Solvent substitution as a probe of channel gating in Myxicola. Effects of D2O on kinetic properties of drugs that occlude channels

Schauf, C. L.; Bullock, J.O.

doi:10.1016/s0006-3495(82)84690-0

Cited by 24 publications

(26 citation statements)

References 35 publications

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“…The fast components of these traces now overlie with no apparent dissimilarities in their rates. However, we also noticed (as did Schauf and Bullock [1982] from Myxicola) that when…”

Section: Resultssupporting

confidence: 56%

“…Schauf and Bullock (1982) also reported that the sodium channel tail current was apparently insensitive to the solvent effects. They noticed that when the tail current records in H20 and D20 were scaled and superimposed, the fast components were identical while the slower components showed slight sensitivity or variability in D20.…”

Section: Resultsmentioning

confidence: 96%

“…Furthermore the channel activation gates must be exposed to a hydrophilic phase and hence affected by D20, whereas the principle gating solvent substitution. On the other hand, Schauf and Bullock (1982) also observe that closure (deactivation) of conducting sodium channels is insensitive to the effects of D20. The rate constants of the fast and slow components of sodium tail current remain unaltered during solvent substitution.…”

Section: Introductionmentioning

confidence: 94%

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Sodium channel activation mechanisms. Insights from deuterium oxide substitution

Alicata¹,

Rayner²,

Starkus³

1990

Biophysical Journal

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Schauf and Bullock (1979. Biophys. J. 27:193-208; 1982. Biophys. J. 37:441-452), using Myxicola giant axons, demonstrated that solvent substitution with deuterium oxide (D2O) significantly affects both sodium channel activation and inactivation kinetics without corresponding changes in gating current or tail current rates. They concluded that (a) no significant component of gating current derives from the final channel opening step, and (b) channels must deactivate (during tail currents) by a different pathway from that used in channel opening. By contrast, Oxford (1981. J. Gen. Physiol. 77:1-22) found in squid axons that when a depolarizing pulse is interrupted by a brief (approximately 100 microseconds) return to holding potential, subsequent reactivation (secondary activation) is very rapid and shows almost monoexponential kinetics. Increasing the interpulse interval resulted in secondary activation rate returning towards control, sigmoid (primary activation) kinetics. He concluded that channels open and close (deactivate) via the same pathway. We have repeated both sets of observations in crayfish axons, confirming the results obtained in both previous studies, despite the apparently contradictory conclusions reached by these authors. On the other hand, we find that secondary activation after a brief interpulse interval (50 microseconds) is insensitive to D2O, although reactivation after longer interpulse intervals (approximately 400 microseconds) returns towards a D2O sensitivity similar to that of primary activation. We conclude that D2O-sensitive primary activation and D2O-insensitive tail current deactivation involve separate pathways. However, D2O-insensitive secondary activation involves reversal of the D2O-insensitive deactivation step. These conclusions are consistent with "parallel gate" models, provided that one gating particle has a substantially reduced effective valence.

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“…The fast components of these traces now overlie with no apparent dissimilarities in their rates. However, we also noticed (as did Schauf and Bullock [1982] from Myxicola) that when…”

Section: Resultssupporting

confidence: 56%

Section: Resultsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 94%

See 1 more Smart Citation

Sodium channel activation mechanisms. Insights from deuterium oxide substitution

Alicata¹,

Rayner²,

Starkus³

1990

Biophysical Journal

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“…As was described previously, the H/D ratio in conductance of Na + is 1.35 (Schauf & Bullock, 1982). Different from other ionic currents, when the Na + channel is abruptly depolarized, a small outward current precedes the Na + current.…”

Section: Na + Channelsupporting

confidence: 53%

Functional Difference Between Deuterated and Protonated Macromolecules

Sugiyama¹,

Yoshioka²

2012

Protein Structure

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“…For example, voltage-dependent Na channels of rabbit muscle activate 2.3 times faster and inactivate 3.4–9.1 times faster upon a 10°C temperature increase in the range of 0 to 22°C [22]. Within a similar temperature range, the rates of Myxicola axon voltage-dependent K channel activation and inactivation were estimated to be 2.4 and 3.0 times, respectively, faster [30]. Assuming similar Q 10 values for the rat hippocampal neuron voltage-dependent Na and K channels, we expect their activities to increase by 52–202% (for Na channel) and 55–73% (for K channel) upon 500 ms irradiation of the CNI-laser used in this study.…”

Section: Discussionmentioning

confidence: 99%

Temperature-dependent Activation of Neurons by Continuous Near-infrared Laser

Liang

Yang

Zhou

et al. 2008

Cell Biochem Biophys

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Optical control of neuronal activity has a number of advantages over electrical methods and can be conveniently applied to intact individual neurons in vivo. In this study, we demonstrated an experimental approach in which a focused continuous near-infrared (CNI) laser beam was used to activate single rat hippocampal neurons by transiently elevating the local temperature. Reversible changes in the amplitude and kinetics of neuronal voltage-gated Na and K channel currents were recorded following irradiation with a single-mode 980 nm CNI-laser. Using single-channel recordings under controlled temperatures as a means of calibration, it was estimated that temperature at the neuron rose by 14°C in 500 ms. Computer simulation confirmed that small temperature changes of about 5°C were sufficient to produce significant changes in neuronal excitability. The method should be broadly applicable to studies of neuronal activity under physiological conditions, in particular studies of temperature-sensing neurons expressing thermoTRP channels.

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Solvent substitution as a probe of channel gating in Myxicola. Effects of D2O on kinetic properties of drugs that occlude channels

Cited by 24 publications

References 35 publications

Sodium channel activation mechanisms. Insights from deuterium oxide substitution

Sodium channel activation mechanisms. Insights from deuterium oxide substitution

Functional Difference Between Deuterated and Protonated Macromolecules

Temperature-dependent Activation of Neurons by Continuous Near-infrared Laser

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