Lipid peroxidation and antioxidant systems in patients with chronic renal failure

Toxic oxygen-free radicals have been implicated in the pathogenesis of many diseases. Free radicals are thought to be involved in various kidney pathologies, including acut renal failure, glomerulonephritis, and ischemia-reperfusion injury. The progression of chronic renal failure might be bioincompatibility phenomena occuring during extracorporeal circulation in dialysis may induce an oxidative stress. Lipid peroxidation is the biological process leading to cell injury caused by free radicals. Toxic oxygen-free radicals mainly attack the polyunsaturated fatty acids in the membrane producing malonyldialdehyde (MDA), a short chain aldehyde, which is an intermediate product of the oxidation of polyunsaturated fatty acids. The biological effects of these highly reactive oxygen species controlled by antioxidant mechanisms including antioxidant molecules such as vitamin E, vitamin C, ^-Carotene and antioxidant enzymes. Among these antioxidant enzymes, superoxide dismutase (SOD) and glutathione peroxidase (GPx) play a key role. In our study, patient group were included subjects with chronic renal failure undergoing haemodialysis thrice a week (N=40). Control group was selected from healthy subjects (N=40). The blood samples were collected to patients before and after dialysis. Plasma MDA, serum vitamin E, vitamin C ve (3- Carotene and eritrosit SOD, and GPx levels were measured in the blood samples.The MDA levels of patient groups before and after dialysis were found higher than those of control group (p<0.01). Also, vitamin E levels of patient groups before and after dialysis were found higher than those of control group (p<0.01, p<0.05). While fJ-Carotene levels of patient group before dialysis was lower than those of control group (p<0.05), there wasn't found any difference between jî- Carotene levels of patient group after dialysis and those of control group (p>0.05). The vitamin C, SOD and GPx levels of patients before and after dialysis were found lower than those of controls (p< 0.01, p<0.01, p<0.05). There weren't found any significant difference between patient groups of before and after dialysis (p>0.05). The effects on measured blood parameters of patient and control groups of sex, age, quetelet index, smokins status and dialysis age were analyzed statistically. When the patient and control groups were evaluated with respect to other blood parameters, ure and creatinin levels of patient groups were found higher than those of control group (p<0.01). Also, ure and creatinin levels of patient group before dialysis were found higher than those of after dialysis (p<0.01). The total cholesterol, triglyceride, and uric acid levels of patients with chronic renal failure were found higher than those of controls (p<0.01). When albumin, hemoglobin,and total protein levels of patient group were found lower than control group (p<0.01), there wasn't found any difference between total bilirubin levels of patient and control group (p>0.05).-224- There were found correlation between vitamin C and SOD (r =-0.3, p<0.05), MDA and vitamin C (r =-0.3 1, p<0.05), GPx and SOD (r =0.32, p<0.05), vitamin E and cholesterol (r =0.38, p<0.05), vitamin E and triglyceride levels (r =0.42, p<0.01) in patient group after dialysis; vitamin E and SOD (r =0.36, p<0.05) and vitamin C and SOD levels (r =-0.44, p<0.01) in control group. Also, there were found correlation between cholesterol and triglyceride levels in patient and control group (r =0.63, p<0.01 and r =0.34, p<0.05).