scholarly journals Simultaneous mapping of membrane voltage and calcium in zebrafish heart in vivo reveals chamber-specific developmental transitions in ionic currents

2014 ◽  
Vol 5 ◽  
Author(s):  
Jennifer H. Hou ◽  
Joel M. Kralj ◽  
Adam D. Douglass ◽  
Florian Engert ◽  
Adam E. Cohen
Keyword(s):  
Ionic Currents ◽  
Membrane Voltage ◽  
Developmental Transitions ◽  
Zebrafish Heart

Electrophysiological characterization and computational models of HVC neurons in the zebra finch

2013 ◽  
Vol 110 (5) ◽  
pp. 1227-1245 ◽  
Author(s):  
Arij Daou ◽  
Matthew T. Ross ◽  
Frank Johnson ◽  
Richard L. Hyson ◽  
Richard Bertram
Keyword(s):  
Computational Models ◽  
Premotor Cortex ◽  
Brain Slices ◽  
Ionic Currents ◽  
Proper Name ◽  
Using Data ◽  
Electrophysiological Characterization

The nucleus HVC (proper name) within the avian analog of mammal premotor cortex produces stereotyped instructions through the motor pathway leading to precise, learned vocalization by songbirds. Electrophysiological characterization of component HVC neurons is an important requirement in building a model to understand HVC function. The HVC contains three neural populations: neurons that project to the RA (robust nucleus of arcopallium), neurons that project to Area X (of the avian basal ganglia), and interneurons. These three populations are interconnected with specific patterns of excitatory and inhibitory connectivity, and they fire with characteristic patterns both in vivo and in vitro. We performed whole cell current-clamp recordings on HVC neurons within brain slices to examine their intrinsic firing properties and determine which ionic currents are responsible for their characteristic firing patterns. We also developed conductance-based models for the different neurons and calibrated the models using data from our brain slice work. These models were then used to generate predictions about the makeup of the ionic currents that are responsible for the different responses to stimuli. These predictions were then tested and verified in the slice using pharmacological manipulations. The model and the slice work highlight roles of a hyperpolarization-activated inward current ( Ih), a low-threshold T-type Ca2+ current ( ICa-T), an A-type K+ current ( IA), a Ca2+-activated K+ current ( ISK), and a Na+-dependent K+ current ( IKNa) in driving the characteristic neural patterns observed in the three HVC neuronal populations. The result is an improved characterization of the HVC neurons responsible for song production in the songbird.

On the Origin of the Extracellular Action Potential Waveform: A Modeling Study

2006 ◽  
Vol 95 (5) ◽  
pp. 3113-3128 ◽  
Author(s):  
Carl Gold ◽  
Darrell A. Henze ◽  
Christof Koch ◽  
György Buzsáki
Keyword(s):  
Action Potential ◽  
Pyramidal Neurons ◽  
Ionic Currents ◽  
Dendritic Morphology ◽  
Electrode Position ◽  
Unit Recording ◽  
Extracellular Recordings ◽  
Ca1 Pyramidal Neurons ◽  
Varied Composition

Although extracellular unit recording is typically used for the detection of spike occurrences, it also has the theoretical ability to report about what are typically considered intracellular features of the action potential. We address this theoretical ability by developing a model system that captures features of experimentally recorded simultaneous intracellular and extracellular recordings of CA1 pyramidal neurons. We use the line source approximation method of Holt and Koch to model the extracellular action potential (EAP) voltage resulting from the spiking activity of individual neurons. We compare the simultaneous intracellular and extracellular recordings of CA1 pyramidal neurons recorded in vivo with model predictions for the same cells reconstructed and simulated with compartmental models. The model accurately reproduces both the waveform and the amplitude of the EAPs, although it was difficult to achieve simultaneous good matches on both the intracellular and extracellular waveforms. This suggests that accounting for the EAP waveform provides a considerable constraint on the overall model. The developed model explains how and why the waveform varies with electrode position relative to the recorded cell. Interestingly, each cell's dendritic morphology had very little impact on the EAP waveform. The model also demonstrates that the varied composition of ionic currents in different cells is reflected in the features of the EAP.

scholarly journals In vivo cardiac reprogramming contributes to zebrafish heart regeneration

Nature ◽  
2013 ◽  
Vol 498 (7455) ◽  
pp. 497-501 ◽  
Author(s):  
Ruilin Zhang ◽  
Peidong Han ◽  
Hongbo Yang ◽  
Kunfu Ouyang ◽  
Derek Lee ◽  
...  
Keyword(s):  
Heart Regeneration ◽  
Zebrafish Heart

scholarly journals Cellular and Network Models for Intrathalamic Augmenting Responses During 10-Hz Stimulation

1998 ◽  
Vol 79 (5) ◽  
pp. 2730-2748 ◽  
Author(s):  
Maxim Bazhenov ◽  
Igor Timofeev ◽  
Mircea Steriade ◽  
Terrence J. Sejnowski
Keyword(s):  
Network Model ◽  
Network Models ◽  
Ionic Currents ◽  
Repetitive Stimulation ◽  
Aminobutyric Acid ◽  
Single Pair ◽  
Inhibitory Postsynaptic Potentials ◽  
Low Threshold ◽  
Stimulation Of

