Activation of Ca2+ current in Jurkat T cells following the depletion of Ca2+ stores by microsomal Ca2+-ATPase inhibitors

Brett A. Premack, Thomas V. McDonald, Phyllis Gardner

Research output: Contribution to journalArticle

127 Citations (Scopus)

Abstract

The mechanism of TCR-stimulated Ca2+ influx was studied in the jurkat human T cell line using Ca2+ indicator dyes and whole-cell patch clamp. Ca2+ influx induced by inositol 1,4,5-triphosphate (IP3)-coupled surface receptors (either the TCR or a heterologous muscarinic receptor) was compared with Ca2+ influx induced by inhibitors of the microsomal Ca2+-ATPase (thapsigargin, cyclopiazonic acid, di-tert-butylhydroquinone), which release stored Ca2+ without production of IP3. The same Ca2+ influx pathway could be activated by IP3-dependent or IP3-independent means, and therefore appeared to be regulated by the fullness of the microsomal Ca2+ stores rather than by the direct action of IP3. Depletion of stored Ca2+ by either receptor stimulation or microsomal Ca2+-ATPaSe inhibition activated a low conductance, Ca2+-selective, non-voltage-activated membrane current. Ca2+ currents induced by receptor stimulation and Ca2+-ATPaSe inhibition were not additive. Several properties of the depletion-activated Ca2+ current suggest that it is carried by a novel type of Ca2+ channel rather than an electrogenic carrier or pump. The conductance saturated when external Ca2+ was raised (Kd ≈2 mM) and became highly permeable to monovalent cations when external Ca2+ was lowered to below 100 nM, much as has been observed for some voltage-gated Ca2+ channels. The Ca2+ current was reversibly blocked by >90% with 0.3 mM Cd2+, whereas the same concentration of Ni2+ or Co2+ blocked only 50 to 60% of the current. However, the absence of voltage-dependent activation, relative conductance sequence for divalent cations (Ca2+>Ba2+≈Sr2+≫Mn2+), and lack of inhibition by nifedipine, D600, diltiazem, δ-conotoxin, or aga-IVa were unlike that of voltage-gated Ca2+ channels.

Original languageEnglish (US)
Pages (from-to)5226-5240
Number of pages15
JournalJournal of Immunology
Volume152
Issue number11
StatePublished - Jun 1 1994
Externally publishedYes

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Conotoxins
Gallopamil
Monovalent Cations
Inositol 1,4,5-Trisphosphate
Jurkat Cells
Thapsigargin
Calcium-Transporting ATPases
Diltiazem
Divalent Cations
Muscarinic Receptors
Nifedipine
Coloring Agents
T-Lymphocytes
Cell Line
Membranes
2-tert-butylhydroquinone
cyclopiazonic acid

ASJC Scopus subject areas

  • Immunology

Cite this

Activation of Ca2+ current in Jurkat T cells following the depletion of Ca2+ stores by microsomal Ca2+-ATPase inhibitors. / Premack, Brett A.; McDonald, Thomas V.; Gardner, Phyllis.

In: Journal of Immunology, Vol. 152, No. 11, 01.06.1994, p. 5226-5240.

Research output: Contribution to journalArticle

Premack, Brett A. ; McDonald, Thomas V. ; Gardner, Phyllis. / Activation of Ca2+ current in Jurkat T cells following the depletion of Ca2+ stores by microsomal Ca2+-ATPase inhibitors. In: Journal of Immunology. 1994 ; Vol. 152, No. 11. pp. 5226-5240.
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