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Enhancement of collagen‐induced phosphoinositide turnover by thromboxane A 2 analogue through Ca 2+ mobilization in human platelets
Author(s) -
Kaibuchi Kozo,
Tsuda Terutaka,
Kikuchi Akira,
Tanimoto Tetsuji,
Takai Yoshimi
Publication year - 1985
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(85)80052-1
Subject(s) - platelet , chemistry , thromboxane a2 , thromboxane , ionophore , antagonist , endocrinology , cytoplasm , medicine , collagen receptor , receptor , biochemistry , biology , membrane , integrin
In human washed platelets, collagen‐induced phosphoinositide turnover was inhibited by indomethacin, an inhibitor of thromboxane A 2 (TXA 2 ) formation, particularly at lower doses of collagen. This inhibition was counteracted by the addition of 9,11‐epithio‐11,12‐methano‐TXA 2 (STA 2 ), a stable analogue of TXA 2 as well as by the Ca 2+ ionophore A23187. STA 2 and A23187 did not stimulate phosphoinositide turnover markedly, but significantly increased cytoplasmic free Ca 2+ concentrations. The actions of STA 2 were blocked by 13‐azaprostanoic acid, a TXA 2 receptor antagonist. These results suggest that TXA 2 is generated during the action of collagen and increases cytoplasmic free Ca 2+ which then stimulates phosphoinositide turnover in cooperation with collagen.