Prostaglandin and thromboxane synthesis by microsomes of rabbit ocular tissues

Microsomes of albino rabbit ocular tissues were incubated with (1-¹⁴C)-arachidonic acid for 15 min at 37° C. Thin-layer chromatography revealed that ciliary body-iris microsomes were capable of synthesizing prostaglandin F₂α, PGF₂α, PGE₂, PGD₂, thromboxane B₂ (TXB₂), and 6-keto-PGF₁α. Indomethacin 14 μM in the incubation medium essentially abolished all prostaglandin synthesis detectable by this method. Imidazole 10 mM in the incubation medium inhibited only TXB₂ synthesis. Ciliary body-iris microsomes were incubated for 2 min at 0° C with PGH₂. The products of this reaction were superfused over spiral strips of rabbit aorta and produced the strong contractions typical of TXA₂. Addition of imidazole to the incubation medium blocked the formation of the contracting substance. Incubation of ciliary body-iris microsomes with (1-¹⁴C)-8,11,14-eicosatrienoic acid produced PGF₁α, PGD₁ and PGE₁ but no evidence of any thromboxane product or 6-keto-PGF₁α. Conjunctival and corneal microsomes syntesized prostaglandins, although less effectively than ciliary body-iris microsomes, when incubated with (1-¹⁴C)-arachidonic acid. Microsomes of sclera, retina-choroid, and lens synthesized little, if any prostaglandins.