The possible biological importance of lipoxygenase pathway in aorta endothelial cells.

Cultured calf aortic endothelial cells metabolize exogenous 1-[14C] arachidonic acid via the lipoxygenase pathway to 12-hydroxyeicosatetraenoic acid and dihydroxyeicosatetraenoic acid(s). Disruption of the cells by freezing and thawing strongly increases the formation of lipoxygenase metabolites. Under these conditions mainly 15-hydroxy-eicosatetraenoic acid was formed in addition to 12-hydroxyeicosatetraenoic acid. From the calculation of the specific radioactivity of the lipoxygenase products formed it was concluded that not only the exogenous but also endogenous arachidonic acid released from intracellular sources such as phospholipids, triglycerides or cholesterol esters is oxygenated. The possible biological significance of the lipoxygenase metabolites is discussed.