cytochrome-c-t and uranyl-acetate

Kidney is known as the most sensitive target organ for depleted uranium (DU) toxicity in comparison to other organs. Although the oxidative stress and mitochondrial damage induced by DU has been well investigated, the precise mechanism of DU-induced nephrotoxicity has not been thoroughly recognized yet.. Kidney mitochondria were obtained using differential centrifugation from Wistar rats and mitochondrial toxicity endpoints were then determined in both in vivo and in vitro uranyl acetate (UA) exposure cases.. Single injection of UA (0, 0.5, 1 and 2mg/kg, i.p.) caused a significant increase in blood urea nitrogen and creatinine levels. Isolated mitochondria from the UA-treated rat kidney showed a marked elevation in oxidative stress accompanied by mitochondrial membrane potential (MMP) collapse as compared to control group. Incubation of isolated kidney mitochondria with UA (50, 100 and 200μM) manifested that UA can disrupt the electron transfer chain at complex II and III that leads to induction of reactive oxygen species (ROS) formation, lipid peroxidation, and glutathione oxidation. Disturbances in oxidative phosphorylation were also demonstrated through decreased ATP concentration and ATP/ADP ratio in UA-treated mitochondria. In addition, UA induced a significant damage in mitochondrial outer membrane. Moreover, MMP collapse, mitochondrial swelling and cytochrome c release were observed following the UA treatment in isolated mitochondria.. Both our in vivo and in vitro results showed that UA-induced nephrotoxicity is linked to the impairment of electron transfer chain especially at complex II and III which leads to subsequent oxidative stress.

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Animals; Cell Proliferation; Cells, Cultured; Cytochromes c; Electron Transport Complex II; Electron Transport Complex IV; Glutathione; Hydrogen Peroxide; Kidney; Lipid Peroxidation; Male; Membrane Potential, Mitochondrial; Mitochondria; Organometallic Compounds; Oxidative Phosphorylation; Oxidative Stress; Rats; Rats, Wistar; Reactive Oxygen Species; Uranium

The effect of extremely low frequency and low amplitude magnetic fields on gap junctional permeability was investigated by using reconstituted connexin32 hemi channel in liposomes. Cytochrome c was loaded inside these proteoliposomes and its reduction upon addition of ascorbate in the bulk aqueous phase was adopted as the index of hemi channel permeability. The permeability rate of the hemi channels, expressed as DeltaA/min, was dependent on the incubation temperature of proteoliposomes. The effect of exposures to magnetic fields at different frequencies (7, 13 and 18 Hz) and amplitudes (50, 50 and 70 microT, respectively), and at different temperatures (16, 18 and 24 degrees C) was studied. Only the exposure of proteoliposomes to 18-Hz (B(acpeak) and B(dc)=70 microT) magnetic field for 60 min at 16+/-0.4 degrees C resulted in a significant enhancement of the hemi channel permeability from DeltaA/min=0.0007+/-0.0002 to DeltaA/min=0.0010+/-0.0001 (P=0.030). This enhancement was not found for magnetic field exposures of liposomes kept at the higher temperatures tested. Temperature appears to influence lipid bilayer arrangement in such a way as being capable to mask possible effects induced by the magnetic field. Although the observed effect was very low, it seems to confirm the applicability of our model previously proposed for the interaction of low frequency electromagnetic fields with lipid membrane.

Topics: Animals; Cell Membrane Permeability; Connexins; Cytochromes c; Gap Junction beta-1 Protein; Gap Junctions; Liposomes; Magnetics; Microscopy, Electron, Transmission; Organometallic Compounds; Rats; Temperature