Calcium channels in PDGF-stimulated A172 cells open after intracellular calcium release and are not voltage-dependent

J. Szöllösi, Burt G.F. Feuerstein, G. Vereb, H. A. Pershadsingh, L. J. Marton

Research output: Contribution to journalArticle

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Abstract

Using laser image cytometry and indo-1 fluorescence, we investigated the intracellular free Ca2+ concentration ([Ca2+]i) of confluent A172 human glioblastoma cells stimulated by the BB homodimer of platelet-derived growth factor (PDGF-BB). The shape of the calcium transients and the delay time between stimulation and the beginning of the transient varied considerably. The percentage of responsive cells, the peak [Ca2+]i and the duration of the response were directly related to PDGF-BB dose, while the delay time was inversely related; the maximal response occurred at a PDGF-BB concentration of 20 ng/ml. Studies with EGTA and inorganic calcium-channel blockers (Ni2+, La3+) showed that the increase of [Ca2+]i resulted from initial release of intracellular stores and subsequent calcium influx across the plasma membrane. Opening of calcium channels in the plasma membrane, monitored directly by studying Mn2+ quenching of indo-1 fluorescence, was stimulated by PDGF-BB and blocked by La3+; the opening occurred 55 ± 10 s after the initial increase in [Ca2+]i. Therefore, in these tumor cells, intracellular release always occurs before channel opening in the plasma membrane. Depolarization of cells with high extracellular [K+] did not generally induce calcium transients but did decrease calcium influx. L-type calcium-channel blockers (verapamil, nifedipine, and diltiazem) had little or no effect on the calcium influx induced by PDGF-BB. These results indicate that PDGF-BB induces calcium influx by a mechanism independent of voltage-sensitive calcium channels in A172 human glioblastoma cells.

Original languageEnglish (US)
Pages (from-to)477-491
Number of pages15
JournalCell Calcium
Volume12
Issue number7
DOIs
StatePublished - 1991
Externally publishedYes

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Calcium Channels
Calcium
Cell Membrane
Calcium Channel Blockers
Glioblastoma
Fluorescence
Image Cytometry
L-Type Calcium Channels
Diltiazem
Egtazic Acid
Nifedipine
Verapamil
platelet-derived growth factor BB
Lasers
Neoplasms

ASJC Scopus subject areas

  • Cell Biology
  • Endocrinology

Cite this

Calcium channels in PDGF-stimulated A172 cells open after intracellular calcium release and are not voltage-dependent. / Szöllösi, J.; Feuerstein, Burt G.F.; Vereb, G.; Pershadsingh, H. A.; Marton, L. J.

In: Cell Calcium, Vol. 12, No. 7, 1991, p. 477-491.

Research output: Contribution to journalArticle

Szöllösi, J. ; Feuerstein, Burt G.F. ; Vereb, G. ; Pershadsingh, H. A. ; Marton, L. J. / Calcium channels in PDGF-stimulated A172 cells open after intracellular calcium release and are not voltage-dependent. In: Cell Calcium. 1991 ; Vol. 12, No. 7. pp. 477-491.
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