Measurement of Malondialdehyde as a Biomarker of Lipid Oxidation in Fish

Oxidative reactions are key part of the stress response in marine organisms, which are exposed to a wide variety of environmental stressors. Lipid peroxidation (LPO) occurs in response to oxidant attack, giving rise to unsaturated aldehydes as malondialdehyde (MDA), the main biomarker for LPO assessment. Levels of MDA are measured in biological samples of different fish matrices to determine the oxidative effect of physical or chemical agents, particularly represented by metals. The most used assay is the spectrophotometric determination of thiobarbituric acid (TBA) as MDA-TBA2 adduct. Selectivity is enhanced by separating the adduct by chromatographic methods such as high-performance liquid chromatography or by using alternative derivatization reagents. Because, in biological organism, MDA is found free or protein bound, the two forms should be measured, and the extraction procedures are a crucial step in the processing of the biological sample. This review focused on MDA determination procedures used to assess the effect of experimental and environmental stress induced in fish.

Evaluation of Plasma Malondialdehyde among Sudanese Type 2 Diabetic Patients

Background and objectives: Diabetes is a chronic multifactorial disease which requires a variety of strategies to reduce its epidemic. Type 2 diabetes (T2MD) is the most common form of diabetes which results from inefficiency of insulin secretion or resistance to insulin action, both of which lead to chronic hyperglycemia. Lipid peroxidation is an oxidative stress process that involve in T2DM complications. This study aimed to 1) determine plasma malondialdehyde (MDA) levels as a biomarker for lipid peroxidation in Sudanese patients with T2DM, and 2) assess the associations between MDA and diabetes-related variables. Material and Methods: This case-control study was conducted from November 2022 to June 2023 at the National University, Sudan. It included 100 participants, of whom 50 were T2DM patients and 50 were healthy controls. Data on demographics, clinical characteristics, and biochemical markers (FBS, HbA1c, and MDA) were collected. The NycoCard HbA1c method and the GOD-POD Method were used for HbA1c and glucose measurement, respectively. MDA was determined by the thiobarbituric acid reactive substances method. The data were analyzed using SPSS Version. Results: Significant differences were observed between T2DM patients and healthy controls in FBS (P = 0.000), HbA1c (P = 0.000), and MDA (P = 0.010), with T2DM patients exhibiting higher levels. The study revealed a strong positive correlation between MDA levels and the duration of diabetes (r = 0.69, P = 0.00), while other variables, including age, BMI, and glucose control, did not significantly correlate with MDA levels. Conclusion: Findings revealed elevated MDA levels in Sudanese T2DM patients, with a positive correlation between MDA and diabetes duration. These findings emphasize the importance of oxidative stress in T2DM pathogenesis and call for the need for targeted strategies to mitigate oxidative damage and improve diabetes care.

The Comparison of Contents of Malondialdehyde and Proline in the Area of Karst Area in Northweastern Guangxi Province

[Objective] To select excellent pioneer species of better ecological and economical comprehensive benefits from the common rock hill plants in Karst area in northwestern Guangxi Province.[Method] Determine the contents of malondialdehyde and proline in leaves of 65 strains of plants by thiobarbituric acid method and sultosalicylic acid method,analyze the relevance of the contents of malondialdehyde and proline by mathematics statistics and analyze the 65 kinds of rock hill plants by clustering [Result] The contents of malondialdehyde and proline are 0.005 2-0.038 1 μmol/g.There are comparably significant differences in the contents of malondialdehyde in different plants;The determination of proline contents in plant＇s leaves are 4.347-374.956 μg/ml.There are also significant differences in proline of different leaves of rock hill plants.The contents of malondialdehyde and proline can be used as a reference point in selecting pioneer plants in Karst area.But when we select the pioneer plants,not only the biological characters of the species themselves should be taken into consideration,but also the differences of Karst area environment,ecological and biological benefits and the reasonable distribution of species.[Conclusion] Pistacia chinensis,Zenia insignis,Acacia confusa,Itoa orientalis and Sophora japonica can be used as the first choices of excellent pioneer plants in Karst area in northwestern area which comparably consists with the real situation of afforestation of rock hills and recovery of plants in Guangxi.

