Degree Of Cell Damage Research Articles

Study on the cytotoxicity of functionalized muitl-wailed carbon nanotubes against vascular endothelial cells

Objective The broad range of increasing applications for carbon nanotubes (CNTs) may bring hazardous exposure to humans and other biological systems. Modification of CNTs with different chemical groups was used to enhance solubility and was likely to result in different toxicity. The current study was designed to study the cytotoxicity of pristine CNTs (p-CNTs) and functionalized CNTs (f-CNTs) against vascular endothelial cells,which mediate many key biological processes in the body. Methods Vascular endothelial cells (VECs) were isolated from human umbilical veins and identified by immunochemical staining. MTT assay was employed to test the viability of the VECs exposed to different concentrations of p-CNTs or f-CNTs for up to 72 h. The mor-phology of the cells was observed under transmission electron microscope. Results It was demonstrated that both p-CNTs and f-CNTs induced decreased cell viability in a dose dependent manner, whereas neither of the medium dialyzed against p-CNTs or f-CNTs showed any cytotoxicity against the VECs. The eytotoxicity of p-CNTs was greater than that of f-CNTs after at 24 h of exposure. However, at 48 h and 72 h of exposure, f-CNTs resulted in greater decrease of cell viability as compared to p-CNTs. Transmission electron microscopic observation showed that there were much more CNT aggregates in the cytoplasm of f-CNTs treated cells than those of p-CNTs treated cells. It was also observed that the p-CNT aggregates are much more condensed than f-CNTs aggregates. Conclusion It is likely that the aggregation may play greater role in the cytotoxicity of p-CNTs, whereas the sur-face chemistry was the major factor responsible for that of f-CNTs. Increased number of f-CNTs enveloped by the cells may cause greater degree of cell damage or interfere the mass transportation in the cytoplasm, and hence in-duced increased loss of cell viability. Key words: Cytotoxicity; Vascular endothelial cells; Aggregates; Surface chemistry

Infection of bovine oviduct cell cultures with Chlamydophila abortus

Bovine infertility is a major cause of loss in the livestock industry. In the present study bovine oviduct cell cultures were infected with a Chlamydophila abortus strain. A direct evaluation of infection was performed by means of May Grünwald-Giemsa and immunocytochemistry for chlamydial LPS, which revealed inclusion bodies and vacuolisation. SEM and TEM analysis of infected cells showed various degrees of cell damage and conglutination of microvilli. This finding suggests that cattle infertility may result from an alteration of oviduct environment caused by multiplication of C. abortus. This microorganism, among other infectious agents, could be considered a potential causative agent of bovine infertility.

Comparison of dyes for cataract surgery. Part 1: cytotoxicity to corneal endothelial cells in a rabbit model

The authors experimentally evaluated the corneal endothelial cytotoxicity of dyes used for capsule staining in cataract surgery. Cultured endothelial cells of New Zealand rabbits were exposed for 1 minute to various concentrations of one of the following dyes: indocyanine green (ICG), methylene blue (MB), gentian violet (GV), trypan blue (TB), and fluoresce in sodium (FS). The effect of longer exposure (up to 10 minutes) to ICG 0.25% was also investigated. The degree of cell damage was determined by in vitro staining with TB and comparison with results in a control group. Indocyanine green 0.25%, MB 0.20%, GV 0.01%, TB 0.40%, and FS 10% did not induce considerable damage to endothelial cells. Significant cytotoxicity was observed with the following or higher dye concentrations: ICG 0.50%, MB 0.50%, and GV 0.10%. Exposure to ICG 0.25% for 1 to 10 minutes showed a trend toward cytotoxicity after 10 minutes. On transmission electron microscopy, corneal endothelial cells that had been exposed to 0.50% ICG showed remarkable organelle swelling and disruption, electron-dense granules, and cell lysis. The authors conclude that 1 minute of exposure to ICG 0.25%, MB 0.20%, GV 0.01%, TB 0.40%, and FS 10% appears to be safe as determined by no cytotoxic effects on rabbit corneal endothelial cells in culture.—Michael D. Wagoner

