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Single channel patch clamp

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https://www.readbyqxmd.com/read/28900735/4-chloro-3-nitro-n-butylbenzenesulfonamide-acts-on-kv3-1-channels-by-an-open-channel-blocker-mechanism
#1
Carlos Alberto Zanutto Bassetto Junior, Wamberto Antonio Varanda, Eduardo René Pérez González
The effects of 4-chloro-3-nitro-N-butylbenzenesulfonamide (SMD2) on KV3.1 channels, heterologous expressed in L-929 cells, were studied with the whole cell patch-clamp technique. SMD2 blocks KV3.1 in a reversible and use-dependent manner, with IC50 around 10 µM, and a Hill coefficient around 2. Although the conductance vs. voltage relationship in control condition can be described by a single Boltzmann function, two terms are necessary to describe the data in the presence of SMD2. The activation and deactivation time constants are weakly voltage dependent both for control and in the presence of SMD2...
September 12, 2017: Amino Acids
https://www.readbyqxmd.com/read/28893911/molecular-and-functional-characterization-of-the-endothelial-atp-sensitive-potassium-channel
#2
Qadeer Aziz, Yiwen Li, Naomi Anderson, Leona Ojake, Elena Tsisanova, Andrew Tinker
ATP-sensitive potassium (KATP) channels are widely expressed in the cardiovascular system where they regulate a range of biological activities by linking cellular metabolism with membrane excitability. KATP channels in vascular smooth muscle have a well-defined role in regulating vascular tone. KATP channels are also thought to be expressed in vascular endothelial cells (ECs), but their presence and function in this context is less clear. As a result, we aimed to investigate the molecular composition and physiological role of endothelial KATP channels...
September 11, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28885682/selective-targeting-of-m-type-potassium-channel-kv7-4-demonstrates-its-key-role-in-regulating-of-dopaminergic-neuronal-excitability-and-depression-like-behaviour
#3
Li Li, Hui Sun, Jie Ding, Chenxu Niu, Min Su, Ludi Zhang, Yingmin Li, Chuan Wang, Nikita Gamper, Xiaona Du, Hailin Zhang
BACKGROUND AND PURPOSE: The mesolimbic dopamine (DA) system originating in the ventral tegmental area (VTA) is implicated in the development of depression, and firing patterns of VTA DA neurons are key determinants in this process. Here, we describe a crucial role of the M-type potassium channel Kv7.4 in modulation of VTA DA neuronal excitability and in the development of depressive behaviour in mice. EXPERIMENTAL APPROACH: We used Kv7.4 knock-out mice and a social defeat model of depression in combination with various electrophysiological techniques (patch clamp recording and in vivo single unit recordings), immunohistochemistry, single-cell PCR and behavioural analyses (social interaction time and glucose preference tests) to investigate VTA circuits involved in development of depression-like behaviour...
September 8, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28882752/mechanosensitive-ion-channels-msics-in-articular-nociceptors-drive%C3%A2-mechanical-allodynia-in-osteoarthritis-oa
#4
B H He, M Christin, S Mouchbahani-Constance, A Davidova, R Sharif-Naeini
OBJECTIVE: Osteoarthritis (OA) is a disabling and highly prevalent condition affecting millions worldwide. Pain is the major complaint of OA patients and is presently inadequately managed. It manifests as mechanical allodynia, a painful response to innocuous stimuli such as joint movement. Allodynia is due in part to the sensitization of articular nociceptors to mechanical stimuli. These nociceptors respond to noxious mechanical stimuli applied to their terminals via the expression of depolarizing high-threshold mechanosensitive ion channels (MSICs) that convert painful mechanical forces into electrical signals...