Mapping of QTLs for Leaf Malondialdehyde Content Associated with Stress Tolerance in Rice

Malondialdehyde （MDA） is the final product of lipid peroxidation, and MDA content can reflect the stress tolerance of plants. To map QTLs conditioning the MDA content in rice leaves, a recombinant inbred line （RIL） population with 247 lines derived from an indica-indica cross Zhenshan 97BxMilyang 46, and a linkage map consisting of 207 DNA markers were used. The RIL population showed a transgressive segregation in the MDA content of rice leaves. Two QTLs for the MDA content in rice leaves were detected in the intervals RG532-RG811 and RG381-RG236 on chromosome 1, with the additive effects from maternal and paternal parents, accounting for 4.33% and 4.62% of phenotype variations, respectively.

Changes of c-fos, Malondialdehyde and Lactate in Brain Tissue after Global Cerebral Ischemia under Different Brain Temperatures

Summary： Under global cerebral ischemia, the effect of different brain temperature on cerebral ischemic injury was studied. Male Sprague-Dawley rats were divided into normothermic （37-38℃） ischemia, mild hypothermic （31 32℃） ischemia, hyperthermic （41-42℃） ischemia and sham-operated groups. Global cerebral ischemia was established using the Pulsinelli four-vessel occlusion model and brain temperature was maintained at defined level for 60 min after 20omin ischemia. The expression of c-fos protein and the levels of malondialdehyde （MDA） and lactate in brain regions were detected by immunochemistry and spectrophotometrical methods, respectively. C-fos positive neurons were found in the hippocampus and cerebral cortex after cerebral ischemia reperfusion. Mild hypothermia increased the expression of c-fos protein in both areas, whereas hyperthermia decreased the expression of c-los protein in the hippocampus at 24 h reperfusion, and the cerebral cortex at 48 h reperfusion when compared to normothermic conditions. In normothermic, mild hypothermic and hyperthermic ischemia groups, the levels of MDA and lactate in brain tissue were increased at 24, 48 and 72 h reperfusion fol- lowing 20-min ischemia as compared with the sham-operated group （P〈0.01）. The levels of MDA and lactate in mild hypothermic group were significantly lower than those in normothermic group （P〈0.01）. It is suggested that brain temperature influences the translation of the immunoreactive protein product of c-fos after global cerebral ischemia, and MDA and lactate are also affected by hypothermia and hyperthermia.

Changes in Antioxidant Enzyme Activities and Malondialdehyde(MDA) Content of Rice with Blast Resistance Induced by Ag-antibiotic 702

The paper was to explore the effect of rice blast resistance induced by Ag-antibiotic 702 on antioxidant enzyme activities and malondialdehyde（ MDA）content. At three-leaf and one-heart stage of Luliangyou 996,15 μg/mL Ag-antibiotic 702 was sprayed,while Validamycin and distilled water were sprayed as positive control and negative control,respectively. The antioxidant enzyme（ SOD,POD,PPO,CAT and PAL） activities and malondialdehyde（ MDA） content in rice leaves were determined every 24 h within 168 h post spraying. Compared with CK,the MDA content and activities of the five antioxidant enzymes increased in Agantibiotic 702 treatment,Validamycin treatment and M. grisea inoculation treatment. The MDA content and SOD,CAT and POD activities in Ag-antibiotic 702 treatment were significantly higher than those in M. grisea inoculation treatment in early stage,and the APX and LOX activities increased more remarkably and rapidly. The induction effect of Ag-antibiotic 702 could reach or exceed that of Validamycin treatment. Ag-antibiotic 702 enhanced the resistance to rice blast because MDA content and antioxidant enzymes activities were improved in rice leaves. Therefore,the increase of rice blast resistance induced by Ag-antibiotic 702 in rice was positively correlated with the increase of MDA content and antioxidant enzymes activities in rice leaves.

Increased plasma malondialdehyde and fructosamine in anemic H pylori infected patients:Effect of treatment

AIM： TO unravel the possible association of malondialdehyde （MDA） and fructosamine in anemic H pylori infected patients and to observe the alteration in MDA and fructosamine levels in these patients after treatment for one month. METHODS： Fructosamine, MDA and glucose were estimated in 22 anemic H pylori infected patients and 16 healthy controls. Hematological parameters were also evaluated in both the groups using Sysmex-K-100 automated cell counter. The H pylori infected patients were randomly divided into two groups. Hpylori infected patients in Group Ⅰ received both iron supplementation and anti-H pylori therapy, while patients in Group Ⅱ received only iron supplementation. All the biochemical and hematological parameters were estimated after one month of treatment. RESULTS： In anemic H pylori infected patients, while MDA （5.41 ± 2.16 vs 2.26 ± 0.50; P 〈 0.05） and fructosamine （2.64 ± 0.93 vs 1.60 ± 0.35; P 〈 0.05） were significantly increased, iron （32.72 ± 14.93 vs 110.25 ± 26.58; P 〈 0.05）, hemoglobin （6.9 ± 2.6 vs 12.66 ± 0.74; P 〈 0.05） and ferritin （28.82 ± 16.27 vs 140.43 ± 30.72; P 〈 0.05） levels were significantly decreased compared with the controls. With partial correlation analysis, fructosamine was found to have a significant positive correlation with MDA. In Group I, while MDA level decreased significantly （3.11 ± 1.73 vs 5.50 ± 2.46; P 〈 0.05）, there was a significant increase in iron （84.09 ± 29.51 vs 36.09 ± 17.81; P 〈 0.05）, hemoglobin （10.40 ± 1.11 vs 7.42 ± 1.90; P 〈 0.05） and ferritin （116.91 ± 63.34 vs 30.46 ± 17.81; P 〈 0.05） levels after one month. There was no significant change in the levels of fructosamine in group Ⅰ after treatment. Similarly, no significant alterations were noted in the levels of IDA, fructosamine, hemoglobin or ferritin in Group Ⅱ patients after one month of treatment. CONCLUSION： An increased level of fructosamine and MDA was found in anemic H pylori infected patients. Present data supports the premise that lipid peroxides per se do play a role in the glycation of plasma proteins. Furthermore, the findings from this study indicate that treatment for both anemia and H pylori infections is required for lowering the levels of lipid peroxides in these patients.

Effect of in ovo ghrelin administration on serum malondialdehyde level in newly-hatched chickens

Objective:To investigate effects of in ovo ghrelin administration on serum malondialdehyde(MDA)level in newly-hatched chickens.Methods:Fertilized eggs were divided into 7 groups:group Tl as control(without injection),group T2(in ovo injected with 50 ng/egg ghrelin on day 5),group T3(in ovo injected with 100 ng/egg ghrelin on day 5),group T4(in ovo injected with 50 ng/egg ghrelin on day 10),group T5(in ovo injected with 100 ng/egg ghrelin on day 10),group T6(in ovo injected with solvent:1%acetic acid,without ghrelin on day 5)and group T7(in ovo injected with solvent without ghrelin on day 10).After hatching,serum MDA concentrations were determined.Results:Chrelin administrated groups(T2,T3,T4 and T5)had lower serum MDA level in comparison with control group(T1)or solvent injected groups(T6 and T7).T2 and T3(ghrelin injection on day 5)had significantly lower MDA concentrations(4.10 and 4.60 nmol/mL,respectively)in comparison with other groups.In T4 and T5,MDA levels were lower than T1,T6 and T7(non-ghrelin administrated groups)(9.53 and 9.50 in comparison with 10.73,10.03 and 10.13 nmol/mL)and were higher than T2and T3.Conclusions:It can be concluded that in ovo administration of ghrelin can have antioxidative protection and reduce serum MDA level.Ghrelin administration on day 5 of incubation is more efficient.

Regulation of Content of Malondialdehyde by Siqi Decoction via Increasing Activity of Superoxide Dismutase in Blood Serum of Rats with Myocardial Ischemia

Effect of Siqi decoction on myocardial ischemia is to prevent cardiac myocyte membrane from damage associated with oxygen free radicals related to NO. To research the regulatoin of the content of malondialdehyde by Siqi decoction, an index of lipid peroxidation, via increasing activity of superoxide dismutase in blood serum of rats with Myocardial Ischemia, the model of myocardium ischemia was made in Wistar rats with posterior pituitary injection through vein in tail. Siqi decoction, Diaoxinxuekang（DK） and Fufangdanshenpian（FD）, the latter two drugs of which are effective TCM drugs of anti-myocardial ischemia at present, were administrated to the rats with myocardium ischemia for 5 days to compare the effect of them on myocardium ischemia as reference drugs via measuring the changes of the content of malondialdehyde and the activity of superoxide dismutase in the rat blood serum with myocardial ischemia. There were a remarkable increase in the activity of superoxide dismutase and a decrease in the content of malondialdehyde in the serum of the rats administered Siqi decoction compared with those of the rats in control group, p〈0.05. The contents of MDA in the serum of the prevention group rats in the experiments are lower than those of the cure group rats. Anti-Myocardium Ischemia mechanism of Siqi decoction is the regulation of the content of malondialdehyde via increasing activity of superoxide dismutase in the serum of Rats with myocardial ischemia and stimulating the activity of NOS in serum so as to increase NO concentration.

αB-crystallin malondialdehyde,superoxide dismutase, and lutathione peroxidase changes in X-ray irradiated rat lens

AIM: To evaluate αB-crystallin malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GPx) changes in X-ray irradiated rat lens. METHODS: Eight-week-old Sprague-Dawley male rats received X-ray irradiation to the head with rest of the body protected. The exposure dose ranged from 2 to 25 Grays (Gy). The cataract status were examined by slit lamp and rated with 'four-grade systems' post-irradiation. The lens MDA level, and the activities of SOD and GPx were measured in a short-term experiment post-irradiation, and αB-crystallin protein levels were quantified. RESULTS: The lenses of normal control and the X-ray irradiated groups with the dose up to 10 Gy remained transparent throughout the experiment. The lens first appeared tiny scatters, and even lamellar opacities in the posterior capsule 45 days post-irradiation with the dose of 15 Gy, and progressed slowly to the advance stage of cataract; while, for the higher dose (25 Gy), the opacity of lens appeared much earlier, and progressed more rapidly to mature stage of cataract within 1 month. At the end of the observation (90 days post-irradiation), almost all lenses became complete opacity with the higher dose (25 Gy). The degree of lens opacity was rated accordingly. The lens MDA level was increased, and SOD and GPx activities were decreased with a dose-dependent manner post-irradiation. The αB-crystallin protein level was decreased dose-dependently at the end point of observation. CONCLUSION: Oxidative events and αB-crystallin may play important roles in the pathogenesis of cataract in X-ray irradiated rat lens.

Protective effect of melatonin against multistress condition induced lipid peroxidation via measurement of gastric mucosal lesion and plasma malondialdehyde levels in rats

AIM： To study the protective effect of a natural antioxidant, melatonin, against multistress condition induced lipid peroxidation v/a determination of gastric damage and plasma malondialdehyde （MDA） level by high performance liquid chromatography in rats. METHODS： We compared indomethacin-induced gastric damage and MDA plasma level in three groups of rats： unoperated, bile duct ligated and sham-operated and evaluated the role of the melatonin on gastric damage and plasma MDA level. Indomethacin and melatonin were injected intraperitoneally in doses of 50 mg/kg and 20 mg/kg, respectively. Animals were killed 4 h after indomethacin injection. RESULTS： Indomethacin induced more severe gastric damage and plasma MDA level in bile duct ligated animals was significantly higher （3.1±0.04 μmol/L） than sham （2.8±0.04 μmol/L） and unoperated animals （1.4±0.08 μmol/L）. Pretreatment with melatonin reduced indomethacin-induced gastric damage and plasma MDA level. CONCLUSION： Considering the results of this study, we suggest that in multistress conditions the intensity of gastric damage and the plasma MDA level are great and melatonin reduces the negative effect of lipid peroxidation and cell damage by oxidative stress in multistress conditions due to its antioxidizing activity.

Variations of antioxidant enzyme activity and malondialdehyde content in nemertean Cephalothrix hongkongiensis after exposure to heavy metals

The antioxidant enzyme activity and malondialdehyde(MDA) content of Cephalothrix hongkongiensis were studied to assess variations in the biochemical/physiological parameters of nemerteans under heavy metal stress.Worms were exposed to copper,zinc and cadmium solutions at different concentrations,and the activity of three antioxidant enzymes,catalase(CAT),superoxide dismutase(SOD),and glutathione peroxidase(GPX),and MDA content were measured.The results show that the activity of each enzyme changed immediately after exposure to heavy metals.CAT was invariably inhibited throughout the experimental period,while the SOD activity was significantly elevated by exposure to Cu^(2+) for 48h,but then decreased.SOD was inhibited by Zn^(2+) during the first 12h of exposure,but activated when exposed for longer periods.Under Cd^(2+) stress,SOD activity decreased within 72h.GPX activity varied greatly,being significantly increased by both Cu^(2+) and Zn^(2+),but significantly inhibited by Cd^(2+) in the first 12-24h after exposure.MDA content increased on Cu^(2+) exposure,but normally decreased on Zn^(2+) exposure.MDA content followed an increase-decrease-increase pattern under Cd^(2+) stress.In conclusion,the antioxidant system of this nemertean is sensitive to heavy metals,and its CAT activity may be a potential biomarker for monitoring heavy metal levels in the environment.

