Fully activated potassium current-voltage relationship in the Ranvier node

1980 ◽  
Vol 384 (1) ◽  
pp. 49-56 ◽  
Author(s):  
David Attwell ◽  
Jean-Marc Dubois ◽  
Carlos Ojeda
Keyword(s):  
Potassium Current ◽  
Ranvier Node ◽  
Current Voltage ◽  
Current Voltage Relationship ◽  
Voltage Relationship

Human fetal central neurons in culture: voltage- and ligand-gated currents

1995 ◽  
Vol 74 (5) ◽  
pp. 1889-1899 ◽  
Author(s):  
D. W. Sah
Keyword(s):  
Current Density ◽  
Potassium Current ◽  
Time Course ◽  
Voltage Dependence ◽  
Sodium Current ◽  
Sodium Currents ◽  
Current Voltage ◽  
Channel Currents ◽  
Current Voltage Relationship ◽  
Voltage Relationship

1. The functional properties of sodium, potassium, calcium, N-methyl-D-aspartate (NMDA), kainate, and gamma-aminobutyric acid (GABA) currents were studied in dissociated monolayer cultures of fetal human brain neurons, using the whole cell patch-clamp technique. 2. Sodium currents were characterized with respect to the following properties: current density, voltage dependence of activation, voltage dependence of inactivation, and sensitivity to tetrodotoxin (TTX). All sodium currents exhibited voltage dependencies of activation and inactivation, and sensitivities to TTX that are characteristic of the neuronal form of the sodium current. 3. At least two types of potassium current were present, resembling the delayed rectifier and fast-inactivating potassium current. These two types of potassium current were distinguishable by their different kinetics, voltage dependencies of activation and inactivation, and sensitivities to 4-aminopyridine and tetraethylammonium. 4. High-voltage-activated calcium channel currents were present and were characterized with respect to current density, voltage dependencies of activation and inactivation, and sensitivity to cadmium. Low-voltage-activated calcium channel currents were also present. 5. NMDA- and kainate-gated currents were studied with respect to current density, time course, and current-voltage relationship. Kainate currents were also characterized with respect to inhibition by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). In addition, NMDA and kainate responses were compared for cortical versus cerebellar neurons. NMDA responses, which are only found in neurons, were present, confirming the neuronal phenotype suggested by the presence of the neuronal form of the sodium current. Nondesensitizing kainate currents were also present, with a half-maximally effective concentration (EC50) of approximately 200 microM for kainate; CNQX inhibited the kainate current with a half-inactivating concentration of 0.55 microM. 6. GABA-gated currents were characterized with respect to current density, time course, receptor subtype, desensitization, dose response, current-voltage relationship, ionic selectivity, pharmacology, and potentiation by the neurosteroid 5 alpha-pregnan-3 alpha-ol-11,20-dione (alfaxalone). Desensitizing GABAA currents were selective for chloride, inhibited by bicuculline and tert-butyl-bicyclophosphorothionate, and potentiated by diazepam, pentobarbital sodium, and alfaxalone. The EC50 for GABA was 15 microM.

scholarly journals Plasticity of calcium-permeable AMPA glutamate receptors in Pro-opiomelanocortin neurons

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Shigetomo Suyama ◽  
Alexandra Ralevski ◽  
Zhong-Wu Liu ◽  
Marcelo O Dietrich ◽  
Toshihiko Yada ◽  
...  
Keyword(s):  
Food Deprivation ◽  
High Fat Diet ◽  
Receptor Complex ◽  
High Fat ◽  
Fasted State ◽  
Linear Current ◽  
Current Voltage ◽  
Relationship Of ◽  
Current Voltage Relationship ◽  
Voltage Relationship

POMC neurons integrate metabolic signals from the periphery. Here, we show in mice that food deprivation induces a linear current-voltage relationship of AMPAR-mediated excitatory postsynaptic currents (EPSCs) in POMC neurons. Inhibition of EPSCs by IEM-1460, an antagonist of calcium-permeable (Cp) AMPARs, diminished EPSC amplitude in the fed but not in the fasted state, suggesting entry of GluR2 subunits into the AMPA receptor complex during food deprivation. Accordingly, removal of extracellular calcium from ACSF decreased the amplitude of mEPSCs in the fed but not the fasted state. Ten days of high-fat diet exposure, which was accompanied by elevated leptin levels and increased POMC neuronal activity, resulted in increased expression of Cp-AMPARs on POMC neurons. Altogether, our results show that entry of calcium via Cp-AMPARs is inherent to activation of POMC neurons, which may underlie a vulnerability of these neurons to calcium overload while activated in a sustained manner during over-nutrition.

