Measurement of prostaglandin D2 and identification of metabolites in human plasma during intravenous infusion.

A stable isotope dilution assay has been developed for the quantification of prostaglandin D2 (PGD2) in plasma. Samples are analysed by capillary column gas chromatography/negative ion chemical ionisation mass spectrometry (GC/NICIMS). The method employs an internal standard of [2H6]PGD2, prepared biosynthetically by incubation of rat peritoneal mast cells with deuterated arachidonic acid. No PGD2 was detected in peripheral venous plasma samples obtained from 10 healthy male volunteers (detection limit = 5 pg ml-1). Following intravenous infusion of PGD2 at increasing incremental infusion rates ranging from 16-256 ng kg-1 min-1, a dose related increase in the plasma concentration of PGD2 was observed. Plasma levels at 128 ng kg-1 min-1 ranged from 724-1444 pg ml-1. The major circulating metabolites of PGD2, during infusion, were identified as 13,14-dihydro-15-oxo-PGF2 alpha and 15-oxo-PGF2 alpha.