Comparison of dyes for cataract surgery

To investigate the corneal endothelial cytotoxicity of dyes for capsule staining in cataract surgery. Department of Ophthalmology and Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan. Cultured corneal endothelial cells of New Zealand white rabbits were exposed for 1 minute to 1 of the following dyes (various concentrations): indocyanine green (ICG), methylene blue (MB), gentian violet (GV), trypan blue (TB), and fluorescein sodium (FS). The degree of cell damage was determined by in vitro staining with TB and comparison with results in a control group. The effect of longer exposure (up to 10 minutes) to ICG 0.25% was also investigated. Structural changes in corneal endothelial cells after dye exposure were evaluated by light microscopy and transmission electron microscopy (TEM). Indocyanine green 0.25%, MB 0.20%, GV 0.01%, TB 0.40%, and FS 10% did not induce significant damage to corneal endothelial cells. Significant cytotoxicity was observed with the following or higher dye concentrations: ICG 0.50%, MB 0.50%, and GV 0.10%. Exposure to ICG 0.25% for 1 to 10 minutes showed a trend toward cytotoxicity after 10 minutes. On TEM, corneal endothelial cells that had been exposed to ICG 0.50% showed remarkable organelle swelling and disruption, electron-dense granules, and cell lysis. One minute of exposure to ICG 0.25%, MB 0.20%, GV 0.01%, TB 0.40%, and FS 10% appeared to be safe as determined by no cytotoxic effects on rabbit corneal endothelial cells in culture.

Transient decrease in blood heterophils and sustained liver damage caused by calicivirus infection of young rabbits that are naturally resistant to rabbit haemorrhagic disease

Young rabbits are naturally resistant to rabbit haemorrhagic disease (RHD) caused by the same calicivirus that kills, within 3 days, nearly all adult animals. We have investigated changes in blood leukocytes, and in the morphology and biochemistry of the liver (the organ where caliciviruses replicate) of young rabbits undergoing benign infection by the RHD virus. Four-week-old rabbits were infected with a calicivirus inoculum having a titre of 2 12 haemagglutination units either sacrificed 18, 24, 48 and 72 h later, or kept for follow-up studies up to 21 days after inoculation. The infection caused an acute and transient decrease in blood heterophils, and sustained enhancement in hepatic transaminases. Inflammatory infiltrates of the liver were seen in all animals after 24 h of infection; they had a predominant midlobular location. Hepatocytes could present different degrees of cell damage, including cell death; these lesions were limited to the liver cells located around the inflammatory infiltrates. Liver transaminases peaked 24–48 h after calicivirus infection; this was the same timing when liver infiltration and hepatocyte damage were more evident. No alterations of other parameters of liver biochemistry were observed. We conclude that calicivirus infection of young rabbits causes a subclinical disorder characterised by an acute and transient decrease in circulating heterophils, and focal liver damage that is expressed by intralobular infiltration by heterophils, initially, and, later on, by mononuclear cells. Our finding of persistence of increased values of liver transaminases suggests chronicity of the infection in young rabbits. We propose that, although resistant to RHD, young rabbits infected by calicivirus may be long-term carriers of the infectious agent and, thus, become a major source of transmission of the virus.

Effects of cell damage and glycosaminoglycan degradation on available extravascular space of different dextrans in a rat fibrosarcoma

Drug delivery to solid tumors may be enhanced through increasing the available volume fraction ( K AV ) of drugs. Therefore, two approaches were investigated that may increase K AV of dextrans in a rat fibrosarcoma: (a) damaging cells in tumours via ex vivo incubation of tumour tissues, and (b) degrading tumour glycosaminoglycans (GAGs) with exogenous hyaluronidase. The molecular weights of dextrans used in this study were ~ 10 000 (D10), 70 000 (D70) and 2 000 000 (D2000), respectively. It was found that GAG degradation had minimal effects on K AV of dextrans. Ex vivo incubation at 37°C for up to 3 h caused only minor cell damage and had minimal effects on K AV of D10 and D70. However, the ex vivo incubation reduced K AV of D2000 ( p < 0.05). When the incubation at 37°C was maintained for 20 h, the amount of viable cells in tumours was reduced by 56% and K AV of all dextrans were significantly increased ( p < 0.05). Ex vivo incubation at 41°C for 3 h caused similar cell damage to that at 37°C for 20 h, but only K AV of D10 and D70 were increased significantly ( p < 0.05). There was no significant change in K AV of D2000, although it was higher than that in tumours incubated at 37°C for 3 h ( p < 0.05). These data suggest that cell damage is a more effective approach than GAG degradation for increasing K AV of macromolecules and that the amount of increase depends on the degree of cell damage and the size of molecules.

