Abstract
After CS2 administration a slight loss of heme was demonstrated from the microsomal fraction of rat liver, and when the microsomal heme was prelabeled with 5-amino[4-14C]levulinate, a loss of heme radioactivity from the microsomes was observed after CS2 treatment with accumulation of heme radioactivity in the cell sap. The conversion in vivo of 5-amino[4-14C]levulinate into bile bilirubin and the activity of liver heme oxygenase were both stimulated by CS2 treatment. Phenobarbital pretreatment of the rats, prior to CS2 administration, potentiated the stimulation of heme oxygenase caused by CS2, whereas cycloheximide pretreatment completely prevented it. A stimulation of liver heme oxygenase was also found after administration of diethylphenylphosphorothionate, pentothal, and phenylthiourea, whereas the oxygen-containing analogues of the last two drugs were inactive. It is concluded that the accelerated liver heme conversion to bile pigments caused by CS2, pentothal, and other sulfur-containing drugs is related to their metabolism by oxidative desulfuration and ensuing microsomal toxicity: the damage of the apoprotein of cytochrome P-450 may result in a reduced affinity for heme, with more liver heme being available for degradation.
ACKNOWLEDGMENTS We thank Dr. W. N. Aldridge for providing a sample of diethylphenylphosphorothionate.
- Copyright © 1978 by Academic Press, Inc.
MolPharm articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|