Activation of Ca2+-dependent K+ channels in human B lymphocytes by anti-immunoglobulin.

MacDougall, Stephen L.; Grinstein, Sergio; Gelfand, Erwin W.

doi:10.1172/jci113340

Cited by 67 publications

(38 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Cells were added to the cuvette at a final concentration of 2 ϫ 10 6 cells/ml. Fluorescence was calibrated using ionomycin and Mn 2ϩ as described previously (15,16,22) using a dissociation constant of 250 nM (23).…”

Section: Methodsmentioning

confidence: 99%

Evidence for a Phorbol Ester-insensitive Phosphorylation Step in Capacitative Calcium Entry in Rat Thymic Lymphocytes

Marriott

Mason

1996

Journal of Biological Chemistry

View full text Add to dashboard Cite

Section: Methodsmentioning

confidence: 99%

Evidence for a Phorbol Ester-insensitive Phosphorylation Step in Capacitative Calcium Entry in Rat Thymic Lymphocytes

Marriott

Mason

1996

Journal of Biological Chemistry

View full text Add to dashboard Cite

“…Although Ca 2+ entry across the plasma membrane would be expected to depolarize the cell, several studies of human T and B cells and mouse thymocytes have shown instead that membrane hyperpolarization accompanies the rise in [Ca2+]i (Tsien et al, 1982;Felber and Brand, 1983;Wilson and Chused, 1985;Tatham, O'Flynn, and Linch, 1986;MacDougall, Grinstein, and Gelfand, 1988; reviewed by Grinstein and Dixon, 1989). Preliminary fluorescent-indicator studies on individual cells indicate that oscillations in membrane potential accompany the [Ca2+]i oscillations in Jurkat T cells (Lewis, Grissmer, and Cahalan, 1991).…”

Section: Introductionmentioning

confidence: 99%

Calcium-activated potassium channels in resting and activated human T lymphocytes. Expression levels, calcium dependence, ion selectivity, and pharmacology.

Grissmer

Nguyen

Cahalan

1993

The Journal of General Physiology

206

143

View full text Add to dashboard Cite

Ca2+-activated K+[K(Ca)] channels in resting and activated human peripheral blood T lymphocytes were characterized using simultaneous patch-clamp recording and fura-2 monitoring of cytosolic Ca 2+ concentration, [Ca2+]i . Whole-cell experiments, using EGTA-buffered pipette solutions to raise [CaZ÷]i to 1 p,M, revealed a 25-fold increase in the number of conducting K(Ca) channels per cell, from an average of 20 in resting T cells to > 500 channels per cell in T cell blasts after mitogenic activation. The opening of K(Ca) channels in both whole-cell and inside-out patch experiments was highly sensitive to [Ca2+]i (Hill coefficient of 4, with a midpoint of ~ 300 nM). At optimal [Ca2+]i, the open probability of a K(Ca) channel was 0.3-0.5. K(Ca) channels showed little or no voltage dependence from -100 to 0 inV. Single-channel/-V curves were linear with a unitary conductance of 11 pS in normal Ringer and exhibited modest inward rectification with a unitary conductance of ~35 pS in symmetrical 160 mM K ÷. Permeability ratios, relative to K +, determined from reversal potential measurements were: K + (1.0) > Rb + (0.96) > NH~" (0.17) > Cs ÷ (0.07). Slope conductance ratios were: NH~ (1.2) > K + (1.0) > Rb + (0.6) > Cs ÷ (0.10). Extracellular Cs + or Ba 2+ each induced voltagedependent block of K(Ca) channels, with block increasing at hyperpolarizing potentials in a manner suggesting a site of block 75% across the membrane field from the outside. K(Ca) channels were blocked by tetraethylammonium (TEA) applied externally (Kd = 40 mM), but were unaffected by 10 mM TEA applied inside by pipette perfusion. K(Ca) channels were blocked by charybdotoxin (CTX) with a half-blocking dose of 3-4 nM, but were resistant to block by noxiustoxin (NTX) at 1-100 nM. Unlike K(Ca) channels in Jurkat T cells, the K(Ca) channels of normal resting or activated T cells were not blocked by apamin. We conclude that while K(Ca) and voltage-gated K + channels in the same cells share similarities in ion

