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Single channel patch clamp

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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
#1
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
#2
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
#3
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
#4
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
#5
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...
February 10, 2017: Channels
https://www.readbyqxmd.com/read/28622417/the-antimigraine-butterbur-ingredient-isopetasin-desensitises-peptidergic-nociceptors-via-the-transient-receptor-potential-ankyrin-1-channel
#6
Silvia Benemei, Francesco De Logu, Simone Li Puma, Ilaria Maddalena Marone, Elisabetta Coppi, Filippo Ugolini, Wolfgang Liedtke, Pollastro Federica, Giovanni Appendino, Pierangelo Geppetti, Serena Materazzi, Romina Nassini
BACKGROUND AND PURPOSE: The mechanism of the antimigraine action of butterbur [Petasites hybridus (L.) Gaertn.] is unknown. Here, we investigated the ability of isopetasin, a major butterbur constituent, to specifically target the transient receptor ankyrin 1 (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 isolated rat/mouse urinary bladder, release of calcitonin gene-related peptide (CGRP) from mouse spinal cord in vitro, and facial rubbing in mice and meningeal blood flow in rat were examined...
June 16, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28616863/contrasting-effects-of-phosphatidylinositol-4-5-bisphosphate-pip2-on-cloned-tmem16a-and-tmem16b-channels
#7
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 Gq -protein coupled receptor activation (Gq PCR). Gq PCR activation initiates depletion of plasmalemmal phosphatidylinositol 4,5-bisphosphate (PIP2 ). Here we ask 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...
June 14, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28612138/transient-receptor-potential-vanilloid-4-trpv4-channel-as-a-target-of-crotamiton-and-its-bimodal-effects
#8
Hiroki Kittaka, Yu Yamanoi, Makoto Tominaga
The sensation of itching can be defined as "an unpleasant cutaneous sensation that provokes a desire to scratch." The perception of itching is not critical for the maintenance of life, but persistent itching can be extremely irritating and decreases the quality of life. Crotamiton (N-ethyl-o-crotonotoluidide) has been used as an anti-itch agent for humans for around 70 years. In spite of the long use of crotamiton, its mechanism of action remains unknown. We hypothesized that crotamiton might have effects on transient receptor potential (TRP) channels expressed in the peripheral nervous system and the skin...
June 13, 2017: Pflügers Archiv: European Journal of Physiology
https://www.readbyqxmd.com/read/28583845/cav1-2-channel-current-block-by-the-pka-inhibitor-h-89-in-rat-tail-artery-myocytes-via-a-pka-independent-mechanism-electrophysiological-functional-and-molecular-docking-studies
#9
Fabio Fusi, Alfonso Trezza, Ottavia Spiga, Giampietro Sgaragli, Sergio Bova
To characterize the role of cAMP-dependent protein kinase (PKA) in regulating vascular Ca(2+) current through Cav1.2 channels [ICa1.2], we have documented a marked capacity of the isoquinoline H-89, widely used as a PKA inhibitor, to reduce current amplitude. We hypothesized that the ICa1.2 inhibitory activity of H-89 was mediated by mechanisms unrelated to PKA inhibition. To support this, an in-depth analysis of H-89 vascular effects on both ICa1.2 and contractility was undertaken by performing whole-cell patch-clamp recordings and functional experiments in rat tail main artery single myocytes and rings, respectively...
June 2, 2017: Biochemical Pharmacology
https://www.readbyqxmd.com/read/28573491/p2x7-receptor-large-pore-signaling-in-avian-m%C3%A3-ller-glial-cells
#10
Robson X Faria, Hercules R Freitas, Ricardo A M Reis
ATP is a pleiotropic molecule that promotes extra- and intracellular signaling to regulate numerous functions. This nucleotide activates purine and pyrimidine receptors at the plasma membrane, categorized as ionotropic P2X or G-protein-coupled receptor (GPCR) P2Y receptors. P2X are ligand-gated ion channel receptors, expressed in both retinal neurons and Müller cells leading to neuron-glia communication, calcium waves and neurovascular coupling. However, how P2X pore is formed upon ATP activation and how signaling pathways regulates the complex is still a matter of controversy...