Bazhenov, Maxim, Igor Timofeev, Mircea Steriade, and Terrence J. Sejnowski. Cellular and network models for intrathalamic augmenting responses during 10-Hz stimulation. J. Neurophysiol. 79: 2730–2748, 1998. Repetitive stimulation of the thalamus at7–14 Hz evokes responses of increasing amplitude in the thalamus and the areas of the neocortex to which the stimulated foci project. Possible mechanisms underlying the thalamic augmenting responses during repetitive stimulation were investigated with computer models of interacting thalamocortical (TC) and thalamic reticular (RE) cells. The ionic currents in these cells were modeled with Hodgkin-Huxley type of kinetics, and the results of the model were compared with in vivo thalamic recordings from decorticated cats. The simplest network model demonstrating an augmenting response was a single pair of coupled RE and TC cells, in which RE-induced inhibitory postsynaptic potentials (IPSPs) in the TC cell led to progressive deinactivation of a low-threshold Ca2+ current. The augmenting responses in two reciprocally interacting chains of RE and TC cells depended also on γ-aminobutyric acid-B (GABAB) IPSPs. Lateral GABAA inhibition between identical RE cells, which weakened bursts in these cells, diminished GABAB IPSPs and delayed the augmenting response in TC cells. The results of these simulations show that the interplay between existing mechanisms in the thalamus explains the basic properties of the intrathalamic augmenting responses.

scholarly journals Effectiveness in Block by Dexmedetomidine of Hyperpolarization-Activated Cation Current, Independent of Its Agonistic Effect on α2-Adrenergic Receptors

2020 ◽  
Vol 21 (23) ◽  
pp. 9110
Author(s):  
Te-Ling Lu ◽  
Te-Jung Lu ◽  
Sheng-Nan Wu
Keyword(s):  
Adrenergic Receptors ◽  
Time Course ◽  
Ionic Currents ◽  
Inhibitory Effect ◽  
Firing Frequency ◽  
Neuroendocrine Cells ◽  
Gh3 Cells ◽  
Membrane Excitability ◽  
Cation Current

Dexmedetomidine (DEX), a highly selective agonist of α2-adrenergic receptors, has been tailored for sedation without risk of respiratory depression. Our hypothesis is that DEX produces any direct perturbations on ionic currents (e.g., hyperpolarization-activated cation current, Ih). In this study, addition of DEX to pituitary GH3 cells caused a time- and concentration-dependent reduction in the amplitude of Ih with an IC50 value of 1.21 μM and a KD value of 1.97 μM. A hyperpolarizing shift in the activation curve of Ih by 10 mV was observed in the presence of DEX. The voltage-dependent hysteresis of Ih elicited by long-lasting triangular ramp pulse was also dose-dependently reduced during its presence. In continued presence of DEX (1 μM), further addition of OXAL (10 μM) or replacement with high K+ could reverse DEX-mediated inhibition of Ih, while subsequent addition of yohimbine (10 μM) did not attenuate the inhibitory effect on Ih amplitude. The addition of 3 μM DEX mildly suppressed the amplitude of erg-mediated K+ current. Under current-clamp potential recordings, the exposure to DEX could diminish the firing frequency of spontaneous action potentials. In pheochromocytoma PC12 cells, DEX was effective at suppressing Ih together with a slowing in activation time course of the current. Taken together, findings from this study strongly suggest that during cell exposure to DEX used at clinically relevant concentrations, the DEX-mediated block of Ih appears to be direct and would particularly be one of the ionic mechanisms underlying reduced membrane excitability in the in vivo endocrine or neuroendocrine cells.

scholarly journals The Histone H3 Acetylase dGcn5 Is a Key Player in Drosophila melanogaster Metamorphosis

2005 ◽  
Vol 25 (18) ◽  
pp. 8228-8238 ◽  
Author(s):  
Clément Carré ◽  
Dimitri Szymczak ◽  
Josette Pidoux ◽  
Christophe Antoniewski
Keyword(s):  
Drosophila Melanogaster ◽  
Histone H3 ◽  
Noticeable Effect ◽  
Developmental Transitions ◽  
Isolation And Characterization ◽  
Lysine Residues ◽  
Developmental Role ◽  
Variant Protein

ABSTRACT Although it has been well established that histone acetyltransferases (HATs) are involved in the modulation of chromatin structure and gene transcription, there is only little information on their developmental role in higher organisms. Gcn5 was the first transcription factor with HAT activity identified in eukaryotes. Here we report the isolation and characterization of Drosophila melanogaster dGcn5 mutants. Null dGcn5 alleles block the onset of both oogenesis and metamorphosis, while hypomorphic dGcn5 alleles impair the formation of adult appendages and cuticle. Strikingly, the dramatic loss of acetylation of the K9 and K14 lysine residues of histone H3 in dGcn5 mutants has no noticeable effect on larval tissues. In contrast, strong cell proliferation defects in imaginal tissues are observed. In vivo complementation experiments revealed that dGcn5 integrates specific functions in addition to chromosome binding and acetylation. Surprisingly, a dGcn5 variant protein with a deletion of the bromodomain, which has been shown to recognize acetylated histones, appears to be fully functional. Our results establish dGcn5 as a major histone H3 acetylase in Drosophila which plays a key role in the control of specific morphogenetic cascades during developmental transitions.

