Article

Fluidity of the microsomal membrane and cytochrome P450 reduction kinetics of pig liver microsomes as a consequence of organic solvent impact.

Biophysical Department, University of Bremen, Germany.
Xenobiotica (Impact Factor: 1.98). 02/1993; 23(1):71-8. DOI: 10.3109/00498259309059363
Source: PubMed

ABSTRACT 1. The effect of the aromatic solvents toluene, xylene and ethylbenzene on microsomal membrane fluidity and anaerobic NADPH-reduction kinetics were studied. 2. The relation of membrane fluidity to the kinetics of cytochrome P450 reduction by NADPH-cytochrome P450 reductase was examined with regard to a membrane-mediated molecular organization of the multienzyme components of the monooxygenase system. 3. Membrane fluidity changes were detected with the steady-state pyrene excimer formation method and with fluorescence lifetime measurements after incubation of the microsomes with organic solvents. 4. Increase in membrane fluidity in presence of organic solvents leads to a small but significant decrease of the rate constant of the cytochrome P450 reduction kinetics and a change in the relative amplitudes of the components of the biphasic response. 5. The results support the idea of a molecular organization of cytochrome P450 in clusters. Fluidization of the microsomal membrane by organic solvents increase the cytochrome P450 cluster formation.

0 Bookmarks
 · 
27 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Rats (Rattus norvegicus) were intraperitoneally injected with a 100 mg kg(-1) dosage of benzene, a toxic and carcinogenic agent widely used for industrial purposes. Changes in lactate dehydrogenase (LDH), alkaline phosphatase (ALP), alanine amino transferase (ALT), aspartate amino transferase (AST) activities in serum of rats were investigated at 2, 4, 8, 16, 32, and 64 h following injection. Serum physiological was administered to control group. Activities were measured using autoanalyzer. Benzene caused significant activations in LDH, ALP, and AST activities in the serum at some test hours (p < 0.05). When compared with the control groups, although an increase occurred in ALT activity, it was seem that this increase wasn't significant (p > 0.05).
    Environmental Monitoring and Assessment 06/2008; 154(1-4):23-7. · 1.68 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Swiss Albino (Rat rattus norvegicus) rats were intraperitoneally injected with a 100 mg kg(-1) dosage of benzene, a toxic and carcinogenic agent widely used for industrial purposes. Changes in the adenosine deaminase (ADA) activity in the liver, kidney and serum of rats were investigated at 0, 2, 4, 8, 16, 32 and 64 h following injection. Serum physiological was administered to each control group. Enzyme activities were measured spectrophotometrically. Our purpose was to further investigations of some diseases caused by benzene, and present evidence of variations in the activity of ADA enzyme effected by benzene. While benzene caused significant inhibitions in ADA activity in the liver at 16 and 32 h and at 0.05 probability level, no significant inhibition or activation occurred at other test periods (hours). ADA activity did not present any significant variation in the kidneys. It was observed that ADA activity displayed similar patterns in the control groups. Comparisons of ADA activities in the two groups showed a statistically significant decrease between 4(th) and 64(th) hours (p< 0.05), demonstrating a direct correlation between benzene and its effects on ADA enzymes.
    Journal of biochemistry and molecular biology 05/2007; 40(3):295-301. · 2.02 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The effects of a 100 mg.kg -1 dose of benzene, an occupational and environmental toxicant, were investigated on serum, estradiol and testosterone concentrations as well as lactate dehydrogenase (LDH), alkaline phosphatase (ALP), alanine amino transferase (ALT), aspartate amino transferase (AST), and pyruvate kinase (PK) activities in the liver and kidney of rats after 2, 4, 8, 16, 32, 64 and 72 hours. Benzene was given intraperitoneally to Rat rattus norvegicus and the control groups were injected with physiological saline. Liver tissue LDH, AST, ALT and kidney tissue LDH, ALP, AST, ALT activities were lower in the benzene treated group when compared to those in the control group (p<0.05). A tendency for an increase in the liver tissue ALP activity was observed, which was significant at 8 and 16 hours (p<0.05). There were significant increases in ALT in the liver and LDH, AST, and ALT enzyme activities in the kidney tissue at the beginning of the experiment in both groups and these activities were found to be nearly the same. Pyruvate kinase enzyme activities in rats given benzene were slightly increased in kidney tissues but lower in liver tissues. Differences between the groups tended to disappear towards the end of the experimental period. However, serum estradiol concentrations in the serum diverged significantly (p<0.05). Consequently, it was found that benzene administration led to some changes (increases then decreases) in LDH, ALP, ALT, AST, and PK activity and estradiol, testosterone concentrations in different tissues of rats. Possible causes of the increases and decreases in enzyme activities and hormone levels are discussed.
    Acta Veterinaria. 01/2003;