Bradykinin-stimulated prostaglandin synthesis in conscious rabbits

1 Bradykinin was infused intravenously into conscious rabbits to determine its effect on the concentration of prostaglandins in plasma. 6-Oxo-prostaglandin (PG) F1 alpha, the stable hydrolysis product of prostacyclin, and 13,14-dihydro-15-oxo-PGF2 alpha, a metabolite derived from PGE2 and PGF2 alpha, were measured by gas chromatography-electron capture mass spectrometry. 2 Incremental infusions of bradykinin (0.4-3.2 micrograms kg-1 min-1) increased plasma concentrations of both 6-oxo-PGF1 alpha and 13,14-dihydro-15-oxo-PGF2 alpha. 3 Aspirin (10 mg kg-1, i.v.) inhibited bradykinin-stimulated 6-oxo-PGF1 alpha and 13,14-dihydro-15-oxo-PGF2 alpha synthesis at 30 min and 6 h. At 24 h, the mean bradykinin-stimulated 13,14-dihydro-15-oxo-PGF2 alpha concentration was 66% of its original value, whilst 6-oxo-PGF1 alpha remained substantially inhibited. 4 The different rates of recovery of bradykinin-stimulated production of the two prostaglandins after inhibition by aspirin suggests that intravenous bradykinin stimulates prostacyclin and PGE2/PGF2 alpha production in distinct cell populations which synthesize cyclo-oxygenase at different rates.