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Potassium current voltage clamp

Richard A Gray, Pras Pathmanathan
Elucidating the underlying mechanisms of fatal cardiac arrhythmias requires a tight integration of electrophysiological experiments, models, and theory. Existing models of transmembrane action potential (AP) are complex (resulting in over parameterization) and varied (leading to dissimilar predictions). Thus, simpler models are needed to elucidate the "minimal physiological requirements" to reproduce significant observable phenomena using as few parameters as possible. Moreover, models have been derived from experimental studies from a variety of species under a range of environmental conditions (for example, all existing rabbit AP models incorporate a formulation of the rapid sodium current, INa, based on 30 year old data from chick embryo cell aggregates)...
October 2016: PLoS Computational Biology
Manuel Sánchez, Lorena Suárez, Begoña Cantabrana, Javier Bordallo
Estrogens facilitate prolactin (PRL) secretion acting on pituitary cells. In GH3 cells, estradiol induces acute action potentials and oscillations of intracellular Ca(2+) associated with the secretagogue function. Estradiol modulates several ion channels which may affect the action potential rate and the release of PRL in lactotroph cells, which might depend on its concentration. The aims were to characterize the acute effect of supraphysiological concentrations of estradiol on Ca(2+) and noninactivating K(+) currents and measure the effect on the spontaneous action potentials and PRL release in the somatolactotroph cell line, GH3...
October 17, 2016: Naunyn-Schmiedeberg's Archives of Pharmacology
Jingying Gao, Tao Bai, Lele Ren, Yaqin Ding, Xiangqin Zhong, Hui Wang, Yangyan Guo, Jie Li, Yunfeng Liu, Yi Zhang
Uncarboxylated osteocalcin, a bone matrix protein, has been proposed to regulate glucose metabolism by increasing insulin secretion, improving insulin sensitivity and stimulating β cell proliferation. Our previous study also indicated that uncarboxylated osteocalcin stimulates insulin secretion by inhibiting voltage-gated potassium (KV) channels. The goal of this study is to further investigate the underlying mechanisms for the regulation of Kv channels and insulin secretion by uncarboxylated osteocalcin. Insulin secretion and Kv channel currents were examined by radioimmunoassay and patch-clamp technique, respectively...
October 14, 2016: Peptides
Yibo Wang, Jiqing Guo, Laura L Perissinotti, James Lees-Miller, Guoqi Teng, Serdar Durdagi, Henry J Duff, Sergei Yu Noskov
Mutations that reduce inactivation of the voltage-gated Kv11.1 potassium channel (hERG) reduce binding for a number of blockers. State specific block of the inactivated state of hERG block may increase risks of drug-induced Torsade de pointes. In this study, molecular simulations of dofetilide binding to the previously developed and experimentally validated models of the hERG channel in open and open-inactivated states were combined with voltage-clamp experiments to unravel the mechanism(s) of state-dependent blockade...
October 12, 2016: Scientific Reports
Francisco J Urbano, Brennon R Luster, Stasia D'Onofrio, Susan Mahaffey, Edgar Garcia-Rill
Synaptic efferents from the PPN are known to modulate the neuronal activity of several intralaminar thalamic regions (e.g., the centrolateral/parafascicular; Cl/Pf nucleus). The activation of either the PPN or Cl/Pf nuclei in vivo has been described to induce the arousal of the animal and an increment in gamma band activity in the cortical electroencephalogram (EEG). The cellular mechanisms for the generation of gamma band oscillations in Reticular Activating System (RAS) neurons are the same as those found to generate gamma band oscillations in other brains nuclei...
2016: Journal of Visualized Experiments: JoVE
Alexandre Guet-McCreight, Olivier Camiré, Lisa Topolnik, Frances K Skinner
Determining how intrinsic cellular properties govern and modulate neuronal input-output processing is a critical endeavor for understanding microcircuit functions in the brain. However, lack of cellular specifics and nonlinear interactions prevent experiments alone from achieving this. Building and using cellular models is essential in these efforts. We focus on uncovering the intrinsic properties of mus musculus hippocampal type 3 interneuron-specific (IS3) cells, a cell type that makes GABAergic synapses onto specific interneuron types, but not pyramidal cells...
July 2016: ENeuro
Harold A Coleman, Marianne Tare, Helena C Parkington
In a number of published studies on endothelium-dependent hyperpolarization and relaxation, the results of the effects of K(+) blockers have been difficult to interpret. When the effects of two blockers have been studied, often either blocker by itself had little effect, whereas the two blockers combined tended to abolish the responses. Explanations suggested in the literature include an unusual pharmacology of the K(+) channels, and possible blocker binding interactions. In contrast, when we applied the same blockers to segments of small blood vessels under voltage-clamp, the blockers reduced the endothelium-dependent K(+) current in a linearly additive manner...