Capsaicin and nicotine both activate a subset of rat trigeminal ganglion neurons

1996 ◽  
Vol 270 (6) ◽  
pp. C1807-C1814 ◽  
Author(s):  
L. Liu ◽  
S. A. Simon
Keyword(s):  
Trigeminal Ganglion ◽  
Acetylcholine Receptors ◽  
Ganglion Cells ◽  
Whole Cell Patch Clamp ◽  
Current Voltage ◽  
Trigeminal Ganglion Neurons ◽  
Ganglion Neurons ◽  
Relationship Of ◽  
Current Voltage Relationship ◽  
Voltage Relationship

Nicotine and capsaicin produce many similar physiological responses that include pain, irritation, and vasodilation. To determine whether neuronal nicotine acetylcholine receptors (nAChR) are present on capsaicin-sensitive neurons, whole cell patch-clamp recordings were performed on rat trigeminal ganglion cells. It was found that approximately 20% of the total number of neurons tested was activated by both 100 microM nicotine and 1 nM capsaicin. Other subsets of neurons were activated by only one of these compounds, whereas a fourth subset was not activated by either compound. At -60 mV, the magnitude of the capsaicin-activated currents was about three times larger than the magnitude of the nicotine-activated currents. The current-voltage relationship of the nAChR exhibited marked rectification, such that for voltages > or = 0 mV the current was essentially zero. In contrast, the current-voltage relationship of the capsaicin-activated current was ohmic from +/- 60 mV. These data indicate the existence of subsets of capsaicin-sensitive afferent neurons.

Simulation of Na/K Pump Current-Voltage Relationship

1992 ◽  
Vol 671 (1 Ion-Motive AT) ◽  
pp. 449-451 ◽  
Author(s):  
X.-Y. LIU ◽  
T. A. KINARD ◽  
J. R. STIMERS
Keyword(s):  
Pump Current ◽  
Current Voltage ◽  
Current Voltage Relationship ◽  
Voltage Relationship

scholarly journals Ionic Basis of Membrane Potential and of Acetylcholine-evduced Currents in the Cell Body of the Cockroach Fast Coxal Depressor Motor Neurone

1990 ◽  
Vol 151 (1) ◽  
pp. 21-39 ◽  
Author(s):  
JONATHAN A. DAVID ◽  
DAVID B. SATTELLE
Keyword(s):  
Cell Body ◽  
Outward Current ◽  
Motor Neurone ◽  
Resting Potential ◽  
Inward Current ◽  
Current Voltage ◽  
Low K ◽  
Current Voltage Relationship ◽  
Ionic Basis ◽  
Voltage Relationship

The ionic basis of the resting potential and of the response to acetylcholine (ACh) has been investigated in the cell body membrane of the fast coxal depressor motor neurone in the metathoracic ganglion of the cockroach Periplaneta americana. By means of ion-sensitive microelectrodes, intracellular concentrations of three ion species were estimated (mmoll−1): [K+]i, 1443; [Na+]i, 9±1; [Cl−], 7±1. The resting potential of continuously superfused cells was −75.6±1.9mV at 22° C. A change in resting potential of 42.0±2.5mV accompanied a decade change in [K+]o. Experiments with (10−4moll−1) ouabain, Na+ injection, low temperature (10°C) and non-superfused cells indicated the presence of an electrogenic sodium pump. Under current-clamp, the cell body membrane was depolarized by sequentially applied, ionophoretic pulses (500ms duration) of ACh. Under voltage-clamp, such doses of ACh resulted in an inward current which was abolished in low-Na+ saline. Ion-sensitive electrodes revealed an increase in [Na+]i but no change in [Cl−1]j in response to externally applied ACh. The ACh-induced current-voltage relationship was shifted in a negative direction by low-K+ saline. The AChinduced inward current was usually followed by a delayed outward current which reversed at Ek. Low-K+ saline had the same effect on this outward component as depolarizing the membrane. This suggests that the outward current component is carried by K+. The ACh-induced inward current and the delayed outward current were potentiated either when [Ca2+]i was lowered by injecting the calcium chelator BAPTA or by exposure of the cell to low-Ca2+ saline. High-Ca2+ saline reduced the inward component of the response and produced a negative shift in the AChinduced current-voltage relationship. The amplitude of the delayed outward

Current-voltage relationship of the basolateral membrane of a tight epithelium

1979 ◽  
Vol 555 (3) ◽  
pp. 519-523 ◽  
Author(s):  
Nancy K. Wills ◽  
Douglas C. Eaton ◽  
Simon A. Lewis ◽  
Mark S. Ifshin
Keyword(s):  
Basolateral Membrane ◽  
Current Voltage ◽  
Relationship Of ◽  
Current Voltage Relationship ◽  
Voltage Relationship ◽  
Tight Epithelium
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