Exposure of endothelial cells to iron deuteroporphyrin IX, hematin, heme arginate, and other substances.

Iron deuteroporphyrin IX, like hematin, but unlike heme arginate, iron deuteroporphyrin IX,2,4-bis-sulfonate, iron coproporphyrin III, or iron deuteroporphyrin IX,2,4-bis-glycol, sensitized endothelial cells to H₂O₂ and activated PMN-mediated cytolysis. Confluent ⁵¹Cr-labeled human umbilical vein endothelial cells grown in 24-well (2 cm²/well) tissue-culture plates were incubated with medium 199 alone (first bars), 5 μmol/L hematin (second bars), 5 μmol/L heme arginate (third bars), 5 μmol/L iron deuteroporphyrin IX,2,4-bis-sulfonate (fourth bars), 5 μmol/L iron coproporphyrin III (fifth bars), 5 μmol/L iron deuteroporphyrin IX,2,4-bis-glycol (sixth bars), or 5 μmol/l iron deuteroporphyrin IX (seventh bars) in 500 μL of media 199 for 60 minutes. After removal of solutions, the cells were washed with HBSS and exposed for 2 hours to (A) 100 μmol/L H₂O₂or (B) PMA (100 ng/mL–activated neutrophils (2:1 PMN:endothelial cell ratio). Results represent the percentage of specific cytotoxicity (mean ± SE) of at least 3 experiments performed in duplicate.