scholarly journals Complex Regulation of Voltage-dependent Activation and Inactivation Properties of Retinal Voltage-gated Cav1.4 L-type Ca2+Channels by Ca2+-binding Protein 4 (CaBP4)

2012 ◽  
Vol 287 (43) ◽  
pp. 36312-36321 ◽  
Author(s):  
Lior Shaltiel ◽  
Christos Paparizos ◽  
Stefanie Fenske ◽  
Sami Hassan ◽  
Christian Gruner ◽  
...  
Keyword(s):  
Binding Protein ◽  
Voltage Gated ◽  
Voltage Dependent ◽  
Complex Regulation ◽  
Ca2 Channels

scholarly journals A Complex of RIM2alpha and RIM-Binding Protein 2 Stabilizes Slow Voltage-Dependent Inactivation of Cochlear Inner Hair Cell Cav1.3 L-Type Ca2+ Channels

2018 ◽  
Vol 114 (3) ◽  
pp. 637a-638a
Author(s):  
Nadine J. Ortner ◽  
Alexandra Pinggera ◽  
Anita Siller ◽  
Nadja Hofer ◽  
Niels Brandt ◽  
...  
Keyword(s):  
Hair Cell ◽  
Binding Protein ◽  
Inner Hair Cell ◽  
Dependent Inactivation ◽  
Voltage Dependent ◽  
Ca2 Channels

scholarly journals Voltage-gated transient currents in bovine adrenal fasciculata cells. I. T-type Ca2+ current.

1993 ◽  
Vol 102 (2) ◽  
pp. 217-237 ◽  
Author(s):  
B Mlinar ◽  
B A Biagi ◽  
J J Enyeart
Keyword(s):  
Time Constant ◽  
Low Voltage ◽  
Zona Fasciculata ◽  
Patch Clamp Technique ◽  
Time Constants ◽  
Voltage Gated ◽  
Wide Range ◽  
Boltzmann Function ◽  
Voltage Dependent ◽  
Ca2 Channels

The whole cell version of the patch clamp technique was used to identify and characterize voltage-gated Ca2+ channels in enzymatically dissociated bovine adrenal zona fasciculata (AZF) cells. The great majority of cells (84 of 86) expressed only low voltage-activated, rapidly inactivating Ca2+ current with properties of T-type Ca2+ current described in other cells. Voltage-dependent activation of this current was fit by a Boltzmann function raised to an integer power of 4 with a midpoint at -17 mV. Independent estimates of the single channel gating charge obtained from the activation curve and using the "limiting logarithmic potential sensitivity" were 8.1 and 6.8 elementary charges, respectively. Inactivation was a steep function of voltage with a v1/2 of -49.9 mV and a slope factor K of 3.73 mV. The expression of a single Ca2+ channel subtype by AZF cells allowed the voltage-dependent gating and kinetic properties of T current to be studied over a wide range of potentials. Analysis of the gating kinetics of this Ca2+ current indicate that T channel activation, inactivation, deactivation (closing), and reactivation (recovery from inactivation) each include voltage-independent transitions that become rate limiting at extreme voltages. Ca2+ current activated with voltage-dependent sigmoidal kinetics that were described by an m4 model. The activation time constant varied exponentially at test potentials between -30 and +10 mV, approaching a voltage-independent minimum of 1.6 ms. The inactivation time constant (tau i) also decreased exponentially to a minimum of 18.3 ms at potentials positive to 0 mV. T channel closing (deactivation) was faster at more negative voltages; the deactivation time constant (tau d) decreased from 8.14 +/- 0.7 to 0.48 +/- 0.1 ms at potentials between -40 and -150 mV. T channels inactivated by depolarization returned to the closed state along pathways that included two voltage-dependent time constants. tau rec-s ranged from 8.11 to 4.80 s when the recovery potential was varied from -50 to -90 mV, while tau rec-f decreased from 1.01 to 0.372 s. At potentials negative to -70 mV, both time constants approached minimum values. The low voltage-activated Ca2+ current in AZF cells was blocked by the T channel selective antagonist Ni2+ with an IC50 of 20 microM. At similar concentrations, Ni2+ also blocked cortisol secretion stimulated by adrenocorticotropic hormone. Our results indicate that bovine AZF cells are distinctive among secretory cells in expressing primarily or exclusively T-type Ca2+ channels.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Voltage-gated calcium channels in GtoPdb v.2021.2

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
William A. Catterall ◽  
Edward Perez-Reyes ◽  
Terrance P. Snutch ◽  
Jörg Striessnig
Keyword(s):  
High Voltage ◽  
Low Voltage ◽  
Transmembrane Domains ◽  
Voltage Gated ◽  
Voltage Dependent ◽  
Alternatively Spliced ◽  
Membrane Spanning ◽  
Voltage Gated Ion Channels ◽  
Ca2 Channels ◽  
Α1 Subunit

