Mun-Chual Rho, Norimichi Nakahata and Yasushi Ohizumi (*)
Department of Pharmaceutical Molecular Biology, Faculty of Pharmaceutical Sciences, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai 980, Japan
(*) To whom correspondence should be addressed.
Abstract: The marine toxin zooxanthellatoxin-A (ZT-A) and the Ca2+ ionophore ionomycin caused aggregation in rabbit platelets. While ZT-A-induced platelet aggregation was inhibited by indomethacin, ionomycin-induced aggregation was potentiated by the drug. In contrast, both ZT-A- and ionomycin-induced accumulations of thromboxane B2 (TXB2), a stable metabolite of thromboxane A2 (TXA2), were completely inhibited by indomethacin. 12S-Hydroxyeicosatetraenoic acid (12-HETE), which could be accumulated in the presence of indomethacin, inhibited ZT-A-induced aggregation, but it potentiated the ionomycin-induced one. These results suggest that the different effects of indomethacin may be attributed to the distinct effects of 12-HETE on ZT-A- and ionomycin-induced platelet aggregations.
Keywords: Zooxanthellatoxin-A, Ionomycin, 12S-Hydroxyeicosatetraenoic acid