scholarly journals Augmented line-scan focal modulation microscopy for multi-dimensional imaging of zebrafish heart in vivo

2017 ◽  
Vol 8 (12) ◽  
pp. 5698 ◽  
Author(s):  
Shilpa Pant ◽  
Yubo Duan ◽  
Fei Xiong ◽  
Nanguang Chen
Keyword(s):  
Line Scan ◽  
Zebrafish Heart

scholarly journals In vivo development of voltage-dependent ionic currents in embryonic Xenopus spinal neurons

1993 ◽  
Vol 13 (6) ◽  
pp. 2575-2581 ◽  
Author(s):  
MG Desarmenien ◽  
B Clendening ◽  
NC Spitzer
Keyword(s):  
Ionic Currents ◽  
Spinal Neurons ◽  
Voltage Dependent

scholarly journals Evolving Mechanistic Concepts of Epileptiform Synchronization and their Relevance in Curing Focal Epileptic Disorders

2019 ◽  
Vol 17 (9) ◽  
pp. 830-842 ◽  
Author(s):  
Maxime Lévesque ◽  
David Ragsdale ◽  
Massimo Avoli
Keyword(s):  
Epileptiform Activity ◽  
Ionic Currents ◽  
Pharmacological Treatments ◽  
Voltage Gated ◽  
Epileptic Patients ◽  
Inhibitory Signaling ◽  
Synaptic Mechanisms

The synchronized activity of neuronal networks under physiological conditions is mirrored by specific oscillatory patterns of the EEG that are associated with different behavioral states and cognitive functions. Excessive synchronization can, however, lead to focal epileptiform activity characterized by interictal and ictal discharges in epileptic patients and animal models. This review focusses on studies that have addressed epileptiform synchronization in temporal lobe regions by employing in vitro and in vivo recording techniques. First, we consider the role of ionotropic and metabotropic excitatory glutamatergic transmission in seizure generation as well as the paradoxical role of GABAA signaling in initiating and perhaps maintaining focal seizure activity. Second, we address non-synaptic mechanisms (which include voltage-gated ionic currents and gap junctions) in the generation of epileptiform synchronization. For each mechanism, we discuss the actions of antiepileptic drugs that are presumably modulating excitatory or inhibitory signaling and voltage-gated currents to prevent seizures in epileptic patients. These findings provide insights into the mechanisms of seizure initiation and maintenance, thus leading to the development of specific pharmacological treatments for focal epileptic disorders.

scholarly journals Evidence for Effective Inhibitory Actions on Hyperpolarization-Activated Cation Current Caused by Ganoderma Triterpenoids, the Main Active Constitutents of Ganoderma Spores

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4256 ◽  
Author(s):  
Wei-Ting Chang ◽  
Zi-Han Gao ◽  
Yi-Ching Lo ◽  
Sheng-Nan Wu
Keyword(s):  
Ionic Currents ◽  
Inhibitory Effect ◽  
Firing Frequency ◽  
Gh3 Cells ◽  
Heart Cells ◽  
Excitable Cells ◽  
Cell Current ◽  
Spontaneous Action

The triterpenoid fraction of Ganoderma (Ganoderma triterpenoids, GTs) has been increasingly demonstrated to provide effective antioxidant, neuroprotective or cardioprotective activities. However, whether GTs is capable of perturbing the transmembrane ionic currents existing in electrically excitable cells is not thoroughly investigated. In this study, an attempt was made to study whether GTs could modify hyperpolarization-activated cation currents (Ih) in pituitary tumor (GH3) cells and in HL-1 atrial cardiomyocytes. In whole-cell current recordings, the addition of GTs produced a dose-dependent reduction in the amplitude of Ih in GH3 cells with an IC50 value of 11.7 µg/mL, in combination with a lengthening in activation time constant of the current. GTs (10 µg/mL) also caused a conceivable shift in the steady-state activation curve of Ih along the voltage axis to a more negative potential by approximately 11 mV. Subsequent addition of neither 8-cyclopentyl-1,3-dipropylxanthine nor 8-(p-sulfophenyl)theophylline, still in the presence of GTs, could attenuate GTs-mediated inhibition of Ih. In current-clamp voltage recordings, GTs diminished the firing frequency of spontaneous action potentials in GH3 cells, and it also decreased the amplitude of sag potential in response to hyperpolarizing current stimuli. In murine HL-1 cardiomyocytes, the GTs addition also suppressed the amplitude of Ih effectively. In DPCPX (1 µM)-treated HL-1 cells, the inhibitory effect of GTs on Ih remained efficacious. Collectively, the inhibition of Ih caused by GTs is independent of its possible binding to adenosine receptors and it might have profound influence in electrical behaviors of different types of electrically excitable cells (e.g., pituitary and heart cells) if similar in vitro or in vivo findings occur.

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