June 1, 2017: Journal of Bioenergetics and Biomembranes
https://www.readbyqxmd.com/read/28570546/electrophysiological-analysis-of-human-pluripotent-stem-cell-derived-cardiomyocytes-hpsc-cms-using-multi-electrode-arrays-meas
#11
Luca Sala, Dorien Ward-van Oostwaard, Leon G J Tertoolen, Christine L Mummery, Milena Bellin
Cardiomyocytes can now be derived with high efficiency from both human embryonic and human induced-Pluripotent Stem Cells (hPSC). hPSC-derived cardiomyocytes (hPSC-CMs) are increasingly recognized as having great value for modeling cardiovascular diseases in humans, especially arrhythmia syndromes. They have also demonstrated relevance as in vitro systems for predicting drug responses, which makes them potentially useful for drug-screening and discovery, safety pharmacology and perhaps eventually for personalized medicine...
May 12, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28569571/curcumin-inhibits-oxidative-stress-induced-trpm2-channel-activation-calcium-ion-entry-and-apoptosis-values-in-sh-sy5y-neuroblastoma-cells-involvement-of-transfection-procedure
#12
Ahmi Öz, Ömer Çelik
Transient Receptor Potential (TRP) channels are mostly Ca(2+) permeable cation channels. Transient Receptor Potential Melastatin-like 2 (TRPM2) is expressed in neurological tissues such as brain, dorsal root ganglia (DRG) neurons, hippocampus and also liver, heart and kidney. The SH-SY5Y cells are mostly used as a cellular model of neurodegenerative diseases, Alzheimer's and Parkinson's diseases. Curcumin, shows phenolic structure, synthesized by Curcuma longa L. (turmeric), has powerful non-enzymatically antioxidant effects compared with Vitamin E...
June 1, 2017: Molecular Membrane Biology
https://www.readbyqxmd.com/read/28555110/reduced-membrane-insertion-of-clc-k-by-v33l-barttin-results-in-loss-of-hearing-but-leaves-kidney-function-intact
#13
Hua Tan, Stefanie Bungert-Plümke, Christoph Fahlke, Gabriel Stölting
In the mammalian ear, transduction of sound stimuli is initiated by K(+) entry through mechano-sensitive channels into inner hair cells. K(+) entry is driven by a positive endocochlear potential that is maintained by the marginal cell layer of the stria vascularis. This process requires basolateral K(+) import by NKCC1 Na(+)-2Cl(-)-K(+) co-transporters as well as Cl(-) efflux through ClC-Ka/barttin or ClC-Kb/barttin channels. Multiple mutations in the gene encoding the obligatory CLC-K subunit barttin, BSND, have been identified in patients with Bartter syndrome type IV...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28511915/altered-ionic-currents-and-amelioration-by-igf-1-and-pacap-in-motoneuron-derived-cells-modelling-sbma
#14
Aura M Jiménez Garduño, Leon J Juárez-Hernández, María J Polanco, Laura Tosatto, Daniela Michelatti, Daniele Arosio, Manuela Basso, Maria Pennuto, Carlo Musio
Spinal and bulbar muscular atrophy (SBMA), also known as Kennedy's disease, is a motor neuron disease caused by the expansion of a polymorphic CAG tandem repeat encoding a polyglutamine (polyQ) tract in the androgen receptor (AR) gene. SBMA is triggered by the binding of mutant AR to its natural ligands, testosterone and dihydrotestosterone (DHT). To investigate the neuronal alterations of motor neuron cell models of SBMA, we applied patch-clamp methods to verify how polyQ expansions in the AR alter cell ionic currents...
May 10, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28495885/proteolytic-cleavage-of-the-hydrophobic-domain-in-the-cav%C3%AE-2%C3%AE-1-subunit-improves-assembly-and-activity-of-cardiac-cav1-2-channels
#15
Emilie Segura, Benoîte Bourdin, Marie-Philippe Tétreault, Julie Briot, Bruce G Allen, Gaétan Mayer, Lucie Parent
Voltage-gated L-type CaV1.2 channels in cardiomyocytes exist as heteromeric complexes with the pore-forming CaVα1, CaVβ, and CaVα2δ1 subunits. The full complement of subunits is required to reconstitute the native-like properties of L-type Ca(2+) currents, but the molecular determinants responsible for the formation of the heteromeric complex are still being studied. Enzymatic treatment with phosphatidylinositol-specific phospholipase C, a phospholipase C specific for the cleavage of glycosylphosphatidylinositol (GPI)-anchored proteins, disrupted plasma membrane localization of the cardiac CaVα2δ1 prompting us to investigate deletions of its hydrophobic transmembrane domain...