Calcium (Ca2+) channels are voltage-gated ion channels present in the membrane of most excitable cells. The nomenclature for Ca2+channels was proposed by [127] and approved by the NC-IUPHAR Subcommittee on Ca2+ channels [70]. Most Ca2+ channels form hetero-oligomeric complexes. The α1 subunit is pore-forming and provides the binding site(s) for practically all agonists and antagonists. The 10 cloned α1-subunits can be grouped into three families: (1) the high-voltage activated dihydropyridine-sensitive (L-type, CaV1.x) channels; (2) the high- to moderate-voltage activated dihydropyridine-insensitive (CaV2.x) channels and (3) the low-voltage-activated (T-type, CaV3.x) channels. Each α1 subunit has four homologous repeats (I-IV), each repeat having six transmembrane domains and a pore-forming region between transmembrane domains S5 and S6. Voltage-dependent gating is driven by the membrane spanning S4 segment, which contains highly conserved positive charges that respond to changes in membrane potential. All of the α1-subunit genes give rise to alternatively spliced products. At least for high-voltage activated channels, it is likely that native channels comprise co-assemblies of α1, β and α2-δ subunits. The γ subunits have not been proven to associate with channels other than the α1s skeletal muscle Cav1.1 channel. The α2-δ1 and α2-δ2 subunits bind gabapentin and pregabalin.

scholarly journals Voltage-gated calcium channels (CaV) in GtoPdb v.2021.3

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
William A. Catterall ◽  
Edward Perez-Reyes ◽  
Terrance P. Snutch ◽  
Jörg Striessnig
Keyword(s):  
High Voltage ◽  
Low Voltage ◽  
Excitable Cells ◽  
Voltage Gated ◽  
Voltage Dependent ◽  
Alternatively Spliced ◽  
Membrane Spanning ◽  
Voltage Gated Ion Channels ◽  
Ca2 Channels ◽  
Α1 Subunit

Ca2+ channels are voltage-gated ion channels present in the membrane of most excitable cells. The nomenclature for Ca2+channels was proposed by [127] and approved by the NC-IUPHAR Subcommittee on Ca2+ channels [70]. Most Ca2+ channels form hetero-oligomeric complexes. The α1 subunit is pore-forming and provides the binding site(s) for practically all agonists and antagonists. The 10 cloned α1-subunits can be grouped into three families: (1) the high-voltage activated dihydropyridine-sensitive (L-type, CaV1.x) channels; (2) the high- to moderate-voltage activated dihydropyridine-insensitive (CaV2.x) channels and (3) the low-voltage-activated (T-type, CaV3.x) channels. Each α1 subunit has four homologous repeats (I-IV), each repeat having six transmembrane domains (S1-S6) and a pore-forming region between S5 and S6. Voltage-dependent gating is driven by the membrane spanning S4 segment, which contains highly conserved positive charges that respond to changes in membrane potential. All of the α1-subunit genes give rise to alternatively spliced products. At least for high-voltage activated channels, it is likely that native channels comprise co-assemblies of α1, β and α2-δ subunits. The γ subunits have not been proven to associate with channels other than the α1s skeletal muscle Cav1.1 channel. The α2-δ1 and α2-δ2 subunits bind gabapentin and pregabalin.

Presenilin 1 Deficiency Alters the Activity of Voltage-Gated Ca2+ Channels in Cultured Cortical Neurons

2005 ◽  
Vol 94 (6) ◽  
pp. 4421-4429 ◽  
Author(s):  
David G. Cook ◽  
Xiaofan Li ◽  
Sheree D. Cherry ◽  
Angela R. Cantrell
Keyword(s):  
Cortical Neurons ◽  
Critical Role ◽  
Neuronal Firing ◽  
Voltage Gated ◽  
Voltage Dependent ◽  
Cultured Cortical Neurons ◽  
Intracellular Ca ◽  
Multiple Levels ◽  
P Type ◽  
Ca2 Channels

Presenilins 1 and 2 (PS1 and PS2, respectively) play a critical role in mediating γ-secretase cleavage of the amyloid precursor protein (APP). Numerous mutations in the presenilins are known to cause early-onset familial Alzheimer's disease (FAD). In addition, it is well established that PS1 deficiency leads to altered intracellular Ca2+ homeostasis involving endoplasmic reticulum Ca2+ stores. However, there has been little evidence suggesting Ca2+ signals from extracellular sources are influenced by PS1. Here we report that the Ca2+ currents carried by voltage-dependent Ca2+ channels are increased in PS1-deficient cortical neurons. This increase is mediated by a significant increase in the contributions of L- and P-type Ca2+ channels to the total voltage-mediated Ca2+ conductance in PS1 (−/−) neurons. In addition, chelating intracellular Ca2+ with 1,2-bis-( o-aminophenoxy)ethane- N,N,N′,N′-tetraacetic acid (BAPTA) produced an increase in Ca2+ current amplitude that was comparable to the increase caused by PS1 deficiency. In contrast to this, BAPTA had no effect on voltage-dependent Ca2+ conductances in PS1-deficient neurons. These data suggest that PS1 deficiency may influence voltage-gated Ca2+ channel function by means that involve intracellular Ca2+ signaling. These findings reveal that PS1 functions at multiple levels to regulate and stabilize intracellular Ca2+ levels that ultimately control neuronal firing behavior and influence synaptic transmission.

