ENDOGENOUS REACTIVE OXYGEN METABOLITES MEDIATE SUBLETHAL ENDOTHELIAL-CELL DYSFUNCTION DURING REOXYGENATION

Purpose: Endothelial cells (EC) secrete vasoactive eicosanoids, which maintain organ blood flow. Because EC are a major source of eicosanoid s, we studied the effects of reoxygenation on EC prostacyclin producti on. Methods: Bovine aortic EC cultures were exposed to 2 hours of norm oxia, then 1 hour of hypoxia (PO2 = 10 +/- 3.5 mm Hg), followed by 1.5 hours of reoxygenation in either normal medium or medium plus either superoxide dismutase (SOD, 300 units/ml), catalase (1200 units/ml), al lopurinol (5.0 x 10(-4) mol/L), or dinitrophenol (10(-4) mol/L). Resul ts: Prostacyclin production decreased to 40% (p < 0.05) of basal prost acyclin production after 1 hour of hypoxia. EC reoxygenated with contr ol medium recovered to 48% of basal prostacyclin production. EC reoxyg enated in SOD resulted in recovery (p < 0.05) to 154% of basal prostac yclin production after 60 minutes. Catalase treatment resulted in reco very to 105% (p < 0.05) of basal prostacyclin production within 30 min utes of reoxygenation. Allopurinol treatment resulted in 77% recovery (p < 0.05) of basal prostacyclin production only during 30 minutes of reoxygenation. Dinitrophenol treatment resulted in significant (greate r than or equal to 85%, P < 0.05) sustained recovery of basal prostacy clin production at 30, 60, and 90 minutes of experimental reperfusion. Conclusions: The hypoxia-induced decrease in EC prostacyclin does not recover during reoxygenation. Catalase/SOD allowed return to baseline prostacyclin production during reoxygenation, implicating reactive ox ygen metabolites as mediators of decreased eicosanoid biosynthesis. Re covery of prostacyclin production after 60 minutes reoxygenation with dinitrophenol but not allopurinol suggests a mitochondrial origin of t he oxygen metabolites responsible for decreased prostacyclin biosynthe sis.