These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Microsomal cytochrome P450 1A1 dependent monooxygenase activity in guinea pig heart: induction, inhibition, and increased activity by addition of exogenous NADPH-cytochrome P450 reductase.
    Author: McCallum GP, Horton JE, Falkner KC, Bend JR.
    Journal: Can J Physiol Pharmacol; 1993 Feb; 71(2):151-6. PubMed ID: 8319138.
    Abstract:
    Characterization of cytochrome P450 1A1 dependent monooxygenases in guinea pig heart revealed low rates of 7-ethoxyresorufin O-deethylation, which are markedly increased (20-fold) by treatment with beta-naphthoflavone, a polycyclic aromatic hydrocarbon. Both 7-ethoxyresorufin O-deethylation and 7-methoxyresorufin O-demethylation were found to be approximately 4-fold higher in microsomes prepared from the ventricle than the atrium of beta-naphthoflavone-induced guinea pigs. The low rates of 7-ethoxyresorufin O-deethylation in cardiac microsomes were due, at least in part, to a deficiency of the flavoprotein NADPH--cytochrome P450 reductase; addition of exogenous NADPH--cytochrome P450 reductase; addition of exogenous NADPH--cytochrome P450 reductase dramatically increased 7-ethoxyresorufin O-deethylation in cardiac microsomes of guinea pigs, before and after treatment with beta-naphthoflavone. N-Benzyl-1-aminobenzotriazole, a suicide substrate of cytochrome P450 1A1 in guinea pig, was able to inhibit almost all of the 7-ethoxyresorufin O-deethylase and 7-methoxyresorufin O-demethylase activities in polycyclic aromatic hydrocarbon induced guinea pig heart (88 and 71%, respectively), suggesting that cytochrome P450 1A1 coupled to NADPH--cytochrome P450 reductase in these microsomes inactivates itself by a suicidal mechanism. Addition of alpha-naphthoflavone, an inhibitor of cytochrome P450 1A isozymes, to cardiac microsomes from beta-naphthoflavone-induced guinea pigs resulted in greater than 95% inhibition of 7-ethoxyresorufin O-deethylase activity. The biological significance of these low levels of cytochrome P450 1A1 monooxygenase activity in guinea pig heart and their induction by polycyclic aromatic hydrocarbons are not currently understood.
    [Abstract] [Full Text] [Related] [New Search]