Increased serum nitric oxide and malondialdehyde levels in patients with acute intestinal amebiasis

Objective:To determine the level of oxygen-nitrogen stress parameters in the pathogenesis of amebiasis.Methods:Twenty-four acute intestinal amebiasis patients and 20 healthy controls were enrolled in the present study.Serum malondialdehyde and nitric oxide levels were determined spectrophotometrically.Results:Serum raalondialdehyde and nitric oxide levels were significantly higher in acute intestinal amebiasis patients than healthy controls(P<0.00l). Conclusions:These results suggest that oxidative and nitrosative stress may play a major role in tissue damage in acute intestinal amebiasis patients.Also these parameters can be used to supplement the conventional microscopic method for reliable diagnosis of intestinal amebiasis.

Effects of melatonin on changes in cognitive performances and brain malondialdehyde concentration induced by sub-chronic coadministration of chlorpyrifos and cypermethrin in male Wister rats

Objective:To evaluate the ameliorative effect of melatonin on sub-chronic chlorpyrifos(CPF)and cypermethrin(CYP)-evoked cognitive changes in male Wistar rats.Methods:Fifty adult male Wistar rats,divided into five groups of ten rats each,were used for the study.GroupsⅠandⅡwere given distilled water and soya oil(2 ml/kg)respectively.GroupⅢwas administered with melatonin at 0.5 mg/kg only.GroupⅣwas administered with CPF[7.96 mg/kg(1/10th LD_(50))]and CYP[29.6 mg/kg(1/10th LD_(50))].and Group V was administered with CPF[7.96 mg/kg(1/10th LD_(50)]and CYP[29.6 mg/kg(1/10th LD_(50)]30 min after melatonin(0.5 mg/kg).The regimens were administered by gavage once daily for 12 weeks.Thereafter,cognitive performances were determined and the brain was evaluated for malonaldehyde concentration.Results:CPF and CYP induced cognitive deficits and increased brain malonaldehyde concentration,which were all ameliorated by melatonin.Conclusion:Cognitive deficits elicited by CPF and CYP was mitigated by melatonin due to its antioxidant property.

Significance of malondialdehyde concentration in seminal plasma of infertile men

Objective: To determine the concentration of malondialdehyde (MDA), product of lipid peroxidation, in seminal plasma and evalu ate its significance. Methods: Ninety-three cases of infertile pa tients were divided into the obstructive azoospermic (12 cases), the non-obstructive azoospermic (15 cases), the oligozoospermic (21 cases), the asthenozoospermic (19 cases), the oligoastheno zoospermic (16 cases) and the oligoasthenoteratozoospermic (10) groups. Eighteen fertile males served as the controls. MDA con centration was assessed by high-performance liquid chromatogra phy (HPLC). Results: With the exception of the obstructive azoospermic group, the MDA concentration in the seminal plasma was significantly different between the control group and the infer tile groups (P<0.01) as well as between the different infertile groups. Conclusion: Determination of MDA concentration in the seminal plasma is helpful to the diagnosis of male infertility induced by overproduction of reactive oxygen species.

Changes of peroxide dismutase activity and malondialdehyde level in the smooth muscle cells of human fetal aorta cultured in vitro by low density lipoprotein conditional medium

Here are reported the changes of superoxide dismutase(SOD)activity andmalondialdehyde(MDA)in the smooth muscle cells of human fetal aorta cultured in vitro with lowdensity lipoprotein(LDL)conditional medium.The results showed that a single concentration of hu-man LDL(50μg/ml)stimulated proliferation of smooth muscle cells,and the SOD activityof the cells in the experimental group was higher,from the first to the fifth cultured day whenthe cells had a active proliferation,than that of the control cells.This suggests that LDL might in-duce the increase of SOD activity.At the seventh day,as the cells were in inactive proliferation,SOD activity was low and the difference was significant as compared with that at the fifth day ofthe same group.This also indicates that the SOD activity may be related to the cell proliferation.MDA level within the cells of the esperimental group was lowered with the cell active proliferationand the increase of SOD activity,but when the cells were in inactive proliferation and the SOD ac-tivity decreased,it will remained low.

