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Characterization of platelet‐activating factor‐induced elevation of cytosolic free calcium concentration in eosinophils
Author(s) -
Kroegel Claus,
Pleass Robert,
Yukawa Tatsuo,
Chung K.Fan,
Westwick John,
Barnes Peter J.
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)81214-1
Subject(s) - platelet activating factor , egta , calcium , chemistry , antagonist , degranulation , fura 2 , endocrinology , guinea pig , medicine , cytosol , biophysics , biochemistry , receptor , biology , enzyme , organic chemistry
In order to evaluate the role of calcium in the activation processes in eosinophils induced by platelet‐activating factor (PAF), we investigated the changes in free cytoplasmatic Ca 2+ concentration using fura‐2. PAF causes a rapid and transitory rise of the intracellular free calcium ion concentration ([Ca 2+ ] i ) in purified guinea pig eosinophils of approx. 1000 nM above a basal level of 120.7 ± 36.5 nM ( n = 10). The effect was dose‐related with a maximum rise at 1000 nM PAF and an EC 50 of 17.4 nM and specifically inhibited by the PAF antagonist WEB 2086 with an IC 50 , of 95.5 nM. WEB 2086 did not affect either the leukotriene B 4 ‐ or the fMet‐Leu‐Phe‐induced elevation of [C 2+ ] i . The response to PAF was dependent on external Ca 2+ as it was significantly inhibited by EGTA (85.6 ± 5.4%) and Ni 2+ (95.8 ± 2.1 %) but not by the dihydropyridine antagonist nimodipine. We conclude that Ca 2+ entry via receptor‐operated Ca 2+ channels may be involved in PAF‐induced degranulation of eosinophils.