Abstract
The pulmonary excretion rate of carbon monoxide (VeCO), an accepted index of bilirubin production, was measured in newborn rats with iatrogenic hematomas, and with tin-protoporphyrin, (TP) injected subcutaneously. TP, a synthetic metalloporphyrin has been shown in vitro and in vivo in the rat to competitively inhibit heme oxygenase, which is the rate-limiting enzyme in heme catabolism. TP treatment has also been associated with lower serum bilirubin levels in mutant mice with severe hemolytic anemia [Blood 61:1011, 1983].
Despite finding significant decreases in hepatic and splenic heme oxygenase activities after TP treatment, we did not find significant decreases in the mean VeCO and mean serum bilirubin levels of TP-treated rats with iatrogenic hematomas compared to nontreated rats with hematomas. Both groups had elevated bilirubin production and elevated bilirubin levels compared to saline-treated rats without hematomas. This suggests that 1) heme oxygenase activity may not directly reflect in vivo heme catabolism in this model; and 2) TP may not decrease heme catabolism, even when the latter is increased pathologically.
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Posselt, A., Ochikubo, C., Vreman, H. et al. THE EFFECT OF TIN-PROTOPORPHYRIN ON BILIRUBIN PRODUCTION IN NEWBORN RATS AFTER HEMATOMA FORMATION. Pediatr Res 18 (Suppl 4), 350 (1984). https://doi.org/10.1203/00006450-198404001-01541
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DOI: https://doi.org/10.1203/00006450-198404001-01541