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: Effect of phenobarbital and 3-methylcholanthrene on biphenyl hydroxylations and fluidity of rat liver microsomal membranes.
    Author: Deliconstantinos G.
    Journal: In Vivo; 1988; 2(6):393-8. PubMed ID: 2979861.
    Abstract:
    The metabolism of biphenyl by rat liver microsomes after administration of phenobarbital and 3-methylcholanthrene was studied. Phenobarbital increased the activity of biphenyl-4-hydroxylase and 3- methylcholanthrene increased the activity of both biphenyl-4-hydroxylase and biphenyl-2-hydroxylase as compared to non-treated (control) rats. Phenobarbital increased the lipid fluidity while 3-methylcholanthrene increased the lipid rigidity of microsomal membranes labeled with 1,6-diphenyl-1,3,5-hexatriene (DPH), as indicated by the steady-state fluorescence anisotropy [(ro/r)-1]-1. Arrhenius plots of [ro/r)-1]-1 indicated that the lipid phase separation of the control membrane at 22.1 +/- 1.1 degrees was reduced in phenobarbital treated (14.5 +/- 0.8 degrees) and increased in 3-methylcholanthrene treated rats (32.7 +/- 2.2 degrees). Arrhenius plots of biphenyl-4-hydroxylase and biphenyl-2-hydroxylase activities exhibited a break point at 21.8 +/- 1.1 degrees and 32.1 +/- 2.1 degrees, respectively, suggesting differences in the interactions of the enzymes with their annular lipids. It is suggested that biphenyl-4-hydroxylase requires a liquid state of its lipid microenvironment to be fully active, while biphenyl-2-hydroxylase a gel state of its lipid microenvironment. These studies provide a basis for postulating that a "non-genomic" mechanism of phenobarbital and 3-methylcholanthrene induces cytochrome P-450 dependent monoxygenases.
    [Abstract] [Full Text] [Related] [New Search]