June 30, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28483800/xe991-and-linopirdine-are-state-dependent-inhibitors-for-kv7-kcnq-channels-that-favor-activated-single-subunits
#16
Derek L Greene, Seungwoo Kang, Naoto Hoshi
M-channel inhibitors, especially XE991, are being used increasingly in animal experiments; however, insufficient characterization of XE991 at times confounds the interpretation of results when using this compound. Here, we demonstrate that XE991 and linopirdine are state-dependent inhibitors that favor the activated-subunit of neuronal Kv7/KCNQ channels. We performed patch-clamp experiments on homomeric Kv7.2 or heteromeric Kv7.2/3 channels expressed in Chinese hamster ovary cells to characterize XE991 and linopirdine...
July 2017: Journal of Pharmacology and Experimental Therapeutics
https://www.readbyqxmd.com/read/28483598/the-mechano-sensitivity-of-cardiac-atp-sensitive-potassium-channels-is-mediated-by-intrinsic-mgatpase-activity
#17
Mohammad Fatehi, Christian C Carter, Nermeen Youssef, Peter E Light
Cardiac ATP-sensitive K(+) (KATP) channel activity plays an important cardio-protective role in regulating excitability in response to metabolic stress. Evidence suggests that these channels are also mechano-sensitive and therefore may couple KATP channel activity to increased cardiac workloads. However, the molecular mechanism that couples membrane stretch to channel activity is not currently known. We hypothesized that membrane stretch may alter the intrinsic MgATPase activity of the cardiac KATP channel resulting in increased channel activation...
May 5, 2017: Journal of Molecular and Cellular Cardiology
https://www.readbyqxmd.com/read/28472069/detection-of-trpv4-channel-current-like-activity-in-fawn-hooded-hypertensive-fhh-rat-cerebral-arterial-muscle-cells
#18
Debebe Gebremedhin, David X Zhang, Dorothee Weihrauch, Nnamdi N Uche, David R Harder
The transient receptor potential vallinoid type 4 (TRPV4) is a calcium entry channel known to modulate vascular function by mediating endothelium-dependent vasodilation. The present study investigated if isolated cerebral arterial myocytes of the Fawn Hooded hypertensive (FHH) rat, known to display exaggerated KCa channel current activity and impaired myogenic tone, express TRPV4 channels at the transcript and protein level and exhibit TRPV4-like single-channel cationic current activity. Reverse transcription polymerase chain reaction (RT-PCR), Western blot, and immunostaining analysis detected the expression of mRNA transcript and translated protein of TRPV4 channel in FHH rat cerebral arterial myocytes...
2017: PloS One
https://www.readbyqxmd.com/read/28468944/enac-activity-is-regulated-by-calpain-2-proteolysis-of-marcks-proteins
#19
Darrice S Montgomery, Ling Yu, Zinah M Ghazi, Tiffany L Thai, Otor Al-Khalili, He-Ping Ma, Douglas C Eaton, Abdel A Alli
We previously demonstrated a role for the myristoylated alanine-rich C kinase substrate (MARCKS) to serve as an adaptor protein in the anionic phospholipid phosphate-dependent regulation of the epithelial sodium channel (ENaC). Both MARCKS and ENaC are regulated by proteolysis. Calpains are a family of ubiquitously expressed intracellular Ca(2+)-dependent cysteine proteases involved in signal transduction. Here we examine the role of calpain-2 in regulating MARCKS and ENaC in cultured renal epithelial cells and in the mouse kidney...
July 1, 2017: American Journal of Physiology. Cell Physiology
https://www.readbyqxmd.com/read/28436159/modulation-of-late-sodium-current-by-ca-2-calmodulin-dependent-protein-kinase-ii-protein-kinase-c-and-ca-2-during-hypoxia-in-rabbit-ventricular-myocytes
#20
Chen Fu, Jie Hao, Mengliu Zeng, Yejia Song, Wanzhen Jiang, Peihua Zhang, Antao Luo, Zhenzhen Cao, Luiz Belardinelli, Jihua Ma
What is the central question of this study? Hypoxia-induced increase in late sodium current (INa,L ) is associated with conditions causing cellular Ca(2+) overload and contributes to arrhythmogenesis in the ventricular myocardium. The INa,L is an important drug target. We investigated intracellular signal transduction pathways involved in modulation of INa,L during hypoxia. What is the main finding and its importance? Hypoxia caused increases in INa,L , reverse Na(+) -Ca(2+) exchange current and diastolic [Ca(2+) ], which were attenuated by inhibitors of Ca(2+) -calmodulin-dependent protein kinase II (CaMKII) and protein kinase C and by a Ca(2+) chelator...
July 1, 2017: Experimental Physiology
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