September 5, 2017: Osteoarthritis and Cartilage
https://www.readbyqxmd.com/read/28874774/current-direction-amplitude-dependent-single-channel-gating-kinetics-of-mouse-pannexin-1-channel-a-new-concept-for-gating-kinetics
#5
Takeshi Nomura, Akiyuki Taruno, Makoto Shiraishi, Takashi Nakahari, Toshio Inui, Masahiro Sokabe, Douglas C Eaton, Yoshinori Marunaka
The detailed single-channel gating kinetics of mouse pannexin 1 (mPanx1) remains unknown, although mPanx1 is reported to be a voltage-activated anion-selective channel. We investigated characteristics of single-channel conductances and opening and closing rates of mPanx1 using patch-clamp techniques. The unitary current of mPanx1 shows outward rectification with single-channel conductances of ~20 pS for inward currents and ~80 pS for outward currents. The channel open time for outward currents (Cl(-) influx) increases linearly as the amplitude of single channel currents increases, while the open time for inward currents (Cl(-) efflux) is constant irrespective of changes in the current amplitude, as if the direction and amplitude of the unitary current regulates the open time...
September 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28863150/a-single-markov-type-kinetic-model-accounting-for-the-macroscopic-currents-of-all-human-voltage-gated-sodium-channel-isoforms
#6
Pietro Balbi, Paolo Massobrio, Jeanette Hellgren Kotaleski
Modelling ionic channels represents a fundamental step towards developing biologically detailed neuron models. Until recently, the voltage-gated ion channels have been mainly modelled according to the formalism introduced by the seminal works of Hodgkin and Huxley (HH). However, following the continuing achievements in the biophysical and molecular comprehension of these pore-forming transmembrane proteins, the HH formalism turned out to carry limitations and inconsistencies in reproducing the ion-channels electrophysiological behaviour...
September 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28862328/an-allosteric-gating-model-recapitulates-the-biophysical-properties-of-ik-l-expressed-in-mouse-vestibular-type-i-hair-cells
#7
Paolo Spaiardi, Elisa Tavazzani, Marco Manca, Veronica Milesi, Giancarlo Russo, Ivo Prigioni, Walter Marcotti, Jacopo Magistretti, Sergio Masetto
Type I and Type II hair cells are the sensory receptors of the mammalian vestibular epithelia. Type I hair cells are characterized by their basolateral membrane being enveloped in a single large afferent nerve terminal, named calyx, and by the expression of a low-voltage-activated outward rectifying K(+) current, IK,L . The biophysical properties and molecular profile of IK,L are still largely unknown. By using the patch-clamp whole-cell technique, we examined the voltage- and time-dependent properties of IK,L in Type I hair cells of the mouse semicircular canal...
September 1, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28855948/astragalus-granule-prevents-ca-2-current-remodeling-in-heart-failure-by-the-downregulation-of-camkii
#8
Sinai Li, Yibing Nong, Qun Gao, Jing Liu, Yan Li, Xiaoyun Cui, Jie Wan, Jinjin Lu, Mingjie Sun, Qian Wu, Xiaolu Shi, Haifeng Cui, Weihong Liu, Mingxue Zhou, Lina Li, Qian Lin
BACKGROUND: Astragalus was broadly used for treating heart failure (HF) and arrhythmias in East Asia for thousands of years. Astragalus granule (AG), extracted from Astragalus, shows beneficial effect on the treatment of HF in clinical research. We hypothesized that administration of AG prevents the remodeling of L-type Ca(2+) current (ICa-L) in HF mice by the downregulation of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). METHODS: HF mice were induced by thoracic aortic constriction (TAC)...
