarskaya, Roman Skryma, Yaroslav Shuba
Genomic instability is a primary cause and fundamental feature of human cancer. However, all cancer cell genotypes generally translate into several common pathophysiological features, often referred to as cancer hallmarks. Although nowadays the catalog of cancer hallmarks is quite broad, the most common and obvious of them are 1) uncontrolled proliferation, 2) resistance to programmed cell death (apoptosis), 3) tissue invasion and metastasis, and 4) sustained angiogenesis. Among the genes affected by cancer, those encoding ion channels are present...
April 1, 2018: Physiological Reviews
Nabil El-Sherif, Gioia Turitto, Mohamed Boutjdir
Since its initial description by Jervell and Lange-Nielsen in 19571 , the congenital long QT syndrome (LQTS) has been the most investigated cardiac ion channelopathy. Although congenital LQTS continues to remain the domain of cardiologists, cardiac electrophysiologists, and specialized centers, the by far more frequent acquired drug-induced LQTS is the domain of all physicians and other members of the health care team who are required to make therapeutic decisions. This report will review the electrophysiological mechanisms of LQTS and TdP, electrocardiographic (ECG) characteristics of acquired LQTS, its clinical presentation, management, and future directions in the field...
February 6, 2018: Pacing and Clinical Electrophysiology: PACE
Advithi Rangaraju, Shuba Krishnan, G Aparna, Satish Sankaran, Ashraf U Mannan, B Hygriv Rao
Electrical storm (ES) is a life threatening clinical situation. Though a few clinical pointers exist, the occurrence of ES in a patient with remote myocardial infarction (MI) is generally unpredictable. Genetic markers for this entity have not been studied. In the present study, we carried out genetic screening in patients with remote myocardial infarction presenting with ES by next generation sequencing and identified 25 rare variants in 19 genes predominantly in RYR2, SCN5A, KCNJ11, KCNE1 and KCNH2, CACNA1B, CACNA1C, CACNA1D and desmosomal genes - DSP and DSG2 that could potentially be implicated in electrical storm...
January 30, 2018: Indian Pacing and Electrophysiology Journal
M Gregor Madej, Christine M Ziegler
Cryo-electron microscopy (cryo-EM) permits the determination of atomic protein structures by averaging large numbers of individual projection images recorded at cryogenic temperatures-a method termed single-particle analysis. The cryo-preservation traps proteins within a thin glass-like ice layer, making literally a freeze image of proteins in solution. Projections of randomly adopted orientations are merged to reconstruct a 3D density map. While atomic resolution for highly symmetric viruses was achieved already in 2009, the development of new sensitive and fast electron detectors has enabled cryo-EM for smaller and asymmetrical proteins including fragile membrane proteins...
January 17, 2018: Pflügers Archiv: European Journal of Physiology
Valentine Sergeev, Frances Perry, Thomas M Roston, Shubhayan Sanatani, Glen F Tibbits, Thomas W Claydon
Long QT syndrome (LQTS) is the most common cardiac ion channelopathy and has been found to be responsible for approximately 10% of sudden infant death syndrome (SIDS) cases. Despite increasing use of broad panels and now whole exome sequencing (WES) in the investigation of SIDS, the probability of identifying a pathogenic mutation in a SIDS victim is low. We report a family-based study who are afflicted by recurrent SIDS in which several members harbor a variant, p.Pro963Thr, in the C-terminal region of the human-ether-a-go-go (hERG) gene, published to be responsible for cases of LQTS type 2...
December 20, 2017: Forensic Science International
F Y Wu, L L Gai, X P Kong, B Hao, E W Huang, H Shi, L H Sheng, L Quan, S P Liu, B Luo
Due to the negative autopsy and without cardiac structural abnormalities, unexpected sudden cardiac death (USCD) is always a tough issue for forensic pathological expertise. USCD may be associated with parts of fatal arrhythmic diseases. These arrhythmic diseases may be caused by disorders of cardiac ion channels or channel-related proteins. Caveolin can combine with multiple myocardial ion channel proteins through its scaffolding regions and plays an important role in maintaining the depolarization and repolarization of cardiac action potential...
June 2017: Fa Yi Xue za Zhi
Jason Wu, Michael Young, Amanda H Lewis, Ashley N Martfeld, Breanna Kalmeta, Jörg Grandl
Piezo proteins form mechanically activated ion channels that are responsible for our sense of light touch, proprioception, and vascular blood flow. Upon activation by mechanical stimuli, Piezo channels rapidly inactivate in a voltage-dependent manner through an unknown mechanism. Inactivation of Piezo channels is physiologically important, as it modulates overall mechanical sensitivity, gives rise to frequency filtering of repetitive mechanical stimuli, and is itself the target of numerous human disease-related channelopathies that are not well understood mechanistically...
November 28, 2017: Cell Reports
Ying Wu, Hui Ma, Fan Zhang, Chunlei Zhang, Xiaohan Zou, Zhengyu Cao
Voltage-gated sodium channels (Navs) play critical roles in action potential generation and propagation. Nav channelopathy as well as pathological sensitization contribute to allodynia and hyperalgesia. Recent evidence has demonstrated the significant roles of Nav subtypes (Nav1.3, 1.7, 1.8, and 1.9) in nociceptive transduction, and therefore these Navs may represent attractive targets for analgesic drug discovery. Animal toxins are structurally diverse peptides that are highly potent yet selective on ion channel subtypes and therefore represent valuable probes to elucidate the structures, gating properties, and cellular functions of ion channels...
February 21, 2018: ACS Chemical Neuroscience
M E O'Leary, M Chahine
Voltage-gated sodium (Na(+)) channels are expressed in virtually all electrically excitable tissues and are essential for muscle contraction and the conduction of impulses within the peripheral and central nervous systems. Genetic disorders that disrupt the function of these channels produce an array of Na(+) channelopathies resulting in neuronal impairment, chronic pain, neuromuscular pathologies, and cardiac arrhythmias. Because of their importance to the conduction of electrical signals, Na(+) channels are the target of a wide variety of local anesthetic, antiarrhythmic, anticonvulsant, and antidepressant drugs...
November 15, 2017: Handbook of Experimental Pharmacology
Wang Xianpei, Wu Sha, Gao Chuanyu, Yan Juanjuan, Chen Chong, Shi Yongen, Feng Yu, Lin Zhenhao
BACKGROUND: Tpeak-Tend interval (Tp-e interval) in electrocardiogram (ECG) has been reported to predict malignant arrhythmia events (MAE) in ST-segment elevation myocardial infarction and ion channelopathy. Tp-e interval and other ECG parameters as predictors for MAE was evaluated in patients with vasospastic angina (VA). METHODS AND RESULTS: Sixty-two patients with VA (Non-MAE group) and 20 patients with VA complicated by MAE (MAE group) were enrolled in our Division of Cardiology between January 2010 and December 2015...
December 15, 2017: International Journal of Cardiology
Ivone U S Leong, Alexander Stuckey, Daniele Belluoccio, Vicky Fan, Jonathan R Skinner, Debra O Prosser, Donald R Love
Sudden cardiac death (SCD) in people before the age of 35 years is a devastating event for any family. The causes of SCD in the young can be broadly divided into two groups: heritable cardiac disorders that affect the heart structure (cardiomyopathies) and primary electrical disorders (cardiac ion channelopathies). Genetic testing is vital as those suffering from cardiac ion channelopathies have structurally normal hearts, and those with cardiomyopathies may only show subtle abnormalities in the heart and these signs may not be detected during an autopsy...
October 10, 2017: Medical Sciences: Open Access Journal
Sergey Kozlov
Ion channels are transmembrane proteins that allow passive flow of ions inside and/or outside of cells or cell organelles. Except mutations lead to nonfunctional protein production or abolished receptor entrance on the membrane surface an altered channel may have two principal conditions that can be corrected. The channel may conduct fewer ions through (loss-of-function mutations) or too many ions (gain-of-function mutations) compared to a normal channel. Toxins from animal venoms are specialised molecules that are generally oriented toward interactions with ion channels...
October 25, 2017: Neuropharmacology
Boris S Zhorov
X-ray and cryo-EM structures of tetrameric and pseudo-tetrameric P-loop channels are used to elaborate homology models of mammalian voltage-gated sodium channels with drugs and neurotoxins. Such models integrate experimental data, assist in planning new experiments, and may facilitate drug design. This chapter outlines sodium channel models with local anesthetics, anticonvulsants, and antiarrhythmics, which are used to manage pain and treat sodium channelopathies. Further summarized are sodium channel models with tetrodotoxin, mu-conotoxins, batrachotoxin, scorpion toxins, and insecticides...
September 14, 2017: Handbook of Experimental Pharmacology
Jui-Yi Hsieh, Diane M Papazian
Zebrafish is a lower vertebrate model organism that facilitates integrative analysis of the in vivo effects of potassium and other ion channel mutations at the molecular, cellular, developmental, circuit, systems, and behavioral levels of analysis. Here, we describe a method for extracellular, loose patch electrophysiological recording of electrical activity in cerebellar Purkinje cells in living, awake zebrafish, with the goal of investigating pathological mechanisms underlying channelopathies or other diseases that disrupt cerebellar function...
2018: Methods in Molecular Biology
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