September 17, 2016: Acta Physiologica
Jun Cheng, Liang Mao, Jing Wen, Peng-Yun Li, Na Wang, Xiao-Qiu Tan, Xiao-Dong Zhang, Xiao-Rong Zeng, Liang Xu, Xian-Ming Xia, Dong Xia, Kai He, Song Su, Hui Yao, Yan Yang
BACKGROUND: Large-conductance calcium- and voltage-activated potassium channels (BKC a channels) play important roles in the maintenance of vascular tone, and their dysregulation is associated with abnormal vascular relaxation and contraction. We tested the changes in BKC a channel properties in patients at different ages to assess the effects of hypertension and aging on the functional changes of BKC a channels. METHODS AND RESULTS: Patch clamp was performed to detect the activities of BKC a channels in freshly isolated human mesenteric artery smooth muscle cells from younger patients (aged ≤45 years) without hypertension, older patients (aged ≥65 years) without hypertension, and older patients with hypertension...
September 2016: Journal of the American Heart Association
Y H Liu, Y P Wang, Y Wang, K T Ma, J Q Si, L Li
OBJECTIVE: The purpose of this paper was to study the electrophysiological properties and the type of potassium channels on cell membrane in the stria vascularis pericytes in cochlear of guinea pig. METHODS: Firstly examined the expression of the stria vascularis pericytes by desmin, a marker of pericytes, in cochlear of guinea pig with immunofluorescent method. Using whole-cell patch clamp recording techniques to observe electrophysiological properties in the cochlear pericytes in stria vascularis of guinea pig...
August 7, 2016: Zhonghua Er Bi Yan Hou Tou Jing Wai Ke za Zhi, Chinese Journal of Otorhinolaryngology Head and Neck Surgery
Namik Kaya, Maysoon Alsagob, Maria Cristina D'Adamo, Albandary Al-Bakheet, Sonia Hasan, Maria Muccioli, Faten B Almutairi, Rawan Almass, Mazhor Aldosary, Dorota Monies, Osama M Mustafa, Banan Alyounes, Rosan Kenana, Jawaher Al-Zahrani, Eva Naim, Faisal S Binhumaid, Alya Qari, Fatema Almutairi, Brian Meyer, Timothy F Plageman, Mauro Pessia, Dilek Colak, Mohammed Al-Owain
BACKGROUND: Voltage-gated potassium channels are highly diverse proteins representing the most complex class of voltage-gated ion channels from structural and functional perspectives. Deficiency of these channels usually results in various human disorders. OBJECTIVES: To describe a novel autosomal recessive syndrome associated with KCNA4 deficiency leading to congenital cataract, abnormal striatum, intellectual disability and attention deficit hyperactivity disorder...
August 31, 2016: Journal of Medical Genetics
Christoph Hönigsperger, Maximiliano J Nigro, Johan F Storm
The medial entorhinal cortex (mEC) is strongly involved in spatial navigation, memory, dementia and epilepsy. Although potassium channels shape neuronal activity, their roles in mEC are largely unknown. We used the new Kv2 blocker Guangxitoxin-1E (GTx, 10-100 nm) in rat brain slices to investigate Kv2 channel functions in mEC layer II stellate cells (SCs). These neurons project to the hippocampus and are thought to be grid cells representing space. Voltage clamp recordings from SCs nucleated patches showed that GTx inhibited a delayed rectifier K(+) current activating beyond -30 mV, but not transient, A-type current...
August 26, 2016: Journal of Physiology
L L Qian, R X Wang, M Q Sun, D Y Xia, X Tang, Y Ji, Y Wu, X Y Liu, S P Dang, Q Chai, T Lu
OBJECTIVE: To investigate the composition of potassium channels in normal rat coronary smooth muscle cells (CASMCs) and the activation effects of docosahexaenoic acid (DHA). METHODS: CASMCs were isolated by enzyme digestion.Effects of different types of potassium channel blockers and/or DHA on potassium channels currents were studied by whole-cell patch clamp technique. RESULTS: Potassium currents were significantly increased with 5 μmol/L DHA perfusion (P<0...
July 24, 2016: Zhonghua Xin Xue Guan Bing za Zhi
Z Horakova, P Matejovic, M Pasek, J Hosek, M Simurdova, J Simurda, M Bebarova
Atrial fibrillation is the most common arrhythmia at alcohol consumption. Its pathogenesis is complex, at least partly related to changes of cardiac inward rectifier potassium currents including IK1. Both ethanol and acetaldehyde have been demonstrated to considerably modify IK1 in rat ventricular myocytes. However, analogical data on the atrial IK1 are lacking. The present study aimed to analyse IK1 changes induced by ethanol and acetyldehyde in atrial myocytes. The experiments were performed by the whole cell patch-clamp technique at 23 ± 1°C on enzymatically isolated rat and guinea-pig atrial myocytes as well as on expressed human Kir2...
