A transient outward rectification in the cat sympathetic preganglionic neuron

1987 ◽  
Vol 408 (2) ◽  
pp. 207-208 ◽  
Author(s):  
M. Yoshimura ◽  
C. Polosa ◽  
S. Nishi
Keyword(s):  
Outward Rectification ◽  
Sympathetic Preganglionic Neuron

Ionic mechanisms for the subthreshold oscillations and differential electroresponsiveness of medial entorhinal cortex layer II neurons

1993 ◽  
Vol 70 (1) ◽  
pp. 144-157 ◽  
Author(s):  
R. Klink ◽  
A. Alonso
Keyword(s):  
Membrane Potential ◽  
Entorhinal Cortex ◽  
Inward Rectification ◽  
Voltage Level ◽  
Medial Entorhinal Cortex ◽  
Potential Oscillations ◽  
Subthreshold Oscillations ◽  
Outward Rectification ◽  
Ionic Mechanisms ◽  
Membrane Potential Oscillations

1. Layer II of the medial entorhinal cortex is composed of two electrophysiologically and morphologically distinct types of projection neurons: stellate cells (SCs), which are distinguished by rhythmic subthreshold oscillatory activity, and non-SCs. The ionic mechanisms underlying their differential electroresponsiveness, particularly in the subthreshold range of membrane potentials, were investigated in an "in vitro" slice preparation. 2. In both SCs and non-SCs, the apparent membrane input resistance was markedly voltage dependent, respectively decreasing or increasing at hyperpolarized or subthreshold depolarized potential levels. Thus the neurons displayed inward rectification in the hyperpolarizing and depolarizing range. 3. In the depolarizing range, inward rectification was blocked by tetrodotoxin (TTX, 1 microM) in both types of neurons and thus shown to depend on the presence of a persistent low-threshold Na+ conductance (gNap). However, in the presence of TTX, pronounced outward rectification became manifest in the subthreshold depolarizing range of membrane potentials (positive to -60 mV) in the SCs but not in the non-SCs. 4. The rhythmic subthreshold membrane potential oscillations that were present only in the SCs were abolished by TTX and not by Ca2+ conductance block with Cd2+ or Co2+. Subthreshold oscillations thus rely on the activation of voltage-gated Na+, and not Ca2+, conductances. The Ca2+ conductance block also had no effect on the subthreshold outward rectification. 5. Prominent time-dependent inward rectification in the hyperpolarizing range in the SCs persisted after Na(+)- and Ca2+ conductance block. This rectification was not affected by Ba2+ (1 mM), but was blocked by Cs+ (1-4 mM). Therefore, it is most probably generated by a hyperpolarization-activated cationic current (Q-like current). However, the Q-like current appears to play no major role in the generation of subthreshold rhythmic membrane potential oscillations, because these persisted in the presence of Cs+. 6. On the other hand, in the SCs, the fast, sustained, outward rectification that strongly developed (after Na+ conductance block) at the oscillatory voltage level was not affected by Cs+ but was blocked by Ba2+ (1 mM). Barium was also effective in blocking the subthreshold membrane potential oscillations. 7. In the non-SCs, which do not generate subthreshold rhythmic membrane potential oscillations or manifest subthreshold outward rectification in TTX, Ca2+ conductance block abolished spike repolarization and caused the development of long-lasting Na(+)-dependent plateau potentials at a high suprathreshold voltage level. At this level, where prominent delayed rectification is present, the Na+ plateaus sustained rhythmic membrane potential oscillations.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Action Potentials in Rhodnius Oocytes: Repolarization is Sensitive to Potassium Channel Blockers

1986 ◽  
Vol 126 (1) ◽  
pp. 119-132
Author(s):  
M. J. O'DONNELL
Keyword(s):  
Potassium Channel ◽  
Action Potentials ◽  
Potassium Conductance ◽  
Channel Blockers ◽  
Calcium Dependent ◽  
Outward Rectification ◽  
Current Voltage ◽  
Potassium Channel Blockers ◽  
Potassium Conductances ◽  
Voltage Dependent

Depolarization of Rhodnius oocytes evokes action potentials (APs) whose rising phase is calcium-dependent. The ionic basis for the repolarizing (i.e. falling) phase of the AP was examined. Addition of potassium channel blockers (tetraethylammonium, tetrabutylammonium, 4-aminopyridine, atropine) to the bathing saline increased the duration and overshoot of APs. Intracellular injection of tetraethyl ammonium had similar effects. These results suggest that a voltage-dependent potassium conductance normally contributes to repolarization. Repolarization does not require a chloride influx, because substitution of impermeant anions for chloride did not increase AP duration. AP duration and overshoot actually decreased progressively when chloride levels were reduced. Current/voltage curves show inward and outward rectification, properties often associated with potassium conductances. Outward rectification was largely blocked by external tetraethylammonium. Possible functions of the rectifying properties of the oocyte membrane are discussed.

