Kinetics of the sodium current through EDTA-modified calcium channels of the molluscan neuron somatic membrane

1984 ◽  
Vol 15 (5) ◽  
pp. 401-407
Author(s):  
Ya. M. Shuba
Keyword(s):  
Calcium Channels ◽  
Sodium Current ◽  
Somatic Membrane ◽  
Molluscan Neuron ◽  
Kinetics Of

Kinetics of voltage-dependent sodium current in cultured frog Schwann cells

1991 ◽  
Vol 16 ◽  
pp. 1
Author(s):  
Takefumi Miyazaki ◽  
Junko Tasaka ◽  
Saeko Sakai ◽  
Toshio Hashiguchi ◽  
Tsuneo Tosaka
Keyword(s):  
Schwann Cells ◽  
Sodium Current ◽  
Voltage Dependent ◽  
Kinetics Of

Alterations of voltage-activated sodium current by a novel conotoxin from the venom of Conus gloriamaris

1995 ◽  
Vol 73 (3) ◽  
pp. 1295-1301 ◽  
Author(s):  
A. Hasson ◽  
K. J. Shon ◽  
B. M. Olivera ◽  
M. E. Spira
Keyword(s):  
Steady State ◽  
Action Potential ◽  
Sodium Current ◽  
Land Snails ◽  
Calcium Currents ◽  
Inactivation Kinetics ◽  
The Novel ◽  
Inactivation Curve ◽  
Aplysia Neurons ◽  
Kinetics Of

1. The novel peptide toxin delta-conotoxin-GmVIA, recently purified by us from the mollusk-hunting snail Conus gloriamaris, induces convulsive-like contractions when injected into land snails but has no detectable effects in mammals. 2. At concentrations of 0.5-0.75 microM, the toxin induces action potential broadening and increased excitability of cultured Aplysia neurons. 3. Whole cell patch-clamp experiments on cultured Aplysia neurons revealed that the toxin does not alter potassium or calcium currents, but induces action potential broadening by slowing the inactivation kinetics of the sodium current. Under control conditions, the inactivation kinetics of the sodium current follows a single exponential with tau = 0.47 +/- 0.14 (SE) ms. After toxin application the sodium current inactivation is composed of two phases: an early phase with tau = 0.86 +/- 0.12 ms and a late phase of slowly inactivating sodium current with tau = 488 +/- 120 ms. In addition, the toxin shifts the voltage-dependent steady-state inactivation curve to more positive values and the steady-state activation curve to more negative values. These alterations are not associated with changes in the rise time or the peak value of the sodium current. 4. The novel delta-conotoxin-GmVIA, and the previously described "King Kong peptide," purified from another mollusk-hunting cone (Conus textile), share a similar cystein framework also found in the calcium channel blocking peptide omega-conotoxin but represent a new class of conotoxins with unusual specificity for molluscan sodium channels.

scholarly journals Amino acid substitutions in the FXYD motif enhance phospholemman-induced modulation of cardiac L-type calcium channels

2010 ◽  
Vol 299 (5) ◽  
pp. C1203-C1211 ◽  
Author(s):  
Kai Guo ◽  
Xianming Wang ◽  
Guofeng Gao ◽  
Congxin Huang ◽  
Keith S. Elmslie ◽  
...  
Keyword(s):  
Amino Acid ◽  
Calcium Channels ◽  
Molecular Mechanisms ◽  
Channel Gating ◽  
Fine Tuning ◽  
Amino Acid Substitutions ◽  
Dependent Inactivation ◽  
Voltage Dependent ◽  
Kinetics Of

We have found that phospholemman (PLM) associates with and modulates the gating of cardiac L-type calcium channels (Wang et al., Biophys J 98: 1149–1159, 2010). The short 17 amino acid extracellular NH2-terminal domain of PLM contains a highly conserved PFTYD sequence that defines it as a member of the FXYD family of ion transport regulators. Although we have learned a great deal about PLM-dependent changes in calcium channel gating, little is known regarding the molecular mechanisms underlying the observed changes. Therefore, we investigated the role of the PFTYD segment in the modulation of cardiac calcium channels by individually replacing Pro-8, Phe-9, Thr-10, Tyr-11, and Asp-12 with alanine (P8A, F9A, T10A, Y11A, D12A). In addition, Asp-12 was changed to lysine (D12K) and cysteine (D12C). As expected, wild-type PLM significantly slows channel activation and deactivation and enhances voltage-dependent inactivation (VDI). We were surprised to find that amino acid substitutions at Thr-10 and Asp-12 significantly enhanced the ability of PLM to modulate CaV1.2 gating. T10A exhibited a twofold enhancement of PLM-induced slowing of activation, whereas D12K and D12C dramatically enhanced PLM-induced increase of VDI. The PLM-induced slowing of channel closing was abrogated by D12A and D12C, whereas D12K and T10A failed to impact this effect. These studies demonstrate that the PFXYD motif is not necessary for the association of PLM with CaV1.2. Instead, since altering the chemical and/or physical properties of the PFXYD segment alters the relative magnitudes of opposing PLM-induced effects on CaV1.2 channel gating, PLM appears to play an important role in fine tuning the gating kinetics of cardiac calcium channels and likely plays an important role in shaping the cardiac action potential and regulating Ca2+ dynamics in the heart.

scholarly journals Sodium current kinetics of transitional myocytes in Koch triangle of rabbit hearts

2008 ◽  
Vol 121 (21) ◽  
pp. 2185-2191 ◽  
Author(s):  
Fu-xian REN ◽  
Xiao-lin NIU ◽  
Yan OU ◽  
Song-mei XIE ◽  
Feng-dong LING ◽  
...  
Keyword(s):  
Sodium Current ◽  
Kinetics Of
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