Hydrogen peroxide (H2O2) has been implicated in many stress conditions. Control of H2O2 levels is complex and dissection of mechanisms generating and relieving H2O2 stress is difficult, particularly in intact plants. We have used transgenic tobacco with approximately 10% wild-type catalase activity to study the role of catalase and effects of H2O2 stress in plants. Catalase-deficient plants sho...

Oxidative stress through the production of oxygen metabolites such as hydrogen peroxide (H2O2) increases vascular endothelial permeability. H2O2 stimulates ADP-ribose formation, which in turn opens transient receptor potential melastatin (TRPM)2 channels. Here, in endothelial cells, we demonstrate transcript and protein expression of TRPM2, a Ca -permeable, nonselective cation channel. We furth...

Recent in vivo studies establish that osteopontin (OPN) expression is hydrogen peroxide (H2O2)-dependent. However, the mechanisms by which H2O2 increases OPN expression remain poorly defined. OPN protein expression increased in an unusual biphasic pattern in response to H2O2. To investigate whether these increases were mediated through transcriptional and/or translational regulation of OPN, smo...

Cells have a wide range of capacities to remove extracellular hydrogen peroxide. At higher concentrations of extracellular H2O2 (micromolar) the rate of removal can be approximated by a rate equation that is first-order in the concentration of H2O2 and cell density. Here we present a method to determine the observed rate constant for the removal of extracellular H2O2 on a per cell basis. In the...

Mycoplasma iowae is a well-established avian pathogen that can infect and damage many sites throughout the body. One potential mediator of cellular damage by mycoplasmas is the production of H2O2 via a glycerol catabolic pathway whose genes are widespread amongst many mycoplasma species. Previous sequencing of M. iowae serovar I strain 695 revealed the presence of not only genes for H2O2 produc...

-Ketoglutarate dehydrogenase ( -KGDH), a key enzyme in the Krebs’ cycle, is a crucial early target of oxidative stress (Tretter and Adam-Vizi, 2000). The present study demonstrates that -KGDH is able to generate H2O2 and, thus, could also be a source of reactive oxygen species (ROS) in mitochondria. Isolated -KGDH with coenzyme A (HS-CoA) and thiamine pyrophosphate started to produce H2O2 after...

Dahl salt-sensitive (SS) and consomic, salt-resistant SS-13(BN) rats possess substantial differences in blood pressure salt-sensitivity even with highly similar genetic backgrounds. The present study examined whether increased oxidative stress, particularly H2O2, in the renal medulla of SS rats contributes to these differences. Blood pressure was measured using femoral arterial catheters in thr...

Endogenous reactive oxygen species (ROS) can act as modulators of neuronal activity, including synaptic transmission. Inherent in this process, however, is the potential for oxidative damage if the balance between ROS production and regulation becomes disrupted. Here we report that inhibition of synaptic transmission in rat hippocampal slices by H2O2 can be followed by electrical hyperexcitabil...

Mechanisms by which the lens protects against H2O2 are believed to include the metabolism of glutathione (GSH). In the present study, rabbit lenses were exposed to constant concentrations of H2O2 (0.01 to 0.1 mM) that were maintained in culture media with the use of a peristaltic pump. The rate at which H2O2 entered the lens was proportional to its concentration in the medium and reached 2.6 mu...

Dopamine-glutamate interactions in the striatum are critical for normal basal ganglia-mediated control of movement. Although regulation of glutamatergic transmission by dopamine is increasingly well understood, regulation of dopaminergic transmission by glutamate remains uncertain given the apparent absence of ionotropic glutamate receptors on dopaminergic axons in dorsal striatum. Indirect evi...