Effects of prolonged hypoxia, reoxygenation, and shear stress on bovine aortic endothelial cell prostacyclin production

Bovine aortic endothelial cell prostacyclin production was assessed under conditions of shear stress, hypoxia, and reoxygenation. Methods: Endothelial cell cultures (n = 8) grown on microcarrier beads were sequentially exposed to 2 h of normoxia (O₂ = 20%), then 24 h of hypoxia (O₂ = 2%) and 2 h of reoxygenation (O₂ = 20%). Cell viability, levels of prostaglandin H₂ synthase protein, and prostacyclin production were evaluated. Results: Prostacyclin production decreased significantly after 1 h of hypoxia, and became undetectable after 24 h. Reoxygenation did not result in recovery of normoxic levels of prostacyclin production. Immunoblots revealed no change in the levels of prostaglandin H₂ synthase protein during hypoxia, and reoxygenation. Addition of arachidonic acid to cells (n = 5) during reoxygenation resulted in prompt recovery of prostacyclin synthesis. Conclusions: Endothelial cells exposed to sequential conditions of hypoxia and reoxygenation in the presence of shear stress decreased prostacyclin production. The decrease in prostacyclin production was not due to altered cell viability, levels of prostaglandin H₂ synthase, or inactivation of prostaglandin H₂ synthase.