Effects of basic fibroblast growth factor on superoxide dismutase activity and malondialdehyde content in the rat brain following intracerebral hemorrhage

BACKGROUND： Studies have confirmed that basic fibroblast growth factor （bFGF） promotes neuronal survival and neurite outgrowth. OBJECTIVE： To compare and verify the effects of bFGF on superoxide dismutase activity and malondialdehyde content in rat brain tissues surrounding a hemorrhagic lesion, as well as the hippocampus at the hemorrhagic side. DESIGN, TIME AND SETTING： The randomized, controlled, neurobiological study was performed at the Science Experimental Center and Research Laboratory, Guangxi Medical University, China, from September to December 2006. MATERIALS： Ninety-two adult, healthy, Wistar rats of equal gender were used to establish intracerebral hemorrhage by infusing type VII collagenase into the left internal capsule. Type Ⅶ collagenase （Sigma, USA）, superoxide dismutase and malondialdehyde kits （Jiancheng, China）, and bFGF （Institute of Bioengineering, Ji＇nan University, China） were used for this study. METHODS： Ninety successfully lesioned rats were equally and randomly divided into three groups. Rats in the bFGF group were intramuscularly injected daily with bFGF （8 ug/kg）. Rats in the saline control group received an equal volume of saline. The rats in the model group did not receive other interventions. Superoxide dismutase activity was measured using the xanthine oxidase method. Malondialdehyde contents were detected using the thiobarbituric acid method. MAIN OUTCOME MEASURES： At 1, 3, and 7 days following intracerebral hemorrhage, superoxide dismutase and malondialdehyde were determined in the brain tissue surrounding the hematoma and in the hippocampus in the affected hemisphere. RESULTS： In brain tissue surrounding the hematoma, superoxide dismutase activity was significantly increased in the bFGF group at 3 and 7 days after intracerebral hemorrhage compared with the saline control group, whereas malondialdehyde content was significantly decreased （P 〈 0.05）. In the hippocampus, superoxide dismutase activity was significantly increased in the bFGF group at 7 days following intracerebral hemorrhage compared with the saline control group, whereas malondialdehyde content was significantly decreased （P 〈 0.05）. At 1, 3, and 7 days after intracerebral hemorrhage, there was no significant difference between the saline control group and the model group with regards to parameter or brain region （P 〉 0.05）. CONCLUSION： Increased superoxide dismutase activity and decreased malondialdehyde content were detected in tissue surrounding the hematoma, as well as the ipsilateral hippocampus, of intracerebral hemorrhage rats treated with bFGF. Changes in these parameters were detected earlier in tissue adjacent to the lesion, compared with the ipsilateral hippocampus.

Changes in Urinary Metabolomics of Female Kashin-Beck Disease Patients in Qinghai-Tibet Plateau,China

Kashin-Beck disease(KBD)is a chronic,endemic,degenerative osteoarthropathic condition that is predominantly found in China's Mainland.KBD is a progressive disease,and the signs and symptoms become more severe in adulthood owing to the continuous development of lesions in the joint cartilage[1].Although childhood KBD has largely been controlled,adult KBD is an important health concern in rural regions.Unfortunately,in the last century,many adult KBD patients still remain during serious epidemics.

Physicochemical variations of malondialdehyde－and Cu^（2＋）－modified low density lipoprotein

After Modification of low density lipoprotein(LDL) by either malondialdehyde(MDA) or Cu2+,its thiobarbituric acid reactive substances(TBARS),lipid conjugated dienes,and relative electrophoretic mobility(REM) levels,and the fluorescence emission spectra we

Changes in activity of superoxide dismutase and content of malondialdehyde in rats with monocrotaline-induced pulmonary hypertension

To observe changes in activity of superoxide dismutase (SOD) and content of malondialdehyde (MDA) in rats with monocrotaline-induced pulmonary hypertension. Methods: Adult ma1e Sprague-Dawley rats were given a single subcutaneous injection of monocrotaline (MCT, 60 mg/kg) for modeling PH. Activities of SOD and contents of MDA in plasma and pulmonary homogenate were measured by colorimetric analysis. The thickness of the media of pulmonary arterioles (external diameter <100μm) was measured using colour image analysis system. Results: Four weeks after injection of MCT, activities of SOD in venous plasma and pulmonary homogenate for MCT group were 106±45 NU/ml (P<0.05) and 317±59 NU/ml (P<0.01) respectively, whileactivities of SOD for control group were 159±28 NU/ml (P<0.05) and 505±47 NU/ml (P<0.01) respectively.COntents of MDA in venous plasma and pulmonary homogenate for MCT group were 15±5 and 59±14 μmol/L,while contents of MDA for control group were 5. 3±2. 8 and 32±19 ±mol/L. The thickness of the media of pulmonary arterioles increased significantly. Conclusion: The primary cause of PH is the injury of pulmonary vascular endothelial cells by MCT, which decreases the O2 removing ability of the lungs but increases lipid peroxidation,thus inducing PH.