Inactivation of Ca channels

Eckert, Roger; Chad, John E.

doi:10.1016/0079-6107(84)90009-9

Cited by 611 publications

(374 citation statements)

References 159 publications

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“…In addition to in a variety of invertebrate systems (Brehm and Eckert, 1978;Tillotson, 1979;Ashcroft and Stanfield, 1981;Eckert and Chad, 1984;Gutnick et al, 1989;Johnson and Byerly, 1993), Ca2+-dependent inactivation has been described for L-type Ca 2+ channels of mammalian cardiac muscle and neurohypophysis (Kass and Sanguinetti, 1984;Bechem and Pott, 1985;Kalman et al, 1988;Yue, Backx, and Imredy, 1990). Negative feedback control of Ca 2+ entry may be a common mechanism for the regulation of intracellular Ca z+ levels.…”

Section: Discussionmentioning

confidence: 99%

“…As with the N current described here, the HVA Ca 2+ current of molluscan neurons inactivates with both fast and slow components Eckert and Chad, 1984). Chad, Eckert and colleagues (Brehm and Eckert, 1978;Tillotson, 1979;Chad et al, 1984;Eckert and Chad, 1984) have demonstrated that the biphasic inactivation of this current is due to a CaZ+-dependent process.…”

Section: Properties Of N Current Inactivationmentioning

confidence: 99%

“…Chad, Eckert and colleagues (Brehm and Eckert, 1978;Tillotson, 1979;Chad et al, 1984;Eckert and Chad, 1984) have demonstrated that the biphasic inactivation of this current is due to a CaZ+-dependent process. They have further shown that the ratio of the rapid to slow phase of inactivation is reduced when the current is partially block with Cd 2+ .…”

Section: Properties Of N Current Inactivationmentioning

confidence: 99%

“…The experiment of Fig. 3 employs a variation on the classic two-pulse protocol used by previous investigators to test for the presence of current-dependent inactivation (Brehm and Eckert, 1978;Eckert and Chad, 1984;Kalman, O'Lague, Erxleben, and Armstrong, 1988;Kasai and Aosaki, 1988). In this experiment, a conditioning prepulse of varying amplitude and fixed duration is followed by a short test pulse to a potential that evokes maximal current.…”

Section: Inactivation As a Function Of Prepulse Potentialmentioning

confidence: 99%

“…neurons. The biphasic nature of inactivation in these neurons is most likely due to Ca2+-dependent inactivation of a single current type (Chad, Eckert, and Ewald, 1984;Eckert and Chad, 1984).…”

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confidence: 99%

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Inactivation of N-type calcium current in chick sensory neurons: calcium and voltage dependence.

Cox

Dunlap

1994

The Journal of General Physiology

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We have studied the inactivation of high-voltage-activated (HVA), t0-conotoxin-sensitive, N-type Ca 2+ current in embryonic chick dorsal root ganglion (DRG) neurons. Voltage steps from -80 to 0 mV produced inward Ca ~+ currents that inactivated in a biphasic manner and were fit well with the sum of two exponentials (with time constants of ~ 100 ms and > 1 s). As reported previously, upon depolarization of the holding potential to -40 mV, N current amplitude was significantly reduced and the rapid phase of inactivation all but eliminated (Nowycky, M. C., A. P. Fox, and R. W. be explained by a model in which N channels inactivate by both fast and slow voltage-dependent processes. Alternatively, kinetic models of Ca-dependent inactivation suggest that the biphasic kinetics and holding-potential-dependence of N current inactivation could be due to a combination of Ca-dependent and slow voltage-dependent inactivation mechanisms. To distinguish between these possibilities we have performed several experiments to test for the presence of Cadependent inactivation. Three lines of evidence suggest that N channels inactivate in a Ca-dependent manner. (a) The total extent of inactivation increased 50%, and the ratio of rapid to slow inactivation increased ~ twofold when the concentration of the Ca 2 § buffer, EGTA, in the patch pipette was reduced from 10 to 0.1 mM. (b) With low intracellular EGTA concentrations (0.1 mM), the ratio of rapid to slow inactivation was additionally increased when the extracellular Ca 2 § concentration was raised from 0.5 to 5 mM. (c) Substituting Na § for Ca 2 § as the permeant ion eliminated the rapid phase of inactivation. Other results do not support the notion of current-dependent inactivation, however. Although high intraceUular EGTA (10

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Section: Discussionmentioning

confidence: 99%

Section: Properties Of N Current Inactivationmentioning

confidence: 99%

Section: Properties Of N Current Inactivationmentioning

confidence: 99%

Section: Inactivation As a Function Of Prepulse Potentialmentioning

confidence: 99%

mentioning

confidence: 99%

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Inactivation of N-type calcium current in chick sensory neurons: calcium and voltage dependence.

Cox

Dunlap

1994

The Journal of General Physiology

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Conotoxin-sensitive and conotoxin-resistant Ca2+ currents in fish retinal ganglion cells

Bindokas

Ishida

1996

J. Neurobiol.

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Using whole‐cell patch‐clamp methods, we tested whether ω‐toxins from Conus block voltage‐gated Ca2+ currents in teleost central neurons. The fractions ω‐CTx‐GVIA and ω‐CTx‐MVIIC, together with ω‐toxins from Agelenopsis, the dihydropyridine BAY‐K‐8644, and voltage steps, produced effects indicating three types of Ca2+ current in dissociated goldfish retinal ganglion cells. One was activated by depolarization of most cells beyond −65 mV, primed at −95 mV but not at −45 mV, reduced by Ni2+, and unchanged by conotoxins, agatoxins, or BAY‐K‐8644. The second type constituted more than three‐quarters of the total Ca2+ current in all cells, and at test potentials more positive than −30 mV, was reduced consistently by ω‐CTx‐GVIA, ω‐CTx‐MVIIC, and ω‐Aga‐IA, but not ω‐Aga‐IVA. The third Ca2+ current type was augmented by BAY‐K‐8644 at test potentials as negative as −45 mV, even in the presence of ω‐CTx‐GVIA. Replacement of extracellular Ca2+ by Ba2+ augmented current amplitude and slowed current decay. Conditioning depolarizations reduced Ca2+ current amplitude less than did ω‐CTx‐GVIA, and slowed current decay to imperceptible rates. These results provide the first description of conotoxin‐sensitive, voltage‐gated Ca2+ current recorded from teleost central neurons. Although most of the high‐threshold Ca2+ current in these cells is blocked by ω‐CTx‐GVIA, it is also Ni2+‐sensitive, and relatively resistant to ω‐Aga‐IIIA. The voltage sensitivities of low‐ and high‐threshold Ca2+ current may suit current recruitment in situ after light‐evoked hyperpolarizations end, and after light‐evoked depolarizations begin, respectively. © 1996 John Wiley & Sons, Inc.

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Identified glial cells in the early postnatal mouse hippocampus display different types of Ca2+ currents

Akopian

Kressin

Derouiche

et al. 1996

Glia

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Inactivation of Ca channels

Cited by 611 publications

References 159 publications

Inactivation of N-type calcium current in chick sensory neurons: calcium and voltage dependence.

Inactivation of N-type calcium current in chick sensory neurons: calcium and voltage dependence.

Conotoxin-sensitive and conotoxin-resistant Ca2+ currents in fish retinal ganglion cells

Identified glial cells in the early postnatal mouse hippocampus display different types of Ca2+ currents

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