Elevation of cytoplasmic free calcium concentration by stable thromboxane A2 analogue in human platelets.
9, 11-Epithio-11, 12-methano-thromboxane A2 (STA2), a stable analogue of thromboxane A2, caused a rapid rise in cytoplasmic free Ca2+ concentration ([Ca2+]i) in human platelets as measured with the fluorescent Ca2+ indicator quin2. Concomitantly, this compound induced phosphorylation of myosin light chain which is catalyzed by Ca2+, calmodulin-dependent protein kinase. These reactions were fast enough to trigger serotonin release. 13-Azaprostanoic acid, a receptor level antagonist of thromboxane A2 inhibited STA2-induced elevation of [Ca2+]i, phosphorylation of myosin light chain and serotonin release. These results provide evidence that STA2 interacts with a thromboxane A2 receptor which leads to elevation of [Ca2+]i.
D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000097:blood*; D003593:Cytoplasm / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D010766:Phosphorylation; D011982:Receptors, Prostaglandin / Q000187:drug effects; D017482:Receptors, Thromboxane; D012701:Serotonin / Q000097:blood; D013050:Spectrometry, Fluorescence; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000494:pharmacology*; D013931:Thromboxanes / Q000494:pharmacology*
D011982:Receptors, Prostaglandin; D017482:Receptors, Thromboxane; D013931:Thromboxanes; D012701:Serotonin; D013928:Thromboxane A2; C037866:STA 2; D002118:Calcium