scholarly journals Voltage-gated calcium channels (version 2020.5) in the IUPHAR/BPS Guide to Pharmacology Database

2020 ◽  
Vol 2020 (5) ◽  
Author(s):  
William A. Catterall ◽  
Edward Perez-Reyes ◽  
Terrance P. Snutch ◽  
Jörg Striessnig
Keyword(s):  
High Voltage ◽  
Low Voltage ◽  
Transmembrane Domains ◽  
Voltage Gated ◽  
Voltage Dependent ◽  
Alternatively Spliced ◽  
Membrane Spanning ◽  
Voltage Gated Ion Channels ◽  
Ca2 Channels ◽  
Α1 Subunit

Calcium (Ca2+) channels are voltage-gated ion channels present in the membrane of most excitable cells. The nomenclature for Ca2+channels was proposed by [120] and approved by the NC-IUPHAR Subcommittee on Ca2+ channels [68]. Ca2+ channels form hetero-oligomeric complexes. The α1 subunit is pore-forming and provides the binding site(s) for practically all agonists and antagonists. The 10 cloned α1-subunits can be grouped into three families: (1) the high-voltage activated dihydropyridine-sensitive (L-type, CaV1.x) channels; (2) the high-voltage activated dihydropyridine-insensitive (CaV2.x) channels and (3) the low-voltage-activated (T-type, CaV3.x) channels. Each α1 subunit has four homologous repeats (I-IV), each repeat having six transmembrane domains and a pore-forming region between transmembrane domains S5 and S6. Voltage-dependent gating is driven by the membrane spanning S4 segment, which contains highly conserved positive charges that respond to changes in membrane potential. Many of the α1-subunit genes give rise to alternatively spliced products. At least for high-voltage activated channels, it is likely that native channels comprise co-assemblies of α1, β and α2-δ subunits. The γ subunits have not been proven to associate with channels other than the α1s skeletal muscle Cav1.1 channel. The α2-δ1 and α2-δ2 subunits bind gabapentin and pregabalin.

Inhibition of voltage-dependent Ca2+influx by extracellular ATP in salivary cells of the leech Haementeria ghilianii

1996 ◽  
Vol 199 (6) ◽  
pp. 1335-1341
Author(s):  
W Wuttke ◽  
T Munsch ◽  
J Deitmer
Keyword(s):  
Membrane Potential ◽  
Voltage Clamp ◽  
Extracellular Atp ◽  
Threshold Concentration ◽  
Resting Membrane Potential ◽  
Voltage Gated ◽  
Voltage Dependent ◽  
K Concentration ◽  
Gamma S ◽  
Ca2 Channels

The effects of extracellular ATP on intracellular free Ca2+ concentration ([Ca2+]i) and depolarization-induced elevations of [Ca2+]i were investigated in salivary cells of the leech Haementeria ghilianii using the fluorescent Ca2+ indicator Fura-2. Simultaneously, the membrane potential was monitored or controlled by voltage-clamp. The cell membrane was depolarized either by transient elevations of the extracellular K+ concentration ([K+]o) to 90 mmol l-1 or by depolarizing steps under voltage-clamp. The resulting transient elevations of [Ca2+]i (Ca2+ transients) could be repeatedly elicited with little variability in amplitude. Ca2+ transients were completely inhibited by 2 mmol l-1 Ni2+ or in Ca2+-free saline. The transients are, therefore, dependent on Ca2+ influx from the external medium through voltage-gated Ca2+ channels. The Ca2+ influx was rapidly and reversibly inhibited by extracellular application of ATP. The effect was dose-dependent with a threshold concentration below 10(-7) mol l-1. A 50 % reduction in the amplitude of Ca2+ transients was obtained by application of 1­2 µmol l-1 ATP or ATP-gamma-S (apparent IC50, 1.6 µmol l-1 ATP) and Ca2+ transients were almost completely inhibited by 30­100 µmol l-1 ATP. Resting [Ca2+]i, the resting membrane potential and membrane potential changes induced by 90 mmol l-1 [K+]o were not affected by ATP. Adenosine (10 µmol l-1) did not affect resting [Ca2+]i, the resting membrane potential or membrane potential changes induced by 90 mmol l-1 [K+]o and had little effect on Ca2+ transients. Suramin, an antagonist of vertebrate P2 receptors, was without effect on the inhibitory actions of ATP. We conclude that activation of a suramin-insensitive purinoceptor by ATP inhibits Ca2+ influx through voltage-gated Ca2+ channels in the salivary cells of Haementeria ghilianii.

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