Bread wheat gliadin cytotoxicity: a new three‐dimensional cell model

Background: In an attempt to clarify the role of gliadin toxicity in the pathogenesis of gluten intolerance (celiac disease), previous in vitro studies have been based on two‐dimensional human cell cultures. However, the specific morphological and biochemical properties of in vivo tissue are better maintained in three‐dimensional cell cultures (multicellular spheroids, MCS). The aim of this study was to develop a three‐dimensional in vitro model to investigate the effects of gliadin on epithelial cells and broaden our understanding of the early tissue damage occurring in celiac disease. Methods: The three‐dimensionally growing Lovo cell line was exposed to increasing concentrations of peptic‐tryptic‐digested bread wheat gliadin (from 125 to 1000 μg/mL) for 7 days in order to evaluate cell viability (colony‐forming assay), and at the standard concentration of 500 μg/mL for 7 days in order to evaluate MCS diameters, volumes and cell morphology using light and electron microscopy. Results: In comparison with the controls, the cell viability of the gliadin‐treated MCS was significantly reduced (20–80%), but there was no difference in size. Various degrees of cell damage (autophagic vacuoles and intra‐cytoplasmic lipid‐like droplets) were detected by both light and electron microscopy. Conclusion: This is the first study investigating the effects of gliadin on MCS. Lovo MCS seem to be responsive to gliadin exposure, thus confirming previous results obtained using two‐dimensional cell cultures. The data suggest that three‐dimensional cell cultures may be useful in broadening our understanding of some of the early effects of gliadin peptides on epithelial cells.

Bread wheat gliadin cytotoxicity: a new three-dimensional cell model

Background: In an attempt to clarify the role of gliadin toxicity in the pathogenesis of gluten intolerance (celiac disease), previous in vitro studies have been based on two‐dimensional human cell cultures. However, the specific morphological and biochemical properties of in vivo tissue are better maintained in three‐dimensional cell cultures (multicellular spheroids, MCS). The aim of this study was to develop a three‐dimensional in vitro model to investigate the effects of gliadin on epithelial cells and broaden our understanding of the early tissue damage occurring in celiac disease. Methods: The three‐dimensionally growing Lovo cell line was exposed to increasing concentrations of peptic‐tryptic‐digested bread wheat gliadin (from 125 to 1000 μg/mL) for 7 days in order to evaluate cell viability (colony‐forming assay), and at the standard concentration of 500 μg/mL for 7 days in order to evaluate MCS diameters, volumes and cell morphology using light and electron microscopy. Results: In comparison with the controls, the cell viability of the gliadin‐treated MCS was significantly reduced (20–80%), but there was no difference in size. Various degrees of cell damage (autophagic vacuoles and intra‐cytoplasmic lipid‐like droplets) were detected by both light and electron microscopy. Conclusion: This is the first study investigating the effects of gliadin on MCS. Lovo MCS seem to be responsive to gliadin exposure, thus confirming previous results obtained using two‐dimensional cell cultures. The data suggest that three‐dimensional cell cultures may be useful in broadening our understanding of some of the early effects of gliadin peptides on epithelial cells.

Neuroprotective activity of CHF3381, a putative N-methyl-D-aspartate receptor antagonist.

The aim of this study was to evaluate the neuroprotective effect of CHF3381, a novel putative NMDA antagonist characterized by a good therapeutic index. We have compared the effects of CHF3381 on kainate seizure-induced neurodegeneration with those produced by the non competitive NMDA receptor antagonist MK-801 and by the Na channel blocker lamotrigine. All compounds have been employed at doses incapable of preventing or attenuating seizures. The fluorescent marker Fluoro-Jade B has been used to identify degenerating cells. Animals pretreated with lamotrigine presented the same degree of cell damage as the controls. As for the controls, a clear correlation was also observed between seizure severity and neurodegeneration. In contrast, MK-801 and CHF3381 completely prevented cell damage. These data indicate that CHF3381 may be successfully utilized in neurological disorders characterized by or associated with neurodegenerative excitotoxicity.

Corneal endothelial cytotoxicity of diluted povidone–iodine

Purpose To assess corneal endothelial toxicity of diluted povidone–iodine (PI) in vivo and in vitro. Setting Cell Biology Laboratory and the Laboratory for Intraocular Microsurgery and Implants, Goldschleger Eye Research Institute, Sackler School of Medicine, Tel-Aviv University, Chaim Sheba Medical Center, Tel-Hashomer, Israel. Methods In an in vitro study, cultured bovine corneal endothelial cells were exposed to diluted PI. The degree of cell damage was determined by staining with trypan blue and by comparing the results to those in a control group. In an in vivo study, a single dose of diluted PI was injected into the anterior chamber of rabbit eyes, completely replacing the aqueous humor. The eyes were evaluated by clinical examination, specular microscopy, pachymetry, pneumotonometry, and histopathology and compared to a control group injected with a balanced salt solution. Results In vitro, PI concentrations of 0.05% or less did not induce endothelial cell damage. Significant damage was observed with a PI concentration of 0.1%. Calf serum concentrations of 1% and higher in the culture media protected the endothelial cell monolayer from cytotoxic damage by PI. Aqueous humor did not have a similar effect. In vivo, PI concentrations of 0.1% or less did not induce changes in corneal endothelium morphology or function as assessed by specular microscopy and pachymetry. A PI concentration of 1% served as a positive control, causing corneal edema and endothelial cell loss as demonstrated by pachymetry, histopathology, and elevated intraocular pressure. Conclusions The concentrations of PI tolerated by animal endothelium in vitro and in vivo were higher than the reported bactericidal levels. These findings justify further investigation of the safety and efficacy of PI for intracameral prophylaxis during surgery.

Comparative study of two spruce species in a polluted mountainous region

Summary Tolerance to pollution and climatic conditions are compared in Colorado blue spruce ( Picea pungens ) and Norway spruce ( Picea abies ) from two adjacent stands in the Krušné Hory Mountains, Czech Republic. The anatomy of needles was described quantitatively using image analysis, and the content of photosynthetic pigments, accumulation of lignin and phenolics, and reflective properties of needles of the two species were compared. Anatomical and morphological adaptations of Colorado blue spruce needles (i.e. lower needle surface area: volume ratio) suggested greater potential resistance to air pollution than Norway spruce. However, no difference in the degree of cell damage was recorded. Although concentrations of chlorophyll, carotenoids and their ratios were similar, lignification and phenolic accumulation was greater in Norway spruce. The red edge inflection point, as well as stress indices and reflectance ratios, suggested an age‐dependent increase in needle damage of both species. Needles of young Colorado blue spruce and Norway spruce exhibit the same degree of damage in response to air pollutants.

Gliotoxic action of glutamate on cultured astrocytes.

Because of the well-documented importance of glutamate clearance by astrocytes in protecting neurons against excitotoxicity, it was interesting to examine whether L-glutamate exerts a toxic action on cultured astrocytes. Cell damage was evaluated by measuring activity of lactate dehydrogenase (LDH) released into the culture medium. Exposure of astrocyte cultures of the neonatal rat cerebral cortex to L-glutamate resulted in a concentration- and time-dependent increase in the release of LDH. L-Glutamate-induced gliotoxicity appeared to be mediated predominantly by the increase of oxidative stress because the reduced glutathione content and its effects were almost completely blocked by vitamin E and pyrrolidinedithiocarbamate. To support this notion further, the supplementation or depletion of intracellular reduced glutathione content attenuated or worsened L-glutamate toxicity, respectively. Activation of the glutamate transporter mimicked the action of L-glutamate on astrocytes. In addition, degrees of cell damage were not directly correlated to the levels of glutamate uptake. Moreover, the mechanism of this toxicity required energy and macromolecular synthesis. Taken together, brief exposure to L-glutamate resulted in glutamate uptake and cell swelling, whereas sustained exposure injured astrocytes via oxidative stress instead of the excitatory mechanism.

In Vitro Cytotoxicity of Various Forms of Cobalt for Rat Alveolar Macrophages and Type II Pneumocytes

It has been shown that cobalt (Co) and the mixture cobalt–tungsten carbide (CoWC) are cytotoxic for alveolar macrophages (AM) and alveolar type II cells (AT-II), but the exact mechanisms of toxicity are not entirely elucidated. In this study, we exposed primary cultures of AT-II and AM, in vitro, to different forms of Co (Co particles, CoWC particles, CoCl2) and assessed cell damage using the dimethylthiazol diphenyl tetrazolium bromide test. In some experiments, inserts were used to separate the particles from the cells. The results show that AT-II are twice as sensitive to the effects of 100 μg Co particles/well (1.88 cm2) than AM. For this latter cell type, the presence of WC almost doubled (at 25 μg Co/well) the toxic effects compared to pure Co, but this synergy between Co and WC only occurred if the particles were in close contact with the cells. Lactalbumin and, to a lesser degree, EDTA were able to reduce the toxicity of Co, CoWC, and CoCl2 for AT-II and AM. CoCl2 showed a similar toxicity for AT-II and AM. The use of Co-conditioned medium revealed that Co particles are “aged” after having been incubated for 24 h in an aqueous medium and are then no longer able to cause the same degree of cell damage as fresh Co particles (71 versus 15% viability for 100 μg Co/well). The time course of the toxicity of the different forms of Co for AT-II and AM showed different patterns in causing cell damage, suggesting different action mechanisms. Evaluation of cell damage by electron microscopy was consistent with biochemical indices. Overall, our results indicate that the Co ion does play a role in the toxicity of both Co particles and CoWC particles.

