Electrophysiological characterization of sodium‐activated potassium channels in <scp>NG</scp>108‐15 and <scp>NSC</scp>‐34 motor neuron‐like cells

Wu, Sheng‐Nan; Yeh, Chia Chen; Huang, Hsien Ching; So, Edmund Cheung; Lo, Yi-Ching

doi:10.1111/j.1748-1716.2012.02438.x

Cited by 21 publications

(20 citation statements)

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“…Δ G 0 for I K(DR) activation at 0 mV with or without treatment of SGX would be equal to q × F × V 1/2 [25, 26]. The standard errors of Δ G 0 (i.e., ) were calculated according to:where σ q and represent the standard errors in q and V 1/2 respectively.…”

Section: Methodsmentioning

confidence: 99%

Important modifications by sugammadex, a modified γ-cyclodextrin, of ion currents in differentiated NSC-34 neuronal cells

Hsu

Huang

et al. 2017

BMC Neurosci

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BackgroundSugammadex (SGX) is a modified γ-cyclodextrin used for reversal of steroidal neuromuscular blocking agents during general anesthesia. Despite its application in clinical use, whether SGX treatment exerts any effects on membrane ion currents in neurons remains largely unclear. In this study, effects of SGX treatment on ion currents, particularly on delayed-rectifier K+ current [I K(DR)], were extensively investigated in differentiated NSC-34 neuronal cells.ResultsAfter cells were exposed to SGX (30 μM), there was a reduction in the amplitude of I K(DR) followed by an apparent slowing in current activation in response to membrane depolarization. The challenge of cells with SGX produced a depolarized shift by 15 mV in the activation curve of I K(DR) accompanied by increased gating charge of this current. However, the inactivation curve of I K(DR) remained unchanged following SGX treatment, as compared with that in untreated cells. According to a minimal reaction scheme, the lengthening of activation time constant of I K(DR) caused by cell treatment with different SGX concentrations was quantitatively estimated with a dissociation constant of 17.5 μM, a value that is clinically achievable. Accumulative slowing in I K(DR) activation elicited by repetitive stimuli was enhanced in SGX-treated cells. SGX treatment did not alter the amplitude of voltage-gated Na+ currents. In SGX-treated cells, dexamethasone (30 μM), a synthetic glucocorticoid, produced little or no effect on L-type Ca2+ currents, although it effectively suppressed the amplitude of this current in untreated cells.ConclusionsThe treatment of SGX may influence the amplitude and gating of I K(DR) and its actions could potentially contribute to functional activities of motor neurons if similar results were found in vivo.Electronic supplementary materialThe online version of this article (doi:10.1186/s12868-016-0320-5) contains supplementary material, which is available to authorized users.

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Section: Methodsmentioning

confidence: 99%

Important modifications by sugammadex, a modified γ-cyclodextrin, of ion currents in differentiated NSC-34 neuronal cells

Hsu

Huang

et al. 2017

BMC Neurosci

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“…However, in our study, neither tetrodotoxin, ranolazine nor riluzole was demonstrated to have any effects on PALCAR-stimulated I MEP in GH 3 cells. Those compounds are recognized to suppress the amplitude of late Na + currents [32,33]. PALCAR produced a progressive increase of I MEP in GH 3 cells with an EC 50 value of 2.4 µM.…”

Section: Discussionmentioning

confidence: 99%

Identification of Minuscule Inward Currents as Precursors to Membrane Electroporation-Induced Currents: Real-Time Prediction of Pore Appearance

Tsai

et al. 2013

Cell Physiol Biochem

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Background/Aims: The objective of this study is to examine the current signals in response to large hyperpolarizations with the aid of principal component analysis (PCA) to search for or even predict current fluctuations related to membrane electroporation-induced current (I_MEP). Methods: The characteristics of principal eigenvalues generated for I_MEP and the current signals at 10 sec prior to the start of initial I_MEP (I_Pre) were examined. As membrane hyperpolarizations were applied at 0.1 Hz, the appearance of I_MEP coincided with the higher principal eigenvalues extracted in PCA. Results: Subsequent addition of LaCl₃ (100 µM) greatly reduced I_MEP and associated principal eigenvalues. In real-time analysis for a single frame (i.e, 300 msec), in response to large hyperpolarization, multiple runs of heralded minuscule inward currents (I_min) occurring before large rise in current amplitudes were detected. With PCA, such heralded I_min was noted to coincide with the extreme principal eigenvalues. The duration of I_min together with large principal eigenvalues was influenced by different levels of membrane hyperpolarization. In GH3 cells, palmitoyl-L-carnitine (PALCAR), a long-chain acylcarnitine, effectively increased the I_MEP amplitude with an EC₅₀ value of 2.4 µM. However, in PALCAR-treated cells, the I_min together with higher principal eigenvalues disappeared, while in isoflurane-treated cells, I_min occurring before large rise of current amplitude remained intact. Similarly, the PCA analysis from I_Pre in RAW 264.6 macrophages showed the presence of herald I_min accompanied by the extreme principal eigenvalues. Conclusion: It is clear from this study that these large principal eigenvalues are representative of MEP-associated formation of electropores. Therefore, different compositions around the surface membrane of cells may alter the appearance of I_min followed by I_MEP emergence.

