Characterization of platelet-activating factor-induced elevation of cytosolic free calcium concentration in eosinophils

• Published in: FEBS letters 1989-01, Vol.243 (1), p.41-46
• Main Authors: Kroegel, Claus, Pleass, Robert, Yukawa, Tatsuo, Chung, K.Fan, Westwick, John, Barnes, Peter J.
• Format: Article
• Language: English
• Subjects: Animals; Azepines - pharmacology; Ca 2+ concentration, intracellular; Ca2+ concentration, intracellular; Calcium - blood; Cytosol - drug effects; Cytosol - metabolism; Eosinophils - drug effects; Eosinophils - metabolism; Guinea Pigs; In Vitro Techniques; Kinetics; Male; Platelet Activating Factor - analogs & derivatives; Platelet Activating Factor - pharmacology; Platelet-activating factor; Platelet-activating factor antagonist WEB 2086; Reference Values; Triazines - pharmacology; Triazoles
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(89)81214-1

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.