Expression and functions of N-type Cav2.2 and T-type Cav3.1 channels in rat vasopressin neurons under normotonic conditions

Abstract Arginine vasopressin (AVP) neurons play essential roles in sensing the change in systemic osmolarity and regulating AVP release from their neuronal terminals to maintain the plasma osmolarity. AVP exocytosis depends on the Ca2+ entry via voltage-gated Ca2+ channels (VGCCs) in AVP neurons. In this study, suppression by siRNA-mediated knockdown and pharmacological sensitivity of VGCC currents evidenced molecular and functional expression of N-type Cav2.2 and T-type Cav3.1 in AVP neurons under normotonic conditions. Also, both the Cav2.2 and Cav3.1 currents were found to be sensitive to flufenamic acid (FFA). TTX-insensitive spontaneous action potentials were suppressed by FFA and T-type VGCC blocker Ni2+. However, Cav2.2-selective ω-conotoxin GVIA failed to suppress the firing activity. Taken together, it is concluded that Cav2.2 and Cav3.1 are molecularly and functionally expressed and both are sensitive to FFA in unstimulated rat AVP neurons. Also, it is suggested that Cav3.1 is primarily involved in their action potential generation.

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Spontaneous Action Potentials and Neural Coding in Unmyelinated Axons

Neural Computation ◽

10.1162/neco_a_00705 ◽

2015 ◽

Vol 27 (4) ◽

pp. 801-818 ◽

Cited By ~ 1

Author(s):

Cian O’Donnell ◽

Mark C. W. van Rossum

Keyword(s):

Action Potentials ◽

Neural Coding ◽

Unmyelinated Axon ◽

Action Potential Generation ◽

Potential Generation ◽

Unmyelinated Axons ◽

Single Compartment ◽

Spatially Extended ◽

Spontaneous Action ◽

Spontaneous Action Potentials

The voltage-gated Na and K channels in neurons are responsible for action potential generation. Because ion channels open and close in a stochastic fashion, spontaneous (ectopic) action potentials can result even in the absence of stimulation. While spontaneous action potentials have been studied in detail in single-compartment models, studies on spatially extended processes have been limited. The simulations and analysis presented here show that spontaneous rate in unmyelinated axon depends nonmonotonically on the length of the axon, that the spontaneous activity has sub-Poisson statistics, and that neural coding can be hampered by the spontaneous spikes by reducing the probability of transmitting the first spike in a train.

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The functional expression of the Lamin A/C mutant Q517X in HL1 cardiomyocytes causes nuclear and cytoskeleton remodeling with reduction in spontaneous action potentials frequency

Vascular Pharmacology ◽

10.1016/j.vph.2020.106724 ◽

2020 ◽

Vol 132 ◽

pp. 106724

Author(s):

Andrea Gerbino ◽

Roberta De Zio ◽

Cinzia Forleo ◽

Serena Milano ◽

Giuseppe Procino ◽

...

Keyword(s):

Action Potentials ◽

Functional Expression ◽

Lamin A ◽

Cytoskeleton Remodeling ◽

Spontaneous Action ◽

Spontaneous Action Potentials

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SK Current, Expressed During the Development and Regeneration of Chick Hair Cells, Contributes to the Patterning of Spontaneous Action Potentials

Frontiers in Cellular Neuroscience ◽

10.3389/fncel.2021.766264 ◽

2022 ◽

Vol 15 ◽

Author(s):

Snezana Levic

Keyword(s):

Electrical Activity ◽

Hair Cells ◽

Action Potentials ◽

Functional Expression ◽

Basilar Papilla ◽

Spontaneous Electrical Activity ◽

Intracellular Ca ◽

Spontaneous Action ◽

Spontaneous Action Potentials

Chick hair cells display calcium (Ca2+)-sensitive spontaneous action potentials during development and regeneration. The role of this activity is unclear but thought to be involved in establishing proper synaptic connections and tonotopic maps, both of which are instrumental to normal hearing. Using an electrophysiological approach, this work investigated the functional expression of Ca2+-sensitive potassium [IK(Ca)] currents and their role in spontaneous electrical activity in the developing and regenerating hair cells (HCs) in the chick basilar papilla. The main IK(Ca) in developing and regenerating chick HCs is an SK current, based on its sensitivity to apamin. Analysis of the functional expression of SK current showed that most dramatic changes occurred between E8 and E16. Specifically, there is a developmental downregulation of the SK current after E16. The SK current gating was very sensitive to the availability of intracellular Ca2+ but showed very little sensitivity to T-type voltage-gated Ca2+ channels, which are one of the hallmarks of developing and regenerating hair cells. Additionally, apamin reduced the frequency of spontaneous electrical activity in HCs, suggesting that SK current participates in patterning the spontaneous electrical activity of HCs.

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