Barium modulates the gating of batrachotoxin-treated Na+ channels in high ionic strength solutions

Cukierman, Samuel

doi:10.1016/s0006-3495(93)81151-2

Cited by 5 publications

(3 citation statements)

References 19 publications

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“…The opening time-constant curve is shifted y100 mV, although the G(V ) curve is shifted only y6 mV (Elinder & Å rhem, 1994a). This discrepancy has been observed for many ion species (Shrager, 1974 ;Stanfield, 1975 ;Gilly & Armstrong, 1982a, b;Schauf, 1983 ;Armstrong & Matteson, 1986 ;Armstrong & Cota, 1990 ;Cukierman & Krueger, 1990Cukierman, 1993 ;Elinder & Å rhem, 1994a ;Terlau et al 1996 ;Tang et al 2000). The largest discrepancy is found for Zn 2+ and some of the lanthanides for the Kv channels (Stanfield, 1975 ;Gilly & Armstrong, 1982a, b;Armstrong & Cota, 1990 ;Elinder & Å rhem, 1994a), and for Mg 2+ on ether-à-go-go (eag) channels (Terlau et al 1996;Tang et al 2000).…”

Section: The Special Case Of Zn 2+ -No Binding In the Open Statementioning

confidence: 99%

Metal ion effects on ion channel gating

Elinder

Århem

2003

Quart. Rev. Biophys.

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Metal ions affect ion channels either by blocking the current or by modifying the gating. In the present review we analyse the effects on the gating of voltage-gated channels. We show that the effects can be understood in terms of three main mechanisms. Mechanism A assumes screening of fixed surface charges. Mechanism B assumes binding to fixed charges and an associated electrostatic modification of the voltage sensor. Mechanism C assumes binding and an associated non electrostatic modification of the gating. To quantify the non-electrostatic effect we introduced a slowing factor, A. A fourth mechanism (D) is binding to the pore with a consequent pore block, and could be a special case of Mechanisms B or C. A further classification considers whether the metal ion affects a single site or multiple sites. Analysing the properties of these mechanisms and the vast number of studies of metal ion effects on different voltage-gated on channels we conclude that group 2 ions mainly affect channels by classical screening (a version of Mechanism A). The transition metals and the Zn group ions mainly bind to the channel and electrostatically modify the gating (Mechanism B), causing larger shifts of the steady-state parameters than the group 2 ions, but also different shifts of activation and deactivation curves. The lanthanides mainly bind to the channel and both electrostatically and non-electrostatically modify the gating (Mechanisms B and C). With the exception of the ether-à-go-go-like channels, most channel types show remarkably similar ion-specific sensitivities.

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Section: The Special Case Of Zn 2+ -No Binding In the Open Statementioning

confidence: 99%

Metal ion effects on ion channel gating

Elinder

Århem

2003

Quart. Rev. Biophys.

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“…Ba 2+ may also inhibit K + channels [56] and, by blocking the repolarizing action of K + channels, facilitate membrane depolarization [40]. Ba 2+ can stimulate the release of Ca 2+ from intracellular sites, block Ca 2+ extrusion from the cytosol [57,58], and modify the gating kinetics of Na + channels [59].…”

Section: Discussionmentioning

confidence: 99%

Probing Nanoelectroporation and Resealing of the Cell Membrane by the Entry of Ca2+ and Ba2+ Ions

Šilkūnas

Mangalanathan

et al. 2020

IJMS

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The principal bioeffect of the nanosecond pulsed electric field (nsPEF) is a lasting cell membrane permeabilization, which is often attributed to the formation of nanometer-sized pores. Such pores may be too small for detection by the uptake of fluorescent dyes. We tested if Ca2+, Cd2+, Zn2+, and Ba2+ ions can be used as nanoporation markers. Time-lapse imaging was performed in CHO, BPAE, and HEK cells loaded with Fluo-4, Calbryte, or Fluo-8 dyes. Ca2+ and Ba2+ did not change fluorescence in intact cells, whereas their entry after nsPEF increased fluorescence within <1 ms. The threshold for one 300-ns pulse was at 1.5–2 kV/cm, much lower than >7 kV/cm for the formation of larger pores that admitted YO-PRO-1, TO-PRO-3, or propidium dye into the cells. Ba2+ entry caused a gradual emission rise, which reached a stable level in 2 min or, with more intense nsPEF, kept rising steadily for at least 30 min. Ca2+ entry could elicit calcium-induced calcium release (CICR) followed by Ca2+ removal from the cytosol, which markedly affected the time course, polarity, amplitude, and the dose-dependence of fluorescence change. Both Ca2+ and Ba2+ proved as sensitive nanoporation markers, with Ba2+ being more reliable for monitoring membrane damage and resealing.

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“…For example, in ceils which could be studied with a microelectrode [1,2], the relative conductances for various cations first helped characterize plasma membrane calcium channels [3,4], and the gating of voltage-activated so,dim channels was affected by divalent barium ion [5]. Fluorescent indicators have been widely used in cells which are too small for the microelectrode and these have shown, for example, agonist-activated M n 2+ entry in both platelets [6] and lymphocytes [7].…”

Section: Introductionmentioning

confidence: 99%

Indo-1 can simultaneously detect Ba2+ entry and Ca2+ blockade at a plasma membrane calcium channel

Owen

Dever

1995

Mol Cell Biochem

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The fluorescent chelator Indo-1 can make simultaneous determinations of two intracellular ion concentrations, such as [Ca2+] and [Cd2+], or [Ca2+] and [Ba2+], in a normal cell suspension. The second ion can be detected even if its spectrum when bound to Indo-1 is same as for the calcium-bound or the ion-free Indo-1, as long as there is a change in height. This is because the mathematical analysis uses not only the spectral shape, but also takes into account increases in total signal intensity. For maximum accuracy, whole spectra were analyzed. When 3 mM [Ba2+] was added to a B cell line that had been stimulated with antiimmunoglobulin to open receptor operated calcium channels, there was a sudden drop in 400 nm Indo-1 fluorescence. Spectral analysis showed that this was due to a drop in intracellular [Ca2+], which was consistent with blockage of the receptor-operated calcium current by extracellular Ba2+. The conductance for Ba2+ was also observable as a slow rise in total fluorescence. There was also a slow increase in intracellular [Ca2+] as barium accumulated in the cell, which was tentatively attributed to blockage of the plasma membrane calcium pump by intracellular Ba2+.

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Barium modulates the gating of batrachotoxin-treated Na+ channels in high ionic strength solutions

Cited by 5 publications

References 19 publications

Metal ion effects on ion channel gating

Metal ion effects on ion channel gating

Probing Nanoelectroporation and Resealing of the Cell Membrane by the Entry of Ca2+ and Ba2+ Ions

Indo-1 can simultaneously detect Ba2+ entry and Ca2+ blockade at a plasma membrane calcium channel

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