2017: Evidence-based Complementary and Alternative Medicine: ECAM
https://www.readbyqxmd.com/read/28852171/integrative-approach-with-electrophysiological-and-theoretical-methods-reveals-a-new-role-of-s4-positively-charged-residues-in-pkd2l1-channel-voltage-sensing
#9
Tomohiro Numata, Kunichika Tsumoto, Kazunori Yamada, Tatsuki Kurokawa, Shinichi Hirose, Hideki Nomura, Mitsuhiro Kawano, Yoshihisa Kurachi, Ryuji Inoue, Yasuo Mori
Numerical model-based simulations provide important insights into ion channel gating when experimental limitations exist. Here, a novel strategy combining numerical simulations with patch clamp experiments was used to investigate the net positive charges in the putative transmembrane segment 4 (S4) of the atypical, positively-shifted voltage-dependence of polycystic kidney disease 2-like 1 (PKD2L1) channel. Charge-neutralising mutations (K452Q, K455Q and K461Q) in S4 reduced gating charges, positively shifted the Boltzmann-type activation curve [i...
August 29, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28810912/inhibition-of-trpm7-suppresses-cell-proliferation-of-colon-adenocarcinoma-in-vitro-and-induces-hypomagnesemia-in-vivo-without-affecting-azoxymethane-induced-early-colon-cancer-in-mice
#10
Junhao Huang, Hideki Furuya, Malika Faouzi, Zheng Zhang, Mahealani Monteilh-Zoller, Kelly Galbraith Kawabata, F David Horgen, Toshihiko Kawamori, Reinhold Penner, Andrea Fleig
BACKGROUND: Magnesium (Mg(2+)) is an essential cation implicated in carcinogenesis, solid tumor progression and metastatic potential. The Transient Receptor Potential Melastatin Member 7 (TRPM7) is a divalent ion channel involved in cellular and systemic Mg(2+) homeostasis. Abnormal expression of TRPM7 is found in numerous cancers, including colon, implicating TRPM7 in this process. METHODS: To establish a possible link between systemic magnesium (Mg(2+)) status, the Mg(2+) conducting channel TRPM7 in colon epithelial cells, and colon carcinogenesis, in vitro whole-cell patch clamp electrophysiology, qPCR, and pharmacological tools were used probing human colorectal adenocarcinoma HT-29 as well as normal primary mouse colon epithelial cells...
August 15, 2017: Cell Communication and Signaling: CCS
https://www.readbyqxmd.com/read/28758259/transient-receptor-potential-melastatin-4-channel-is-required-for-rat-dental-pulp-stem-cell-proliferation-and-survival
#11
T D Ngoc Tran, K E Stovall, T Suantawee, Y Hu, S Yao, L-J Yang, S Adisakwattana, H Cheng
OBJECTIVES: Investigate the role of the transient receptor potential melastatin 4 (TRPM4) channel in rat dental pulp stem cell (DPSC) proliferation and survival. MATERIALS AND METHODS: Immunofluorescence and FACS analysis were used to detect the stem cell marker CD90. Alizarin Red S and Oil Red O staining were used to identify osteoblast and adipocyte differentiation, respectively. To characterize TRPM4, patch-clamp recordings were obtained from single cells in the whole-cell configuration mode...
October 2017: Cell Proliferation
https://www.readbyqxmd.com/read/28754781/nongenomic-modulation-of-the-large-conductance-voltage-and-ca-2-activated-k-channels-by-estrogen-a-novel-regulatory-mechanism-in-human-detrusor-smooth-muscle
#12
Kiril L Hristov, Shankar P Parajuli, Aaron Provence, Eric S Rovner, Georgi V Petkov
Estrogens have an important role in regulating detrusor smooth muscle (DSM) function. However, the underlying molecular and cellular mechanisms by which estrogens control human DSM excitability and contractility are not well known. Here, we used human DSM specimens from open bladder surgeries on 27 patients to elucidate the mechanism by which 17β-estradiol regulates large conductance voltage- and Ca(2+)-activated K(+) (BK) channels, the most prominent K(+) channels in human DSM We employed single BK channel recordings on inside-out excised membrane patches, perforated whole-cell patch-clamp on freshly isolated DSM cells, and isometric tension recordings on DSM-isolated strips to investigate the mechanism by which 17β-estradiol activates BK channels...
