title: In vivo protection by protein A of hepatic microsomal mixed function oxygenase system of cyclophosphamide-treated rats.
abstract: At a high dose, cyclophosphamide (Cy, 200 mg/kg) causes depression of the enzyme activity of the hepatic mixed function oxygenase (MFO) system in Sprague-Dawley rats. The present report provides evidence for the early regeneration of the depleted enzyme activity in Cy-treated rats by purified protein A (P) of Staphylococcus aureus. Enzymes of the MFO system, such as aminopyrine demethylase and aryl hydrocarbon hydroxylase, were assayed and the content of cytochrome P-450 was determined. Inoculation of P (60 micrograms/kg) prior to Cy inoculation provides a better effect than P administration after Cy. The exact mechanism of P action is unknown. P-treated animals appear to have an ability to repair the damage caused by the toxic metabolites of Cy earlier than those in the Cy group. This property of protein A may become useful in accelerated regeneration of the enzyme activity in the hepatic MFO system following the toxic insult of Cy metabolites.
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism; D003520:Cyclophosphamide / Q000494:pharmacology*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004347:Drug Interactions; D005260:Female; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013205:Staphylococcal Protein A / Q000494:pharmacology*
chemical_list: D013205:Staphylococcal Protein A; D003520:Cyclophosphamide; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases