Relationship between high density lipoprotein antioxidant activity and carotid arterial intima-media thickness in patients with essential hypertension.

The objective of this study was to evaluate high-density lipoprotein (HDL) antioxidative activity and its possible influencing factors in patients with essential hypertension and to investigate the correlations between HDL antioxidative activity and the carotid arterial intima-media thickness (CIMT). Thirty-three patients with essential hypertension and 32 healthy people as control were included. High- and low-density lipoprotein in plasma were isolated by one-step density gradient ultracentrifugation, and induced oxidation with external Cu(2+). Antioxidant activity of HDL, lag time, and lipid peroxidation degree were determined by spectrophotometric and thiobarbituric acid reactive substances (TBARS) methods. Paraoxonase 1 (PON1) activity in serum was measured with continuous monitoring using phenylacetate as a substrate. The CIMT was measured with a high-resolution ultrasound Doppler system. In patients with essential hypertension, the inhibitory effect of HDL on low-density lipoprotein (LDL) oxidation and the PON1 activity were reduced (72.29 +/- 2.03)% vs. (80.91 +/- 2.06)%, and (112.21 +/- 8.64)u/ml vs. (146.43 +/- 8.79)u/ml (all P < 0.05). The lag time of oxidation and the lipid peroxidation between the hypertensive group and the control group did not show a statistically significant difference. Multiple stepwise regression analysis revealed that HDL antioxidative activity might be affected by PON1 activity (P = 0.004), diastolic pressure (P = 0.004), sex (P = 0.006), and that CIMT might be affected by HDL antioxidative activity (P = 0.030), systolic pressure (P = 0.026), and total cholesterol level (P = 0.033). The HDL antioxidative activity is reduced in patients with essential hypertension and significantly affected by sex. The CIMT was negatively correlated with HDL antioxidative activity, which suggests that decreased HDL antioxidative activity may be one of the important determinants for the development of atherosclerosis in patients with essential hypertension.