June 2016: Journal of Physiology and Pharmacology: An Official Journal of the Polish Physiological Society
Daniel R P Sauter, Christiane E Sørensen, Markus Rapedius, Andrea Brüggemann, Ivana Novak
Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers and new therapeutic targets are urgently needed. One of the hallmarks of cancer is changed pH-homeostasis and potentially pH-sensors may play an important role in cancer cell behavior. Two-pore potassium channels (K2P) are pH-regulated channels that conduct a background K(+) current, which is involved in setting the plasma membrane potential (Vm). Some members of the K2P superfamily were reported as crucial players in driving tumor progression...
October 2016: Biochimica et Biophysica Acta
Yi-Cheng Fu, Yu Zhang, Liu-Yang Tian, Nan Li, Xi Chen, Zhong-Qi Cai, Chao Zhu, Yang Li
OBJECTIVE: Allocryptopine (ALL) is an effective alkaloid of Corydalis decumbens (Thunb.) Pers. Papaveraceae and has proved to be anti-arrhythmic. The purpose of our study is to investigate the effects of ALL on transmural repolarizing ionic ingredients of outward potassium current (I to) and slow delayed rectifier potassium current (I Ks). METHODS: The monophasic action potential (MAP) technique was used to record the MAP duration of the epicardium (Epi), myocardium (M) and endocardium (Endo) of the rabbit heart and the whole cell patch clamp was used to record I to and I Ks in cardiomyocytes of Epi, M and Endo layers that were isolated from rabbit ventricles...
May 2016: Journal of Geriatric Cardiology: JGC
Man Zhang, Hua-Jing Yin, Wei-Ping Wang, Jiang Li, Xiao-Liang Wang
AIM: Recent studies have shown that the two-pore-domain potassium channel TREK-1 is involved in the proliferation of neural stem cells, astrocytes and human osteoblasts. In this study, we investigated how TREK-1 affected the proliferation of Chinese hamster ovary (CHO) cells in vitro. METHODS: A CHO cell line stably expressing hTREK-1 (CHO/hTREK-1 cells) was generated. TREK-1 channel currents in the cells were recorded using whole-cell voltage-clamp recording. The cell cycle distribution was assessed using flow cytometry analysis...
September 2016: Acta Pharmacologica Sinica
Markéta Bébarová, Peter Matejovič, Michal Pásek, Zuzana Hořáková, Jan Hošek, Milena Šimurdová, Jiří Šimurda
Alcohol intoxication tends to induce arrhythmias, most often the atrial fibrillation. To elucidate arrhythmogenic mechanisms related to alcohol consumption, the effect of ethanol on main components of the ionic membrane current is investigated step by step. Considering limited knowledge, we aimed to examine the effect of clinically relevant concentrations of ethanol (0.8-80 mM) on acetylcholine-sensitive inward rectifier potassium current I K(Ach). Experiments were performed by the whole-cell patch clamp technique at 23 ± 1 °C on isolated rat and guinea-pig atrial myocytes, and on expressed human Kir3...
October 2016: Naunyn-Schmiedeberg's Archives of Pharmacology
Tess Wright, Lisa N Gillespie, Stephen J O'Leary, Karina Needham
Primary auditory neurons rely on neurotrophic factors for development and survival. We previously determined that exposure to brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT3) alters the activity of hyperpolarization-activated currents (Ih) in this neuronal population. Since potassium channels are sensitive to neurotrophins, and changes in Ih are often accompanied by a shift in voltage-gated potassium currents (IK), this study examined IK with exposure to both BDNF and NT3 and the impact on firing entrainment during high frequency pulse trains...
2016: Scientific Reports
Rym Hassiki, Alain J Labro, Zakaria Benlasfar, Cécile Vincke, Mahmoud Somia, Mohamed El Ayeb, Serge Muyldermans, Dirk J Snyders, Balkiss Bouhaouala-Zahar
Voltage-gated potassium (Kv) channels form cells repolarizing power and are commonly expressed in excitable cells. In non-excitable cells, Kv channels such as Kv2.1 are involved in cell differentiation and growth. Due to the involvement of Kv2.1 in several physiological processes, these channels are promising therapeutic targets. To develop Kv2.1 specific antibody-based channel modulators, we applied a novel approach and immunized a dromedary with heterologous Ltk- cells that overexpress the mouse Kv2.1 channel instead of immunizing with channel protein fragments...
June 16, 2016: International Journal of Biological Macromolecules
Peter J Duncan, Joël Tabak, Peter Ruth, Richard Bertram, Michael J Shipston
Corticotroph cells from the anterior pituitary are an integral component of the hypothalamic-pituitary-adrenal (HPA) axis, which governs the neuroendocrine response to stress. Corticotrophs are electrically excitable and fire spontaneous single-spike action potentials and also display secretagogue-induced bursting behavior. The HPA axis function is dependent on effective negative feedback in which elevated plasma glucocorticoids result in inhibition at the level of both the pituitary and the hypothalamus. In this study, we have used an electrophysiological approach coupled with mathematical modeling to investigate the regulation of spontaneous and CRH/arginine vasopressin-induced activity of corticotrophs by glucocorticoids...
August 2016: Endocrinology
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