July 2017: Physiological Reports
https://www.readbyqxmd.com/read/28744649/electrophysiological-features-of-single-store-operated-calcium-channels-in-hek-s4-cell-line-with-stable-stim1-protein-knockdown
#13
A V Shalygin, V A Vigont, L N Glushankova, O A Zimina, D O Kolesnikov, A Yu Skopin, E V Kaznacheeva
An important role in intracellular calcium signaling is played by store-operated channels activated by STIM proteins, calcium sensors of the endoplasmic reticulum. In stable STIM1 knockdown HEK S4 cells, single channels activated by depletion of intracellular calcium stores were detected by cell-attached patch-clamp technique and their electrophysiological parameters were described. Comparison of the properties of single channels in HEK293 and HEK S4 cells revealed no significant differences in their current-voltage curves, while regulation of store-operated calcium channels in these cell lines depended on the level of STIM1 expression...
July 26, 2017: Bulletin of Experimental Biology and Medicine
https://www.readbyqxmd.com/read/28711067/pa-6-inhibits-inward-rectifier-currents-carried-by-v93i-and-d172n-gain-of-function-kir2-1-channels-but-increases-channel-protein-expression
#14
Yuan Ji, Marlieke G Veldhuis, Jantien Zandvoort, Fee L Romunde, Marien J C Houtman, Karen Duran, Gijs van Haaften, Eva-Maria Zangerl-Plessl, Hiroki Takanari, Anna Stary-Weinzinger, Marcel A G van der Heyden
BACKGROUND: The inward rectifier potassium current IK1 contributes to a stable resting membrane potential and phase 3 repolarization of the cardiac action potential. KCNJ2 gain-of-function mutations V93I and D172N associate with increased IK1, short QT syndrome type 3 and congenital atrial fibrillation. Pentamidine-Analogue 6 (PA-6) is an efficient (IC50 = 14 nM with inside-out patch clamp methodology) and specific IK1 inhibitor that interacts with the cytoplasmic pore region of the KIR2...
July 15, 2017: Journal of Biomedical Science
https://www.readbyqxmd.com/read/28700658/nanosecond-electric-pulses-differentially-affect-inward-and-outward-currents-in-patch-clamped-adrenal-chromaffin-cells
#15
Lisha Yang, Gale L Craviso, P Thomas Vernier, Indira Chatterjee, Normand Leblanc
This study examined the effect of 5 ns electric pulses on macroscopic ionic currents in whole-cell voltage-clamped adrenal chromaffin cells. Current-voltage (I-V) relationships first established that the early peak inward current was primarily composed of a fast voltage-dependent Na+ current (INa), whereas the late outward current was composed of at least three ionic currents: a voltage-gated Ca2+ current (ICa), a Ca2+-activated K+ current (IK(Ca)), and a sustained voltage-dependent delayed rectifier K+ current (IKV)...
2017: PloS One
https://www.readbyqxmd.com/read/28655649/interregional-electro-mechanical-heterogeneity-in-the-rabbit-myocardium
#16
REVIEW
Franz F Dressler, Ilona Bodi, Marius Menza, Robin Moss, Heiko Bugger, Christoph Bode, Jan C Behrends, Gunnar Seemann, Katja E Odening
BACKGROUND: Increased electrical heterogeneity has been causatively linked to arrhythmic disorders, yet the knowledge about physiological heterogeneity remains incomplete. This study investigates regional electro-mechanical heterogeneities in rabbits, one of the key animal models for arrhythmic disorders. METHODS AND FINDINGS: 7 wild-type rabbits were examined by phase-contrast magnetic resonance imaging in vivo to assess cardiac wall movement velocities. Using a novel data-processing algorithm regional contraction-like profiles were calculated...