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“…In a separate set of experiments, the pipette was filled with the solution which contained chlorotoxin (1 µM). By use of F-250 fluorescence spectrophotometer and the ratiometric fura-2 measurement, the free Ca 2+ concentration for high K + -bathing solution was 208±17 nM (n=7 Cell preparation and differentiation NSC-34 neuronal cells were originally produced by fusion of the motor neuron-enriched, embryonic mouse spinal cords with the mouse neuroblastoma [14,21]. These cells were kindly provided by Professor Dr. Yuh-Jyh Jong (Department of Pediatrics, Kaohsiung Medical University Hospital, Kaohsiung City, Taiwan).…”

Section: Drugs and Solutionsmentioning

confidence: 99%

“…An anti-vibration air table was used to enhance stability during electrophysiological recordings. Patchclamp recordings were obtained in cell-attached, inside-out, or whole-cell configuration using either an RK-400 (Biol-Logic, Claix, France) or Axopatch 200B (Molecular Devices, Sunnyvale, CA) amplifier [21,22]. The junctional potentials between the pipette solution and extracellular medium were corrected immediately before seal formation was made.…”

Section: Electrophysiological Measurementsmentioning

confidence: 99%

Evidence of Decreased Activity in Intermediate-Conductance Calcium-Activated Potassium Channels During Retinoic Acid–Induced Differentiation in Motor Neuron–Like NSC-34 Cells

Chen

Ruan

2018

Cell Physiol Biochem

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Background/Aims: Intermediate-conductance Ca²⁺-activated K⁺ (IK_Ca; K_Ca3.1 or KCNN4) channels affect the behaviors of central neurons including motor neurons. The mechanism through which neuronal differentiation is related to the activity of these channels remains largely unclear. Methods: By using various molecular biology tools and electrophysiological measurements, we investigated possible changes in the activity of IK_Ca channels in a retinoic acid (RA)-induced differentiation process in motor neuron-like NSC-34 cells. Results: The protein and messenger RNA expression of K_Ca3.1 substantially diminished as NSC-34 cells were differentiated with low serum (1%) and 1 µM RA. In whole-cell current recordings, the density of delayed-rectifier K⁺ currents obtained from differentiated cells was elevated. However, the density of a ramp pulse-elicited K⁺ current that was sensitive to blockage by 1-((2-chlorophenyl) (diphenyl)methyl)-1H-pyrazole (TRAM-34)—an inhibitor of IK_Ca channels—was significantly higher in undifferentiated NSC-34 cells than in differentiated cells. In undifferentiated cells, the activity of IK_Ca channels was readily detected and the probability of channel openings was resistant to stimulation by diazoxide or suppression by verruculogen. Furthermore, this probability was increased by 5,6-dichloro-1-ethyl-1,3-dihydro-2H-benzimidazol-2-one or 9-phenanthrol and reduced by TRAM-34. The channel-opening probability decreased in RA-induced differentiated cells, whereas the single-channel conductance of IK_Ca channels did not differ between undifferentiated and differentiated cells. Moreover, the slow component of the mean closed time in these channels was significantly shorter in undifferentiated cells than in differentiated cells; however, the mean open time in the channel remained unchanged as cells were differentiated. Conclusion: RA-induced differentiation in neurons could exert a suppressive effect on the activity of IK_Ca channels.

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Electrophysiological characterization of sodium‐activated potassium channels in NG108‐15 and NSC‐34 motor neuron‐like cells

Abstract: There is a direct association of Na(+) and K(Na) channels which can provide the rapid activation of K(Na) channels required to regulate AP firing occurring in motor neurons.

Cited by 21 publications

References 39 publications

Important modifications by sugammadex, a modified γ-cyclodextrin, of ion currents in differentiated NSC-34 neuronal cells

Important modifications by sugammadex, a modified γ-cyclodextrin, of ion currents in differentiated NSC-34 neuronal cells

Identification of Minuscule Inward Currents as Precursors to Membrane Electroporation-Induced Currents: Real-Time Prediction of Pore Appearance

Evidence of Decreased Activity in Intermediate-Conductance Calcium-Activated Potassium Channels During Retinoic Acid–Induced Differentiation in Motor Neuron–Like NSC-34 Cells

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