PURPOSE: To investigate the effects of dipyridamole (DPD) on the production of reactive oxygen species (ROS) and oxidative stress in cultured human trabecular meshwork cells (HTMC). METHODS: Antioxidant activity of DPD was determined by DPPH assay. Primarily cultured HTMC were exposed to 0, 20, and 50 microm DPD using serum-deprived media. The effect of DPD on the production of ROS was assessed with the DCHFDA assay. The effect of DPD on the t-butyl hydroperoxide (tBHP)-induced oxidative stress was assessed with resazurin assay. RESULTS: DPD showed significant antioxidant activity. DPD significantly decreased the production of ROS (p < 0.05) and improved cellular activity significantly after treatment with t-BHP (p < 0.05). DPD did not affect the generation of nitric oxides. CONCLUSIONS: DPD suppressed the formation of ROS and possessed cytoprotective activity against the oxidative stress in HTMC.
Dipyridamole ; Humans ; Oxazines ; Oxidative Stress ; Reactive Oxygen Species ; tert-Butylhydroperoxide ; Trabecular Meshwork ; Xanthenes

The present study was undertaken to examine the role of phospholipase A2 (PLA2) in oxidant-induced inhibition of phosphate transport in primary cultured rabbit renal proximal tubule cells. Uptakes of phosphate and glucose were dose-dependently inhibited by an oxidant t-butylhydroperoxide (tBHP), and the significant inhibition appeared at 0.025 mM of tBHP, whereas tBHP-induced alterations in lipid peroxidation and cell viability were seen at 0.5 mM. tBHP stimulated arachidonic acid (AA) release in a dose-dependent fashion. A PLA2 inhibitor mepacrine prevented tBHP-induced AA release, but it did not alter the inhibition of phosphate uptake and the decrease in cell viability induced by tBHP. tBHP-induced inhibition of phosphate transport was not affected by a PKC inhibitor, staurosporine. tBHP at 0.1 mM did not produce the inhibition of Na+-K+-ATPase activity in microsomal fraction, although it significantly inhibited at 1.0 mM. These results suggest that tBHP can inhibit phosphate uptake through a mechanism independent of PLA2 activation, irreversible cell injury, and lipid peroxidation in primary cultured rabbit renal proximal tubular cells.
Arachidonic Acid ; Cell Survival ; Glucose ; Lipid Peroxidation ; Phospholipases A2* ; Phospholipases* ; Quinacrine ; Staurosporine ; tert-Butylhydroperoxide

Using lipid bilayer reconstitution technique, we investigated the oxidation effect of t-butyl hydrogen peroxide (tBHP) on the single channel activity of the sarcoplasmic reticulum (SR) calcium release channels isolated from canine latissimus dorsi muscles. When 0.7% tBHP was added in the cytosolic side, the channel activity became suppressed (n = 7), and it was recovered by changing the solution to the control solution. The suppression was due to the change in the gating mode of the channel: before tBHP the channel opened to four sub-conductance levels, but it opened to only one level after tBHP. These effects by tBHP were different from the previous finding using hydrogen peroxide (H2O2), which may be explained by different oxidation patterns between the two oxidants.
Animal ; Calcium Channels/drug effects* ; Dogs ; Hydrogen Peroxide/pharmacology ; Peroxides/pharmacology* ; Sarcoplasmic Reticulum/metabolism ; Sarcoplasmic Reticulum/drug effects* ; tert-Butylhydroperoxide

BACKGROUND/OBJECTIVES: The objective of this study was to evaluate the protective effect of black rice extract (BRE) on tert-butyl hydroperoxide (TBHP)-induced oxidative injury in HepG2 cells. MATERIALS/METHODS: Methanolic extract from black rice was evaluated for the protective effect on TBHP-induced oxidative injury in HepG2 cells. Several biomarkers that modulate cell survival and death including reactive oxygen species (ROS), caspase-3 activity, and related cellular kinases were determined. RESULTS: TBHP induced cell death and apoptosis by a rapid increase in ROS generation and caspase-3 activity. Moreover, TBHP-induced oxidative stress resulted in a transient ERK1/2 activation and a sustained increase of JNK1/2 activation. While, BRE pretreatment protects the cells against oxidative stress by reducing cell death, caspase-3 activity, and ROS generation and also by preventing ERKs deactivation and the prolonged JNKs activation. Moreover, pretreatment of BRE increased the activation of ERKs and Akt which are pro-survival signal proteins. However, this effect was blunted in the presence of ERKs and Akt inhibitors. CONCLUSIONS: These results suggest that activation of ERKs and Akt pathway might be involved in the cytoprotective effect of BRE against oxidative stress. Our findings provide new insights into the cytoprotective effects and its possible mechanism of black rice against oxidative stress.
Apoptosis ; Biomarkers ; Caspase 3 ; Cell Death* ; Cell Survival ; Hep G2 Cells* ; Methanol ; Oxidative Stress ; Phosphotransferases ; Reactive Oxygen Species ; tert-Butylhydroperoxide