Apoptotic degeneration induction in retinal cells by acute ocular hypertension and neuroprotection by troxolol

SummaryThe effects of acute experimental ocular hypertension on retinal cells have been studied. IOP levels and degree of cell damage have been evaluated by cytochemical and DNA analysis, by which the degeneration, necrotic and apoptotic modalities were observed. Possible pharmacological approaches, e.g. neuroprotection with troxol, have been determined for the prevention of the degenerative events that may be ascribed, at least in part, to oxidizing processes.

Prognostic value of serum neuron-specific enolase levels after head injury

Neuron-specific enolase (NSf) is a dimeric cytoplasmic enzyme detected in high levels in neurons and acts in the glycolytic pathway. It is known that there is a quantitative relationship between the concentration of serum NSf and the degree of cell damage in the central nervous system. We examined serum levels of NSf by enzyme immunoassay in 89 patients with head injury and aimed to evaluate its relationship with neurological status and prognosis of the patients. [Neural Res 1998; 20: 418–420]

Cartilage shaping using the Holmium: YAG laser without tissue ablation

Reshaping cartilage is a clinical problem and we are using a novel technique to solve this. Objective: To determine the mechanical, thermal, and optical changes in human cartilage in vitro during the phenomenon of ‘stress relaxation using the Holmium: YAG laser’. To define the parameters of energy intensity, pulse duration and repetition rate which produce ‘stress relaxation’ whilst minimizing chondrocyte damage. Method: Thirty-three pieces of human nasal septal cartilage were studied in vitro. Parameters including laser wavelength, pulse duration and repetition rate were measured. Tissue temperature was detected with a needle-shaped thermocouple of 30-μm diameter. The thermodynamic characteristics of the ‘bound-to-free’ phase transformation of water in cartilage were studied by FTIR spectroscopy. The structure of cartilage was examined by light and scanning electron microscopy and changes in chondrocytes were assessed using a semiquantitative method according to the degree of cell damage and the proportion of cells affected. Results: The mechanism of laser-induced stress relaxation of cartilage was found to be due to transformation and movement of the bound water in the cartilage (about 5% of the total water). There was no evidence of matrix damage although there were some microscopic changes of focal vacuolation and nuclear condensation of chondrocytes at energy levels required to produce stress relaxation. The optimum parameters were found to be a wavelength of 2.1 μm, a pulse energy of 0.5 J, a duration of 0.5 ms, a repetition rate of 5 Hz, and a spot diameter from 4.0 to 7.8 mm. An irradiation time of 4 s was needed to produce cartilage shaping. Conclusion: The conditions which produce stress relaxation using the Holmium: YAG laser show promise as a method of reshaping cartilage.

Neuron-specific enolase concentrations in serum and cerebrospinal fluid in patients with no previous history of neurological disorder

Studies of cerebrospinal fluid (CSF) concentrations of neuron-specific enolase (NSE) in patients with neurological lesions indicate a quantitative relation between the degree of cell damage in the central nervous system (CNS) and the concentration of this CNS-specific protein. We collected serum and CSF from 63 males and 24 females undergoing various surgical procedures in spinal anaesthesia. The patients had no actual or previous history of neurological disease. The mean value of NSE in serum was 7.1 +/- 3.6 micrograms/L. NSE concentrations in CSF demonstrated age- and sex-dependency, with an increase with age from 21 to 84 years and significantly higher levels in males than in females. Therefore, age- and sex-matched reference values have to be used when NSE is evaluated in CSF in patients with different neurological disorders.

