engleski

SERUM PARAOXONASE ACTIVITY AND CONCENTRATION OF HDL, HDL2 AND HDL3 IN HEMODIALYZED PATIENTS

Paraoxonase 1 (PON1) is a calcium-dependent esterase, synthesized in the liver and secreted into the plasma where it is associated with HDL. The presence of PON1 in HDL may be a major contributor to the antiatherogenicity of this lipoproteine because PON1 inhibits the oxidative modification of LDL. PON1 activity reduction in patient undergoing haemodialysis is probably caused by lower HDL concentration and altered HDL subfraction distribution. We carried out this study in order to determine concentration of total HDL, HDL2 and HDL3, and PON1 activity that is associated with HDL fractions in patients with chronic renal failure undergoing haemodialysis (N=71), and control subjects (N=88). Paraoxonase activity was assayed spectrophotometrically with paraoxon as a substrate and in presence of NaCl. For isolation of total HDL and HDL3 we used precipitation with polyethylene glycol. Concentration of HDL and HDL3 was determined using CHOD-PAP method. HDL2 concentration was calculated as difference between HDL and HDL3 concentration. Serum PON1 activity and concentration of total HDL, HDL2 and HDL3 fractions was significantly reduced in patients with chronic renal failure (P<0.001). PON1 activity in isolated total HDL and HDL3 fraction was also decreased in patients group (P = 0.001 ; P< 0.001). Standardized PON1 activity to total HDL and HDL3 concentration did not differ between two examined groups (P = 0.557 for PON1/HDL and P = 0.197 for PON1/HDL3). Percentages of HDL3 and HDL2 fractions were very similar in control group (67.42% HDL3 and 32.25 % HDL2) and in group of patients with chronic renal failure (65.22 % HDL3 and 30.43 % HDL2). Our results suggest that reduction in PON1 activity in our patient group is caused by lowerof total HDL concentration which causes a decrease of both fractions of HDL.

Paraoxonase1; HDL; HDL2; HDL3

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