Contribution of blocked potassium current conductance and increased conductance of persistent sodium current to the afterdischarge in myelinated neuron

2012 ◽  
Vol 46 (2) ◽  
pp. 297-299 ◽  
Author(s):  
Sheng-Nan Wu ◽  
Yi-Ching Lo ◽  
Bing-Shuo Chen ◽  
Edmund Cheung So ◽  
Li-Tzong Chen
Keyword(s):  
Potassium Current ◽  
Sodium Current ◽  
Persistent Sodium Current ◽  
Current Conductance

Subthreshold Sodium Current Underlies Essential Functional Specializations at Primary Auditory Afferents

2008 ◽  
Vol 99 (4) ◽  
pp. 1683-1699 ◽  
Author(s):  
Sebastián Curti ◽  
Leonel Gómez ◽  
Ruben Budelli ◽  
Alberto E. Pereda
Keyword(s):  
Auditory Processing ◽  
Potassium Current ◽  
Sodium Current ◽  
Persistent Sodium Current ◽  
Essential Information ◽  
Mauthner Cell ◽  
Auditory Afferents ◽  
Electrical Resonance ◽  
Chemical Synapses ◽  
Activity Dependent

Primary auditory afferents are generally perceived as passive, timing-preserving lines of communication. Contrasting this view, identifiable auditory afferents to the goldfish Mauthner cell undergo potentiation of their mixed—electrical and chemical—synapses in response to high-frequency bursts of activity. This property likely represents a mechanism of input sensitization because they provide the Mauthner cell with essential information for the initiation of an escape response. Consistent with this synaptic specialization, we show here that these afferents exhibit an intrinsic ability to respond with bursts of 200–600 Hz and this property critically relies on the activation of a persistent sodium current, which is counterbalanced by the delayed activation of an A-type potassium current. Furthermore, the interaction between these conductances with the membrane passive properties supports the presence of electrical resonance, whose frequency preference is consistent with both the effective range of hearing in goldfish and the firing frequencies required for synaptic facilitation, an obligatory requisite for the induction of activity-dependent changes. Thus our data show that the presence of a persistent sodium current is functionally essential and allows these afferents to translate behaviorally relevant auditory signals into patterns of activity that match the requirements of their fast and highly modifiable synapses. The functional specializations of these neurons suggest that auditory afferents might be capable of more sophisticated contributions to auditory processing than has been generally recognized.

Sodium Currents in Neurons From the Rostroventrolateral Medulla of the Rat

2003 ◽  
Vol 90 (3) ◽  
pp. 1635-1642 ◽  
Author(s):  
Ilya A. Rybak ◽  
Krzysztof Ptak ◽  
Natalia A. Shevtsova ◽  
Donald R. McCrimmon
Keyword(s):  
Sodium Channels ◽  
Sodium Current ◽  
Cell Voltage ◽  
Kinetic Properties ◽  
Persistent Sodium Current ◽  
Sodium Currents ◽  
Bötzinger Complex ◽  
Window Current ◽  
Bursting Activity

Rapidly inactivating and persistent sodium currents have been characterized in acutely dissociated neurons from the area of rostroventrolateral medulla that included the pre-Bötzinger Complex. As demonstrated in many studies in vitro, this area can generate endogenous rhythmic bursting activity. Experiments were performed on neonate and young rats (P1-15). Neurons were investigated using the whole cell voltage-clamp technique. Standard activation and inactivation protocols were used to characterize the steady-state and kinetic properties of the rapidly inactivating sodium current. Slow depolarizing ramp protocols were used to characterize the noninactivating sodium current. The “window” component of the rapidly inactivating sodium current was calculated using mathematical modeling. The persistent sodium current was revealed by subtraction of the window current from the total noninactivating sodium current. Our results provide evidence of the presence of persistent sodium currents in neurons of the rat rostroventrolateral medulla and determine voltage-gated characteristics of activation and inactivation of rapidly inactivating and persistent sodium channels in these neurons.

Protease-Activated Receptor-1 Mediates Thrombin-Induced Persistent Sodium Current in Human Cardiomyocytes

2008 ◽  
Vol 73 (6) ◽  
pp. 1622-1631 ◽  
Author(s):  
Caroline Pinet ◽  
Vincent Algalarrondo ◽  
Sylvie Sablayrolles ◽  
Bruno Le Grand ◽  
Christophe Pignier ◽  
...  
Keyword(s):  
Sodium Current ◽  
Persistent Sodium Current ◽  
Human Cardiomyocytes ◽  
Protease Activated Receptor 1

scholarly journals Y1767C, a Novel SCN5A Mutation Induces a Persistent Sodium Current and Potentiates Ranolazine Inhibition of NaV1.5 Channels

2011 ◽  
Vol 100 (3) ◽  
pp. 421a
Author(s):  
Hai Huang ◽  
Silvia G. Priori ◽  
Carlo Napolitano ◽  
Michael E. O’Leary ◽  
Mohamed Chahine
Keyword(s):  
Sodium Current ◽  
Persistent Sodium Current ◽  
Scn5a Mutation

scholarly journals Electrophysiological Properties of Inferior Olive Neurons: A Compartmental Model

1999 ◽  
Vol 82 (2) ◽  
pp. 804-817 ◽  
Author(s):  
Nicolas Schweighofer ◽  
Kenji Doya ◽  
Mitsuo Kawato
Keyword(s):  
Calcium Current ◽  
Potassium Current ◽  
Inferior Olive ◽  
Sodium Current ◽  
Electrical Coupling ◽  
Biophysical Model ◽  
Delayed Rectifier ◽  
High Threshold ◽  
Electrophysiological Properties

As a step in exploring the functions of the inferior olive, we constructed a biophysical model of the olivary neurons to examine their unique electrophysiological properties. The model consists of two compartments to represent the known distribution of ionic currents across the cell membrane, as well as the dendritic location of the gap junctions and synaptic inputs. The somatic compartment includes a low-threshold calcium current ( I Ca_l), an anomalous inward rectifier current ( I h), a sodium current ( I Na), and a delayed rectifier potassium current ( I K_dr). The dendritic compartment contains a high-threshold calcium current ( I Ca_h), a calcium-dependent potassium current ( I K_Ca), and a current flowing into other cells through electrical coupling ( I c). First, kinetic parameters for these currents were set according to previously reported experimental data. Next, the remaining free parameters were determined to account for both static and spiking properties of single olivary neurons in vitro. We then performed a series of simulated pharmacological experiments using bifurcation analysis and extensive two-parameter searches. Consistent with previous studies, we quantitatively demonstrated the major role of I Ca_l in spiking excitability. In addition, I h had an important modulatory role in the spike generation and period of oscillations, as previously suggested by Bal and McCormick. Finally, we investigated the role of electrical coupling in two coupled spiking cells. Depending on the coupling strength, the hyperpolarization level, and the I Ca_l and I hmodulation, the coupled cells had four different synchronization modes: the cells could be in-phase, phase-shifted, or anti-phase or could exhibit a complex desynchronized spiking mode. Hence these simulation results support the counterintuitive hypothesis that electrical coupling can desynchronize coupled inferior olive cells.

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