title: Enhancement of collagen-induced phosphoinositide turnover by thromboxane A2 analogue through Ca2+ mobilization in human platelets.
abstract: In human washed platelets, collagen-induced phosphoinositide turnover was inhibited by indomethacin, an inhibitor of thromboxane A2 (TXA2) formation, particularly at lower doses of collagen. This inhibition was counteracted by the addition of 9,11-epithio-11,12-methano-TXA2 (STA2), a stable analogue of TXA2 as well as by the Ca2+ ionophore A23187. STA2 and A23187 did not stimulate phosphoinositide turnover markedly, but significantly increased cytoplasmic free Ca2+ concentrations. The actions of STA2 were blocked by 13-azaprostanoic acid, a TXA2 receptor antagonist. The results suggest that TXA2 is generated during the action of collagen and increases cytoplasmic free Ca2+ which then stimulates phosphoinositide turnover in cooperation with collagen.
mesh_terms: D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000097:blood*; D003094:Collagen / Q000494:pharmacology*; D003593:Cytoplasm / Q000378:metabolism; D006801:Humans; D007213:Indomethacin / Q000494:pharmacology; D009218:Myosins / Q000097:blood; D010712:Phosphatidic Acids / Q000097:blood; D010716:Phosphatidylinositols / Q000097:blood*; D010766:Phosphorylation; D011466:Prostanoic Acids / Q000494:pharmacology; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000097:blood* / Q000494:pharmacology
chemical_list: D010712:Phosphatidic Acids; D010716:Phosphatidylinositols; D011466:Prostanoic Acids; D000001:Calcimycin; D013928:Thromboxane A2; C022574:13-azaprostanoic acid; C037866:STA 2; D003094:Collagen; D009218:Myosins; D002118:Calcium; D007213:Indomethacin