Characterization of platelet-activating factor-induced cytosolic calcium mobilization in human eosinophils

T. Oshiro, Y. Kakuta, S. Shimura, M. Nara, Kunio Shirato

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


Background: Activated eosinophils play an important role in the pathogenesis of bronchial asthma and other allergic diseases, and platelet- activating factor (PAF) is a potent activator of eosinophils. Objective: To characterize the cytosolic Ca2+ [Ca2+](i) mobilization in human eosinophils in response to PAF. Methods: [Ca2+](i) responses to PAF were examined in human eosinophils using a microscopic fura-2 fluorescence-ratio imaging system. Results: PAF caused a significant and dose-dependent increase in (Ca2+)(i), which consisted of an initial rapid rise followed by a sustained elevation. This PAF-induced (Ca2+)(i) rise was inhibited by WEB 2086, a specific PAF receptor antagonist. The addition of 5 mM EGTA or 1 mM Ni2+ to a nominally Ca2+-free solution did not appreciably reduce the initial rise but significantly inhibited the sustained rise. The application of a protein kinase C inhibitor, Ro31-8220, augmented the sustained increase by PAF. Thapsigargin, a microsomal Ca2+ ATPase inhibitor, induced no appreciable change in a nominally Ca2+-free solution but induced a marked increase in (Ca2+)(i) when changed to a Ca2+-containing solution. Conclusions: The initial rapid rise and the following sustained rise in (Ca2+)(i) by PAF depends on Ca2+ release from the intracellular Ca2+ stores and Ca2+ influx, respectively, which are regulated by protein kinase C in human eosinophils. Furthermore, the so called Ca2+-capacitative entry is possibly involved in the Ca2+ influx from the extracellular solution in human eosinophils.

Original languageEnglish
Pages (from-to)699-705
Number of pages7
JournalClinical and Experimental Allergy
Issue number5
Publication statusPublished - 2000
Externally publishedYes


  • Ca-capacitative entry
  • Cytosolic-free calcium
  • Human eosinophils
  • Platelet-activating factor
  • Protein kinase C
  • Thapsigargin

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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