show abstract

“…The first is a release of Ca" from intracellular stores mediated by an increase in intracellular inositol 1,4,5 trisphosphate (IP,); (Bijsterbosch et al, 1986;Monroe and Cambier, 1983). The second component is due to the entry of extracellular Ca2+ across the plasma membrane as evidenced by its dependence upon availability of extracellular Ca2+ (Bijsterbosch et al, 1986;MacDougall et al, 1988a). The net result of these mechanisms is a biphasic rise in [Ca"], with a transient peak due to release from stores subsiding to a lower sustained plateau phase maintained by influx of Ca2' from the extracellular medium.…”

mentioning

confidence: 99%

Role of intracellular Ca²⁺ stores in the regulation of electrogenic plasma membrane Ca²⁺ uptake in a B‐lymphocytic cell line

Marriott

Bost

Mason

1994

Journal Cellular Physiology

View full text Add to dashboard Cite

Experiments were undertaken to investigate the role of intracellular Ca2+ stores in the regulation of Ca2+ uptake in the cultured B-lymphocytic cell line CH12.LX.C4.5F5. Release of intracellular Ca2+ stores by addition of thapsigargin was accompanied by a biphasic increase in intracellular calcium concentration [Ca2+]i). The initial rise in [Ca2+]i was due to release of Ca2+ from intracellular stores as determined by its maintenance in the absence of extracellular Ca2+. The secondary phase was 1) dependent on the presence of extracellular Ca2+, 2) inhibited by 5 mM extracellular Ni2+, and 3) inhibited by high K+, consistent with electrogenic Ca2+ uptake from the extracellular medium. In order to more accurately investigate the electrogenic nature of this pathway we measured the membrane potential changes accompanying Ca2+ influx stimulated by release of Ca2+ from intracellular stores using bis(1,3-diethylthiobarbituric acid trimethine) oxonol in Bapta-loaded cells. Addition of 5 mM Ca2+ to cells pretreated with doses of thapsigargin or ionomycin shown to release intracellular Ca2+ stores induced a depolarization which was 1) dependent upon extracellular Ca2+, 2) abolished by 5 mM Ni2+, 3) independent of extracellular Na+, and 4) dependent upon Bapta loading. This depolarization was followed by a charybdotoxin-sensitive repolarization consistent with secondary activation of K+ channels. Changes in [Ca2+]i monitored under identical conditions were monitored fluorimetrically using indo-1 and were found to correlate with the changes in Em. On the basis of these data we conclude that an electrogenic Ca(2+)-permeable pathway exists in this B-lymphocytic cell line which is regulated by the degree of filling of an internal Ca(2+)-store.

show abstract

Activation of Ca2+-dependent K+ channels in human B lymphocytes by anti-immunoglobulin.

Cited by 67 publications

References 27 publications

Evidence for a Phorbol Ester-insensitive Phosphorylation Step in Capacitative Calcium Entry in Rat Thymic Lymphocytes

Evidence for a Phorbol Ester-insensitive Phosphorylation Step in Capacitative Calcium Entry in Rat Thymic Lymphocytes

Calcium-activated potassium channels in resting and activated human T lymphocytes. Expression levels, calcium dependence, ion selectivity, and pharmacology.

Role of intracellular Ca²⁺ stores in the regulation of electrogenic plasma membrane Ca²⁺ uptake in a B‐lymphocytic cell line

Contact Info

Product

Resources

About

Activation of Ca2+-dependent K+ channels in human B lymphocytes by anti-immunoglobulin.

Cited by 67 publications

References 27 publications

Evidence for a Phorbol Ester-insensitive Phosphorylation Step in Capacitative Calcium Entry in Rat Thymic Lymphocytes

Evidence for a Phorbol Ester-insensitive Phosphorylation Step in Capacitative Calcium Entry in Rat Thymic Lymphocytes

Calcium-activated potassium channels in resting and activated human T lymphocytes. Expression levels, calcium dependence, ion selectivity, and pharmacology.

Role of intracellular Ca2+ stores in the regulation of electrogenic plasma membrane Ca2+ uptake in a B‐lymphocytic cell line

Contact Info

Product

Resources

About

Role of intracellular Ca²⁺ stores in the regulation of electrogenic plasma membrane Ca²⁺ uptake in a B‐lymphocytic cell line