Current-voltage relationship in downward field-aligned current region

Abstract. The current-voltage relationship in the auroral particle acceleration region has been studied statistically by the Akebono (EXOS-D) satellite in terms of the charge carriers of the upward field-aligned current. The Akebono satellite often observed field-aligned currents which were significantly larger than the model value predicted by Knight (1973). We compared the upward field-aligned current estimated by three different methods, and found that low-energy electrons often play an important role as additional current carriers, together with the high-energy primary electrons which are expected from Knight's relation. Such additional currents have been observed especially at high and middle altitudes of the particle acceleration region. Some particular features of electron distribution functions, such as "cylindrical distribution functions" and "electron conics", have often been observed coinciding with the additional currents. They indicated time variability of the particle acceleration region. Therefore, we have concluded that the low-energy electrons within the "forbidden" region of electron phase space in the stationary model often contribute to charge carriers of the current because of the rapid time variability of the particle acceleration region. "Cylindrical distribution functions" are expected to be found below the time-varying potential difference. We statistically examined the locations of "cylindrical distribution function", and found that their altitudes are related to the location where the additional currents have been observed. This result is consistent with the idea that the low-energy electrons can also carry significant current when the acceleration region changes in time.

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

eLife ◽

10.7554/elife.25755 ◽

2017 ◽

Vol 6 ◽

Cited By ~ 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.

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

AJP Cell Physiology ◽

10.1152/ajpcell.1996.270.6.c1807 ◽

1996 ◽

Vol 270 (6) ◽

pp. C1807-C1814 ◽

Cited By ~ 43

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.

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Simulation of Na/K Pump Current-Voltage Relationship

Annals of the New York Academy of Sciences ◽

10.1111/j.1749-6632.1992.tb43826.x ◽

1992 ◽

Vol 671 (1 Ion-Motive AT) ◽

pp. 449-451 ◽

Cited By ~ 1

Author(s):

X.-Y. LIU ◽

T. A. KINARD ◽

J. R. STIMERS

Keyword(s):

Pump Current ◽

Current Voltage ◽

Current Voltage Relationship ◽

Voltage Relationship

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

Journal of Experimental Biology ◽

10.1242/jeb.151.1.21 ◽

1990 ◽

Vol 151 (1) ◽

pp. 21-39 ◽

Cited By ~ 1

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

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