Heme oxygenase induction by heme analogues.
(A) For heme oxygenase mRNA Northern analysis, confluent human umbilical vein endothelial cells cultured in 10-cm tissue-culture dishes were incubated with medium 199 alone (first lane), 10 μmol/L hematin (second lane), 10 μmol/L heme arginate (third lane), 10 μmol/L iron deuteroporphyrin IX,2,4-bis-sulfonate (fourth lane), 10 μmol/L iron coproporphyrin III (fifth lane), 10 μmol/L iron deuteroporphyrin IX,2,4-bis-glycol (sixth lane), or 10 μmol/L iron deuteroporphyrin IX (seventh lane) in media 199 for 60 minutes followed by an additional 4 hours' incubation with hematin and heme analogue-free medium. RNA was isolated, electrophoresed, blotted, and hybridized with a 32P-labeled heme oxygenase cDNA probe. (B) Densitometry tracings of heme oxygenase mRNA bands expressed as arbitrary OD units. (C) The corresponding 28S and 18S ribosomal RNA of the Northern blot in (A). (D) Heme oxygenase enzyme activity (picomolar of bilirubin formed per milligram of cell protein per 60 minutes) measured at 8 hours after exposure of endothelial cell monolayers to the same compounds as above. Results represent the enzyme activity (mean ± SE) of at least 3 experiments done in duplicate.
