Origin of intracellular calcium and quantitation of mobilizable calcium in neutrophils stimulated with chemotactic peptide

Takafumi Hamachi, Masato Hirata, Toshitaka Koga

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17 Citations (Scopus)


The origin and amount of mobilized Ca2+ in chemotactic peptide-stimulated guinea pig neutrophils were examined using biochemical techniques. The total amount of releasable Ca2+ by 20 μM A23187 from the unstimulated intact cells was 0.91 nmol 4·106 cells, as assessed by change in absorbance of the antipyrylazo III-Ca2+ complex. Two types of internal vesicular Ca2+ pool, mitochondrial and non-mitochondrial pool were identified in the saponin-permeabilized cells. The total amount of releasable Ca2+ was comparable to that accumulated by the non-mitochondrial pool at (1-2)·10-7 M of a free Ca2+ concentration. The mitochondrial uncoupler, capable of releasing Ca2+ from the mitochondrial pool, neither modified the basal cytosolic free Ca2+ in quin 2-loaded cells nor caused a Ca2+ efflux from the intact cells. These results suggest that the releasable Ca2+ may be located in the non-mitochondrial pool of unstimulated intact cells, and the mitochondrial pool contains little releasable Ca2+. The addition of fMet-Leu-Phe increased the cytosolic free Ca2+ by two processes: Ca2+ mobilization from internal stores and Ca2+ influx through the surface membrane. The Ca2+ mobilized and effluxed from the intact cells by stimulation with the maximal doses of fMet-Leu-Phe was estimated to be 0.27 nmol 4·106 cells. Almost equal amounts were released by the maximal doses of inositol 1,4,5-trisphosphate from the non-mitochondrial pool of saponin-treated cells that had accumulated Ca2+ at a free Ca2+ concentration of 1.4·10-7 M. The mechanism related to the Ca2+ influx by fMet-Leu-Phe stimulation was also examined. The addition of nifedipine or phosphatidic acid did not affect the change in the cytosolic free Ca2+ induced by fMet-Leu-Phe, thereby suggesting that the receptor-mediated Ca2+ channel may be involved in the Ca2+ influx.

Original languageEnglish
Pages (from-to)136-148
Number of pages13
JournalBBA - Molecular Cell Research
Issue number2
Publication statusPublished - Nov 28 1986

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology


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