11-dehydro Thromboxane B2 EIA Kit

库存 ：大量

供应商 ：广州威佳科技有限公司

规格 ：96 wells 、480 wells

Limit of detection: 80% B/B0: 16 pg/ml · Sensitivity: 50% B/B0: 93 pg/ml · Thromboxane A2 (TXA2) is produced from arachidonic acid by many cells and causes irreversible platelet aggregation and vascular and bronchial smooth muscle contraction.1,2,3 TXA2 is rapidly hydrolyzed non-enzymatically to form TXB2. Although it is common to estimate TXA2 levels by measuring TXB2, most of the TXB2 measured in plasma or urine is due to ex vivo platelet activation or intra-renal production, respectively.4 Measurement errors are compounded by the fact that normal concentrations of circulating TXB2 are extremely low (1-2 pg/ml), and highly transient (t½ = 5-7 minutes).5,6 To circumvent this problem, it is necessary to measure a metabolite that cannot be formed by platelets or by the kidney. TXB2 can be metabolized by 11-hydroxy thromboxane dehydrogenase to form 11-dehydro TXB2, or by β-oxidation to form 2,3-dinor TXB2.7 Infusion studies using TXB2 have shown that both metabolites are formed equally, although 11-dehydro TXB2 has a longer circulating half-life (t½ = 45 minutes).6,8 Therefore, measurement of 11-dehydro TXB2 in plasma or urine will give a time-integrated indication of TXA2 production. Normal plasma levels of 11-dehydro TXB2 (1-2 pg/ml) are below the detection limit of this assay (10 pg/ml), so plasma samples must be purified and concentrated prior to analysis.9 Because urine contains many possible crossreacting eicosanoid metabolites, it is prudent to purify urine also. This assay has been validated by comparison to GC/MS.10

1 Hamberg, M., Svensson, J., Samuelsson, B. Thromboxanes: A new group of biologically active compounds derived from prostaglandin endoperoxides. Proc Natl Acad Sci USA 72 2994-2998 (1975). 2 Ellis, E.F., Oelz, O., Roberts, L.J., et al. Coronary arterial smooth muscle contraction by a substance released from platelets: Evidence that it is thromboxane A2. Science 193 1135-1137 (1976). 3 Salzman, P.M., Salmon, J.A., Moncada, S. Prostacyclin and thromboxane A2 synthesis by rabbit pulmonary artery. J Pharmacol Exp Ther 215 240-247 (1980). 4 Samuelsson, B., Granström, E., Green, K., et al. Prostaglandins. Annu Rev Biochem 44 669-695 (1975). 5 Patrono, C., Ciabattoni, G., Pugliese, F., et al. Estimated rate of thromboxane secretion into the circulation of normal humans. J Clin Invest 77 590-594 (1986). 6 Lawson, J.A., Patrono, C., Ciabattoni, G., et al. Long-lived enzymatic metabolites of thromboxane B2 in the human circulation. Anal Biochem 155 198-205 (1986). 7 Roberts, L.J., Sweetman, B.J., Oates, J.A. Metabolism of thromboxane B2 in man. J Biol Chem 256(16) 8384-8393 (1981). 8 Ciabattoni, G., Pugliese, F., Davi, G., et al. Fractional conversion of thromboxane B2 to urinary 11-dehydrothromboxane B2 in man. Biochim Biophys Acta 992 66-70 (1989). 9 Catella, F., Healy, D., Lawson, J.A., et al. 11-dehydro Thromboxane B2: A quantitative index of thromboxane A2 formation in the human circulation. Proc Natl Acad Sci USA 83 5861-5865 (1986). 10 Lellouche, F., Fradin, A., FitzGerald, G., et al. Enzyme immunoassay measurement of the urinary metabolites of thromboxane A2 and prostacyclin. Prostaglandins 40 297-310 (1990).