Production of thromboxane and prostaglandins in human blood in the presence of thromboxane synthase inhibitors

Abstract

The radioimmunological determination (RIA) of primary prostaglandins (PGs) in serum and plasma was evaluated with gas chromatography / mass spectrometry (GC/MS). Human blood was stimulated in vitro in the presence or absence of the specific thromboxane synthase inhibitor ridogrel. TxB2, 6-keto-PGFlα, PGE2, PGD2 and PGF2α were determined with RIA and GC/MS on the same samples. For GC/MS analysis, prostanoids were extracted and derivatized to their methoximepentafluorobenzyl-esrers-trimethylsilyl-ethers. An excellent correlation was observed between levels of all eicosanoids determined by RIA or GC/MS (r = 0.996–0.999) when plasma was spiked with known amounts of PGs and TxB2 (2 - 500 ng/ml). In stimulated blood, with or without inhibition of thromboxane synthase, the correlation between RIA and GC/MS values remained good, except for 6-keto-PGFlα. RIA largely overestimated the levels of 6-keto-PGFlα and no significant correlation was found with levels detected by GC/MS. The results demonstrate the importance of corroboraring the reliability of RIA with GC/MS.