Spontaneous Occurrence of Early Region 1A Reiteration Mutants of Type 5 Adenovirus in Persistently Infected Human T-Lymphocytes

Mutants of type 5 adenovirus (Ad5) with reiterated DNA sequences in the E1a region appeared in a human T-lymphocyte cell line, Molt-4, persistently infected with H5sub304, a deletion/substitution mutant that has a wild-type phenotype in viral replication. Endonuclease analyses and DNA sequencing revealed DNA reiteration in each mutant. In the four representative mutants investigated, the DNA reiterations all started within a six-base-pair consensus sequence, G(or C)CTGTG, located in the second exon of the E1a region (at nt 1333, 1367, or 1419). There was not any DNA homology between the breakpoints in the second exon and the inserting sequences (starting at nt 532, 710, or 792). Northern analyses suggested that the reiterated splicing sites of the representative mutants were all used in RNA splicing, and the closest donor and recipient joints were used most frequently. These observations imply that during persistent infection Ad5 underwent spontaneous mutations by sequence-specific breakage and nonhomologous end–end joining recombination events. These E1a reiteration mutants could be propagated in HeLa, A549, and KB cells; they were genetically stable; and they killed CREF cells at a strikingly high frequency. Preliminary observations tend to correlate this CREF cell killing with the accumulation of the early viral proteins and/or viral DNA in the infected cells. This degree of cell damage was not observed in Ad5wt or H5sub304 infection of CREF cells. The observed E1a reiterations provide a model to gain insight into understanding the evolutionary events of some, if not all, adenovirus types during many years of symbiotic, persistent relationship in human tonsils and adenoids and possibly other lymphoid organs.

Phosphatidylethanolamine and sarcolemmal damage during ischemia or metabolic inhibition of heart myocytes.

Phosphatidylethanolamine (PE) is a nonbilayer-preferring and fusogenic phospholipid. It is kept in the bilayer configuration by interaction with other phospholipids in biologic membranes. However, reorganization of the membrane phospholipids could lead to expression of the nonbilayer nature of PE and induce bilayer instability. During ischemia a transbilayer reorganization of sarcolemmal PE is observed, and results have been published that suggest a lateral phase separation in the inner sarcolemmal leaflet phospholipids. These reorganizations and the subsequent expression of the nonbilayer behavior of PE are proposed to form the basis for sarcolemma destabilization and destruction. Lowering the PE content of myocytes, especially of the sarcolemma, is then expected to attenuate myocyte damage after simulated ischemia or metabolic inhibition. Culturing neonatal rat heart myocytes in the presence of N,N-dimethylethanolamine resulted in the synthesis of the bilayer-preferring N,N-dimethyl-PE and a lowering of the ratio between nonbilayer- and bilayer-preferring phospholipids from 0.58 to 0.30. This change in phospholipid composition did not impair cell functioning but did result in a strong attenuation of cell damage on ischemia or metabolic inhibition. A good correlation between the nonbilayer-preferring phospholipid content and the degree of cell damage was obtained (r = 0.98). These results provide further evidence that physicochemical properties of the sarcolemmal phospholipids play a crucial role in the sarcolemmal disruption during prolonged ischemia and/or reperfusion.

Induction of manganese superoxide dismutase by glucocorticoids in glomerular cells

Our previous in vivo study demonstrated that methylprednisolone (MP) activates glomerular antioxidant enzymes and attenuates glomerular oxidant injuries, including those in experimental nephrosis. The present study investigates the cellular mechanism of the MP-induced activation of antioxidant enzymes and their contribution to the attenuation of cellular oxidant toxicity. When bovine glomerular endothelial cells (GECs) were treated with 10 microM MP, cellular manganese superoxide dismutase (Mn-SOD, 3.95 +/- 0.33 mu/mg protein, M +/- SE) and catalase (1.64 +/- 0.06 k/mg protein) activities were significantly (P < 0.05) elevated above control GECs (2.23 +/- 0.43 mu/mg protein and 1.06 +/- 0.09 k/mg protein, respectively). When GECs pretreated with MP (10 microM 24 hrs) were exposed to xanthine (0.1 mM)+xanthine oxidase (5 mU/ml) for four hours, levels of specific membrane lipid peroxidation products, that is, phosphatidylcholine- and phosphatidylethanolamine-hydroperoxides, remained at levels 10 to 25% of those measured in non-MP-treated (xanthine/xanthine oxidase-exposed) control cells. Moreover, the degree of cell damage following exposure to the superoxide generating system, assessed by 51Cr release, was significantly attenuated in MP-treated cells (approximately 50% of MP-non-treated controls, N = 6). Thus, MP-treated GECs with elevated antioxidant enzyme activities by MP were more resistant to the toxic effect of reactive oxygen metabolites. The mechanism of antioxidant enzyme induction by MP was studied for Mn-SOD. MP was shown to enhance Mn-SOD mRNA in bovine GECs and rat glomerular mesangial cells (GMCs) in dose-dependent manners.(ABSTRACT TRUNCATED AT 250 WORDS)