Physiological Properties of Central Medial and Central Lateral Amygdala Neurons

1999 ◽  
Vol 82 (4) ◽  
pp. 1843-1854 ◽  
Author(s):  
Marzia Martina ◽  
Sébastien Royer ◽  
Denis Paré
Keyword(s):  
Conditioned Fear ◽  
Brain Slices ◽  
Cell Types ◽  
Membrane Depolarization ◽  
Membrane Properties ◽  
Repetitive Firing ◽  
Inward Rectification ◽  
Current Pulses ◽  
Outward Rectification ◽  
Physiological Properties

Mounting evidence implicates the central (CE) nucleus of the amygdala in the mediation of classically conditioned fear responses. However, little data are available regarding the intrinsic membrane properties of CE amygdala neurons. Here, we characterized the physiological properties of CE medial (CEM) and CE lateral (CEL) amygdala neurons using whole cell recordings in brain slices maintained in vitro. Several classes of CE neurons were distinguished on the basis of their physiological properties. Most CEM cells (95%), here termed “late-firing neurons,” displayed a marked voltage- and time-dependent outward rectification in the depolarizing direction. This phenomenon was associated with a conspicuous delay between the onset of depolarizing current pulses and the first action potential. During this delay, the membrane potential ( V m) depolarized slowly, the steepness of this depolarizing ramp increasing as the prepulse V m was hyperpolarized from −60 to −90 mV. Low extracellular concentrations of 4-aminopyridine (30 μM) reversibly abolished the outward rectification and the delay to firing. Late-firing CEM neurons displayed a continuum of repetitive firing properties with cells generating single spikes at one pole and high-frequency (≥90 Hz) spike bursts at the other. In contrast, only 56% of CEL cells displayed the late-firing behavior prevalent among CEM neurons. Moreover, these CEL neurons only generated single spikes in response to membrane depolarization. A second major class of CEL cells (38%) lacked the characteristic delay to firing observed in CEM cells, generated single spikes in response to membrane depolarization, and displayed various degrees of inward rectification in the hyperpolarizing direction. In both regions of the CE nucleus, two additional cell types were encountered infrequently (≤ 6% of our samples). One type of neurons, termed “low-threshold bursting cells” had a behavior reminiscent of thalamocortical neurons. The second type of cells, called “fast-spiking cells,” generated brief action potentials at high rates with little spike frequency adaptation in response to depolarizing current pulses. These findings indicate that the CE nucleus contains several types of neurons endowed with distinct physiological properties. Moreover, these various cell types are not distributed uniformly in the medial and lateral sector of the CE nucleus. This heterogeneity parallels anatomic data indicating that these subnuclei are part of different circuits.

scholarly journals Outward Rectification of Voltage-Gated K+ Channels Evolved at Least Twice in Life History

PLoS ONE ◽  
2015 ◽  
Vol 10 (9) ◽  
pp. e0137600 ◽  
Author(s):  
Janin Riedelsberger ◽  
Ingo Dreyer ◽  
Wendy Gonzalez
Keyword(s):  
Life History ◽  
K Channels ◽  
Voltage Gated ◽  
Outward Rectification

Membrane properties of rat substantia gelatinosa neurons in vitro

1989 ◽  
Vol 62 (1) ◽  
pp. 109-118 ◽  
Author(s):  
M. Yoshimura ◽  
T. M. Jessell
Keyword(s):  
Time Dependent ◽  
Substantia Gelatinosa ◽  
Membrane Properties ◽  
Resting Potential ◽  
Inward Rectification ◽  
Resting Membrane Potential ◽  
Membrane Hyperpolarization ◽  
Anomalous Rectification ◽  
Outward Rectification

1. The membrane properties of substantia gelatinosa (SG) neurons in an in vitro adult rat transverse spinal cord slice preparation with attached dorsal root have been examined. Intracellular recordings were obtained from identified SG neurons. 2. Seventy-six percent of SG neurons exhibited a time-dependent anomalous rectification (AR) when the membrane was hyperpolarized from the resting potential. The time-dependent AR was blocked by cesium (Cs+, 2 mM) but not by barium (Ba2+, 2 mM). Application of Cs+ itself caused membrane hyperpolarization in those SG neurons that expressed the time-dependent AR. The activation of the time-dependent AR was maximal at potentials 5-10 mV below the resting membrane potential. 3. In a few SG neurons, the current-voltage relationship revealed a marked inward rectification, even though there was no detectable time-dependent anomalous rectification during hyperpolarization. Analysis of the Ba2+- and Cs+-sensitivity of these neurons confirmed that SG neurons expressed two distinct ARs, one of which is fast and Ba2+-sensitive and the other of which is time-dependent and Ba2+-insensitive. 4. Fifty-one percent of SG neurons exhibited a transient outward rectification when hyperpolarizing current pulses were applied from potentials more positive than -60 mV or when depolarizing pulses were applied from potentials more negative than -65 mV. The transient outward rectification persisted for 0.3-2 s when hyperpolarizing pulses were applied at -55 mV. 5. The transient outward rectification was associated with a decrease in membrane resistance and was enhanced in low K+ solutions. 4-aminopyridine (4-AP, 2 mM) reversibly blocked the transient outward rectification. 6. The time-dependent anomalous and transient outward rectifying currents exerted opposite effects on the firing properties of SG neurons. Activation of the time-dependent AR increased neuronal excitability. In neurons that exhibited the time-dependent AR, membrane depolarization caused the appearance of a rebound depolarization that resulted in the generation of spikes with only a short delay after application of the depolarizing pulse. In contrast, the transient outward rectifying current markedly delayed spike firing in response to depolarizing pulses. This delay was blocked by application of 4-AP. 7. The diversity in response properties of subpopulations of SG neurons may result in part from this heterogeneity in membrane properties.

Characteristics of the sympathetic preganglionic neuron and its synaptic input

1988 ◽  
Vol 31 (1) ◽  
pp. 47-84 ◽  
Author(s):  
W. Laskey ◽  
C. Polosa
Keyword(s):  
Synaptic Input ◽  
Sympathetic Preganglionic Neuron
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