June 24, 2017: Progress in Biophysics and Molecular Biology
https://www.readbyqxmd.com/read/28638923/-reconstitution-of-large-conductance-calcium-activated-potassium-channels-into-artificial-planar-lipid-bilayers
#17
Jun Cheng, Xiao-Rong Zeng, Xiao-Qiu Tan, Peng-Yun Li, Jing Wen, Liang Mao, Yan Yang
This study was aimed to establish a method to create a stable planar lipid bilayer membranes (PLBMs), in which large conductance calcium-activated potassium channels (BKCa) were reconstituted. Using spreading method, PLBMs were prepared by decane lipid fluid consisting of N2-weathered mixture of phosphatidylcholine and cholesterol at 3:1 ratio. After successful incorporation of BKCa channel into PLBMs, single channel characteristics of BKCa were studied by patch clamp method. The results showed that i) the single channel conductance of BKCa was (206...
June 25, 2017: Sheng Li Xue Bao: [Acta Physiologica Sinica]
https://www.readbyqxmd.com/read/28631948/possible-contribution-of-pannexin-1-to-capsaicin-induced-atp-release-in-rat-nasal-columnar-epithelial-cells
#18
Toyoaki Ohbuchi, Ba Hung Do, Hiroki Koizumi, Shoko Takeuchi, Yoichi Ueta, Hideaki Suzuki
Current evidence indicates that transient receptor potential (TRP) channel activity involves a relationship between opening of pannexin-1 and release of ATP into the extracellular space. We examined the effects of agonists of thermosensitive TRP channels (TRPM8, TRPA1, TRPV1, and TRPV2) on ATP release from rat nasal mucosa, and measured ciliary beat frequency (CBF) using digital high-speed video imaging. Single-cell patch clamping from dissociated rat nasal columnar epithelial cells was performed to confirm the relationship between pannexin-1 and TRP...
July 4, 2017: Channels
https://www.readbyqxmd.com/read/28622417/the-anti-migraine-component-of-butterbur-extracts-isopetasin-desensitizes-peptidergic-nociceptors-by-acting-on-trpa1-cation-channel
#19
Silvia Benemei, Francesco De Logu, Simone Li Puma, Ilaria Maddalena Marone, Elisabetta Coppi, Filippo Ugolini, Wolfgang Liedtke, Federica Pollastro, Giovanni Appendino, Pierangelo Geppetti, Serena Materazzi, Romina Nassini
BACKGROUND AND PURPOSE: The mechanism of the anti-migraine action of extracts of butterbur [Petasites hybridus (L.) Gaertn.] is unknown. Here, we investigated the ability of isopetasin, a major constituent of these extracts, to specifically target TRPA1 channel and to affect functional responses relevant to migraine. EXPERIMENTAL APPROACH: Single-cell calcium imaging and patch-clamp recordings in human and rodent TRPA1-expressing cells, neurogenic motor responses in rodent isolated urinary bladder, release of CGRP from mouse spinal cord in vitro and facial rubbing in mice and meningeal blood flow in rats were examined...
September 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28616863/contrasting-effects-of-phosphatidylinositol-4-5-bisphosphate-on-cloned-tmem16a-and-tmem16b-channels
#20
Chau M Ta, Kathryn E Acheson, Nils J G Rorsman, Remco C Jongkind, Paolo Tammaro
BACKGROUND AND PURPOSE: Ca(2+) -activated Cl(-) channels (CaCCs) are gated open by a rise in intracellular Ca(2+) concentration ([Ca(2+) ]i ), typically provoked by activation of Gq -protein coupled receptors (Gq PCR). Gq PCR activation initiates depletion of plasmalemmal phosphatidylinositol 4,5-bisphosphate (PIP2 ). Here, we determined whether PIP2 acts as a signalling lipid for CaCCs coded by the TMEM16A and TMEM16B genes. EXPERIMENTAL APPROACH: Patch-clamp electrophysiology, in conjunction with genetically encoded systems to control cellular PIP2 content, was used to define the mechanism of action of PIP2 on TMEM16A and TMEM16B channels...
September 2017: British Journal of Pharmacology
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