Metabolism of arachidonic acid by isolated rabbit ciliary epithelium.

We examined the ability of rabbit ciliary epithelium to metabolize arachidonic acid in vitro. The epithelium was homogenized and incubated with 14C-labeled arachidonic acid. 14C-labeled metabolites were extracted and then separated by thin layer chromatography. The range of arachidonic acid metabolites synthesized by ciliary epithelium was compared to the metabolites generated by rabbit iris-ciliary body. Ciliary epithelium produced substantial amounts of arachidonic acid metabolites that comigrated with 5-HETE and 12-HETE. Authenticity of the 12-HETE produced by ciliary epithelium was confirmed by gas chromatography/mass spectrometry. The ciliary epithelium generated only small amounts of the cyclooxygenase products, PGF2 alpha, PGE2, PGD2 and 6k-PGF1 alpha. In contrast, the iris-ciliary body produced large amounts of cyclooxygenase products such as PGF2 alpha and PGD2. The ability of the ciliary epithelium to generate 12-HETE is noteworthy since 12(R)-HETE is known to be capable of lowering intraocular pressure.