Thromboxane Formation from Arachidonic Acid and Prostaglandin H₂ in Rabbit Spleen

Abstract

Incubation of [1-¹⁴C]arachidonic acid (AA) and [1-¹⁴C]prostaglandin (PG)H₂ with rabbit spleen homogenate and microsomes resulted in the formation of a substance with the chromatographic properties of thromboxane (Tx)B₂. The radiolabeled material was indistinguishable from authentic TxB₂ on TLC in three solvent systems and on radiometric gas chromatography. The generation of TxB₂-like material from AA and PGH₂ was not observed after boiling of the homogenate and microsomes, and was completely inhibited by imidazole (5mM). The transformation of AA into the TxB₂-like material was not observed during incubation in the presence of indomethacin (28 μm). These results indicate that TxB₂ is the principal product of arachidonic acid metabolism by the homogenate or microsomes of rabbit spleen.