Which prostanoid metabolites should be determined for the study of reproductive processes?

Abstract

The non-enzymatic metabolites of prostacyclin (PGI 2) and thromboxane A 2 (TXA 2), 6-keto-prostaglandin F 1α (6-keto-PGF 1α) and thromboxane B 2 (TXB 2), and their 2,3-dinor metabolites, 2,3-dinor-6-keto-PGF 1α and 2,3-dinor-TXB 2, were measured in early morning urine samples in 24 in vitro fertilization (IVF) cycles in 24 women and in 27 women who became pregnant after IVF and embryo transfer (ET). The sum of the non-enzymatic metabolites and their 2,3-dinor metabolites was considered to be a reflection of total PGI 2 and total TXA 2 production in vivo. Both the ratio of ‘total’ PGI 2/‘total’ TXA 2 and the ratio of the 2,3-dinor metabolites were calculated. TXB 2 concentrations showed virtually no change and the ratios of the non-enzymatic metabolites of PGI 2 and TXA 2 versus their 2,3-dinor metabolites remained relatively constant. As a consequence, the ratio of 2,3-dinor-6-keto-PGF 1α/2,3-dinor-TXB 2 was a close reflection of the ratio of ‘total’ PGI 2/‘total’ TXA 2, although the latter ratio was significantly higher all the time. We conclude that for comparative studies on the balance between PGI 2 and TXA 2 in IVF cycles and during gestation, the determination of the 2,3-dinor metabolites alone can replace the measurement of all four metabolites.