Phospholipid fatty acid composition of pulmonary airway epithelial cells: potential substrates for oxygenation.

To determine possible substrates for airway epithelial lipoxygenase and cyclooxygenase activities, we examined the amounts and distributions of fatty acids in phospholipids of human, dog and sheep airway epithelial cells. We found that the cells contained significant levels of n-6 and n-3 fatty acids in species-specific amounts: dog cells were relatively enriched in the n-6 series and poor in n-3, while sheep cells were enriched in the n-3 series and poor in n-6. Despite differences in fatty acid content, cells from each species expressed a constant phospholipid composition and distributed their n-6 and n-3 fatty acids in a stereotyped fashion among phospholipid classes. The analysis shows that the species differences in oxygenation activities reported previously are paralleled by heterogeneity in potential substrates.