Arachidonate metabolism in bovine gallbladder mucosa

Incubation of [1-14C] arachidonicacid (AA) with homogenates of bovine gallbladder mucosa in the presence or absence of reduced glutathione (GSH) generated large amounts of products that cochromatographed with PGE2 and 6-keto-PGF1 alpha and small amounts of products comigrating with PGF2 alpha, TxB2 and PGD2. In the presence of GSH PGE2-like material was predominantly produced while in the absence of GSH 6-keto-PGF1 alpha-like material was a major product. Identification of PGE2 was performed by its chemical conversion with NaBH4 or KOH treatments and by gas chromatography-mass spectrometry. Identification of 6-keto-PGF1 alpha was confirmed by gas chromatography-mass spectrometry. Gallbladder muscle produced predominantly 6-keto-PGF1 alpha in the presence or absence of GSH. The total amount of cyclooxygenase products was approximately 2 times higher in the mucosa than in the muscle. These results indicate that bovine gallbladder mucosa contains higher levels of fatty acid cyclooxygenase, and PGE2 isomerase and PGI2 synthetase in a proportion different from that in the muscle.