Antioxidant effects of serotonin and L-DOPA on neuronal tissues were examined by studying the oxidative damages of brain synaptosomal components. The study further explored the mechanism by which they exert protective actions. Serotonin and L-DOPA (1 muM to 1 mM) significantly inhibited lipid peroxidation of brain tissues by either Fe2+ and ascorbate or t-butyl hydroperoxide in a dose dependent fashion. Protective effect of serotonin on the peroxidative actions of both systems was greater than that of L-DOPA. Protein oxidation of synaptosomes caused by Fe2+ and ascorbate was attenuated by serotonin and L-DOPA. Protein oxidation more sensitively responded to L-DOPA rather than serotonin. Serotonin and L-DOPA (100 muM) decreased effectively the oxidation of synaptosomal sulfhydryl groups caused by Fe2+ and ascorbate. The production of hydroxyl radical caused by either Fe3+, EDTA, H2O2 and ascorbate or xanthine and xanthine oxidase was significantly decreased by serotonin and L-DOPA (1 mM). Equal concentrations of serotonin and L-DOPA restored synaptosomal Ca2+ uptake decreased by Fe2+ and ascorbate, which is responsible for SOD and catalase. Protective effects of serotonin and L-DOPA on brain synaptosomes may be attributed to their removing action on reactive oxidants, hydroxyl radicals and probably iron-oxygen complex, without chelating action on iron.
Antioxidants* ; Brain* ; Catalase ; Edetic Acid ; Hydroxyl Radical ; Iron ; Levodopa* ; Lipid Peroxidation ; Neurons ; Oxidants ; Serotonin* ; Synaptosomes* ; tert-Butylhydroperoxide ; Xanthine ; Xanthine Oxidase

BACKGROUND: Ischemic insult during operation could cause ischemic-reperfusion injuries in brain and memory impairments. Total intravenous anesthesia (TIVA) is preferred in brain surgery to promote the use of motor evoked potential monitoring and the use of opioids is common in TIVA. However there were few studies about ischemic protective effect of opioids to astrocytes. METHODS: We used astrocytes, which were derived from human brain. We divided groups by conditioning period; i) pre-culture, ii) post-culture, or iii) pre + post-culture. All groups were treated 100 nM hydromorphone. We measured reactive oxygen species (ROS) by flow cytometry with 2',7'-dichloroflurorescin diacetate. Then ROS in astrocytes which treated by opioid receptor antagonist were measured after treating 100 nM hydromorphone. RESULTS: ROS was reduced in hydromorphone treated group, as compared to the control group (only tert-butyl hydroperoxide [TBH] treated). There was no difference in pre-conditioned group and post-conditioned group. However, ROS was much more reduced in pre + post-conditioned group compared to pre-conditioned only or post-conditioned only group. Furthermore each selective micro-, delta- and kappa-opioid receptor antagonists partially negated the effect of hydromorphone. CONCLUSIONS: This study provides evidence that hydromorphone has both preconditioning and postconditioning effects on TBH-induced oxidative stress. Furthermore we proved each micro-, delta- and kappa-opioid receptor relates to protective mechanism of hydromorphone to astrocytes.
Analgesics, Opioid ; Anesthesia, Intravenous ; Astrocytes ; Brain ; Brain Ischemia* ; Evoked Potentials, Motor ; Flow Cytometry ; Humans ; Hydromorphone* ; Memory ; Oxidative Stress ; Reactive Oxygen Species ; Receptors, Opioid ; tert-Butylhydroperoxide

OBJECTIVETo establish the oxidative damage model of cochlea hair cells using organic oxidant t-BHP in vitro.

METHODSHEI-OC1 cells were exposed to t-BHP at 8 doses (30~4000 µmol/L) for 12 h. Trypan blue test was used to detected the cellular viability and MTT assay was utilized to measured the cellular proliferation. The intracellular ROS levels were determined by 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA).

RESULTSThe survival rates of HEI-OC1 cells started decrease significantly at the dose of 100 µmol/L t-BHP, the peak of decreased survival rates appeared at the doses of 200~800 µmol/L. The results of MTT assay demonstrated that 30 µmol/L t-BHP could promote cellular proliferation ability, when t-BHP concentrations were higher than 200 µmol/L, the cellular proliferation ability was inhibited. The results of DCFH-DA assay showed that there was no fluorescence in control group, the strong fluorescence was observed in positive control group, the weak fluorescence was observed in 30~50 µmol/L t-BHP groups, the bright fluorescence was observed in 100 µmol/L t-BHP group, still the stronger fluorescence was observed in 200~1000 µmol/L groups, but the cellular number decreased with the doses because of the lower cellular viability.

CONCLUSIONThe exposure to 100 µmol/L t-BHP for 12 h could simulate the oxidative damage induced by noise in cochlear hair cells.

Cell Survival ; Cells, Cultured ; Hair Cells, Auditory ; drug effects ; pathology ; Humans ; Noise ; adverse effects ; Oxidation-Reduction ; Oxidative Stress ; Reactive Oxygen Species ; analysis ; tert-Butylhydroperoxide ; toxicity

This paper was to explore the effect of blood oxygen saturation (SO2) on oxidative damages of erythrocytes under the condition of oxidative stress. Keeping SO2 of cultured erythrocytes in vitro at the states of 0.3, 0.5, 0.7, 0.9 and 0.98, respectively, we induced oxidative stress by tert-buthylhydroperoxide (BHP, 0.15 mmol/L of final concentration). After incubation, antioxidant capacity was assessed by measuring content of reduced glutathin hormone (GSH) in erythrocytes. Methemoglobin (MetHb) content, lipid peroxidation (thiobarbituric acid-reactive substances, TBARS) and denatured globin-chains on the plasma membrane were measured to assess the extent of oxidative damages. The results showed that in the presence of BHP, GSH contents increased from 0.3 to 0.98 groups; MetHb, TBARS and globin-chains levels all dropped with the rise of SO2. In conclusion, antioxidant capacity and oxidative damages of erythrocytes are closely related to SO2, declined SO2 could promote oxidative damages of erythrocytes.
Cells, Cultured ; Erythrocytes ; cytology ; metabolism ; physiology ; Glutathione ; blood ; Humans ; Methemoglobin ; metabolism ; Oxidative Stress ; drug effects ; Oximetry ; methods ; Oxygen ; blood ; Thiobarbituric Acid Reactive Substances ; metabolism ; tert-Butylhydroperoxide ; toxicity

The effect of an organic peroxide, t-butylhydroperoxide (t-BHP), on glutamate uptake was studied in synaptosomes prepared from cerebral cortex. t-BHP inhibited the Na+/-dependent glutamate uptake with no change in the Na+/-independent uptake. This effect of t-BHP was not altered by addition of Ca2+ channel blockers (verapamil, diltiazem and nifedipine) or PLA2 inhibitors (dibucaine, butacaine and quinacrine). However, the effect was prevented by iron chelators (deferoxamine and phenanthroline) and phenolic antioxidants (N,N'-diphenyl-phenylenediamine, butylated hydroxyanisole, and butylated hydroxytoluene). At low concentrations (< 1.0 mM), t-BHP inhibited glutamate uptake without altering lipid peroxidation. Moreover, a large increase in lipid peroxidation by ascorbate/Fe2+ was not accompanied by an inhibition of glutamate uptake. The impairment of glutamate uptake by t-BHP was not intimately related to the change in Na+/-K+/-ATPase activity. These results suggest that inhibition of glutamate uptake by t-BHP is not totally mediated by peroxidation of membrane lipid, but is associated with direct interactions of glutamate transport proteins with t-BHP metabolites. The Ca2+ influx through Ca2+ channel or PLA2 activation may not be involved in the t-BHP inhibition of glutamate transport.
Antioxidants ; Brain* ; Butylated Hydroxyanisole ; Carrier Proteins ; Cerebral Cortex ; Chelating Agents ; Diltiazem ; Glutamic Acid* ; Iron ; Lipid Peroxidation ; Membranes ; Phenol ; Synaptosomes* ; tert-Butylhydroperoxide*

BACKGROUND: Normal erythrocyte is deformable and this facilitates blood flow in the capillaries. Oxidative stress reduces the deformability of erythrocytes, and influences on blood flow in microcirculation. The objective of this study was to investigate the deformability of erythrocytes exposed to oxidative stress, the protective effects of verapamil and ascorbic acid against oxidative damages in erythrocytes, and the value of the microfluidic ektacytometer, RheoScan-D (RheoMeditech, Korea) in clinical application. METHODS: Effects of oxidative stress on erythrocytes were investigated using tert-butyl hydroperoxide (tBHP). Before exposure to tBHP, the erythrocytes were pretreated with verapamil and ascorbic acid to examine their protective effect against oxidative damages. The deformability of erythrocytes was measured by the microfluidic ektacytometer, RheoScan-D. RESULTS: When treated with tBHP, the deformability of erythrocytes was decreased (P<0.01) and methemoglobin (metHb) formation and mean corpuscular volume (MCV) of erythrocytes were increased (P<0.01, P<0.05) compared to those of the untreated control cells. Compared to the tBHP treated cells, pretreatment with verapamil increased the deformability of erythrocytes (P<0.01) and decreased metHb formation (P<0.01) and MCV (P<0.05). Likewise, pretreatment with ascorbic acid increased the deformability of erythrocytes (P<0.01) and decreased metHb formation (P<0.01). CONCLUSIONS: Oxidative stress reduces the deformability of erythrocytes and the deformability could be one of markers for oxidative damage. Verapamil and ascorbic acid have protective role against tBHP induced oxidative stress. The ektacytometer, RheoScan-D used in this study is convenient for clinical measurement and could be used in various fields of clinical medicine.
Adult ; Antioxidants/pharmacology ; Ascorbic Acid/*pharmacology ; Calcium Channel Blockers/pharmacology ; Erythrocyte Deformability/*drug effects ; Erythrocytes/drug effects/physiology ; Humans ; Male ; Microfluidic Analytical Techniques/*instrumentation ; Oxidative Stress ; Statistics, Nonparametric ; Verapamil/*pharmacology ; tert-Butylhydroperoxide/*pharmacology