H₂O₂-Induced Platelet Aggregation and Increase in Intracellular Ca²⁺ Concentration Are Blocked by Inhibitors of Intracellular Signaling

E. N. Loiko^1*, A. B. Samal¹, and S. M. Shulyakovskaya²

¹Department of Biophysics, Belarusian State University, pr. F. Skoriny 4, Minsk 220050, Belarus; fax: (017) 209-5445; E-mail: Loiko@bsu.by

²Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, ul. Akad. Kuprevicha 5/2, Minsk 220141, Belarus; fax: (017) 263-7274; E-mail: eseniya@iboch.bas-net.by

^* To whom correspondence should be addressed.

Received June 14, 2002; Revision received November 12, 2002

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Inhibitors of signaling enzymes such as guanosine-5´-O-2-thiodiphosphate, aristolochic acid, aspirin, indomethacin, and trifluoperazine block H₂O₂-induced platelet aggregation and H₂O₂-induced increase in the intracellular concentration of Ca²⁺. These findings suggest that the effect of H₂O₂ on platelets is associated with activation of signal pathways responsible for increase in the concentration of intracellular Ca²⁺. On H₂O₂-induced platelet aggregation, the concentration of cAMP in the cytoplasm decreases and that of cGMP increases.

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KEY WORDS: hydrogen peroxide, platelets, platelet aggregation, intracellular Ca²⁺, cAMP, cGMP, inhibitors, ADP, arachidonic acid

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