Thromboxane plasma measurement

For prediction of likely in vivo activity, inhibition of ADP or U-46619 (a stable thromboxane A2 mimetic) induced platelet aggregation has been measured in citrated whole blood. The extent of aggregation is determined using a single platelet counter [33, 35, 38], Compounds may be less potent in the whole blood assay than in the partially purified platelet assays described above if the drug is significantly bound to plasma proteins. 

Ogletree, M.L., Begley, C.J., King, G.A. and Brigham, K.L. (1986). Influence of steroidal and nonsteroidal anti-inflammatory agents on the accumulation of arachidonic acid metabolites in plasma and lung lymph after endotoxemia in awake sheep. Measurements of prostacyclin and thromboxane metabolites and 12-HETE. Am. Rev. Respir. Dis., 133, 55-61... 

Two clinical studies have demonstrated that aspirin reduces the incidence of myocardial infarction and death by up to 50% in patients with unstable angina, suggesting an important role for thromboxane A2 in their occur-rence . Whether platelet activation and thromboxane A2 also play a role in the episodic ischaemia of unstable angina is unknown. Evidence of platelet activation " in patients with unstable angina based on plasma levels of platelet granule proteins, such as j8-thromboglobulin and platelet factor 4, is difficult to interpret since such measurements are highly sensitive to ex vivo platelet activation . Similarly, studies of thromboxane A2 biosynthesis have been... 

Both PASs and Biomer solutions (10%) were poured individually into glass tubes, and the insides of the glass tubes (7-mm ID X 50 mm) were coated, the solvent was then evaporated under vacuum at 60°C for 48 h. One milliliter of human whole blood was poured into the tubes and allowed to stand for 7 min. After centrifuging (4000 rpm, 30 min), 300 jxL samples of separated plasma were collected and thromboxane B2 (TXB ) concentrations were measured by radioimmunoassay (RIA) [44,45]. 

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