Esin Öztürk

Oxidative stress in white coat hypertension; role of paraoxonase.

Oxidative stress in sustained hypertension was shown with several biochemical parameters. Oxidized low-density lipoprotein (oxLDL) plays an important role during the atherosclerosis process and paraoxonase (PON1) can significantly inhibit lipid peroxidation. Serum PON1 activity, oxLDL and malondialdehyde (MDA) concentrations and their relationship with serum lipid parameters and systolic and diastolic blood pressures (SBP and DBP) were determined in subjects with white coat hypertension (WCH), sustained hypertension (HT) and normotension (NT). The study group consisted of a total of 86 subjects, 30 with WCH (14 male, 16 female subjects), 30 with HT (13 male, 17 female subjects) and 26 with NT (12 male, 14 female subjects). Both white coat hypertensive and hypertensive subjects had significantly higher levels of MDA than normotensives (P<0.026 and P<0.001, respectively). The oxLDL level of the HT group was significantly higher than the NT group (P<0.023). The WCH group had an oxLDL level similar to both hypertensive and normotensive groups. HT and WCH groups had significantly lower PON1 levels than the normotensive group (P<0.001). oxLDL correlated with MDA positively (P=0.008), and PON1 negatively (P=0.008). A negative correlation between MDA and PON1 (P=0.014) was detected. MDA correlated positively with both SBP and DBP (P=0.001), while PON1 correlated with both of them negatively (P=0.01 and P=0.008, respectively). OxLDL correlated with diastolic blood pressure positively (P=0.008). Our data demonstrate that oxidative stress increase in WCH is associated with a decrease in PON1 activity. The reduction in PON1 activity may be one of the factors leading to an increase in oxidative status in WCH.

Target organ damage and changes in arterial compliance in white coat hypertension. Is white coat innocent

The aim of this study was to perform an extensive evaluation of target organ status, metabolic abnormalities and hemodynamic alterations in white coat hypertension (WCH). Fifty normotensive (NT), 90 WCH (ambulatory daytime blood pressure <135/85 mmHg) and 101 hypertensive (HT) subjects underwent extensive biochemical, echocardiographic, fundoscopic examination. In a subgroup study, arterial compliance and intima‐media thickness (IMT) were measured by Doppler ultrasound in left common carotid artery. WCH subjects were found to have higher body mass index (BMI) than the NTs (p = 0.042). Left ventricle mass index (LVMI) was greater in the WCHs than the NTs (p < 0.001), but significantly less than the HTs (p < 0.001). Hypertensive retinopathy was observed in the WCHs, but was less severe and rare compared to the HTs (13% vs 27 %). Both WCHs and HTs had high levels of urinary albumin excretion (UAE) (p = not significant). Total cholesterol was higher in WCHs than in the NTs (p = 0.04) The distensibility coefficient (DC) of the WCHs was significantly greater than the HTs (p < 0.01), while significantly smaller than the NTs (p < 0.01). The compliance coefficient (CC) of the WCHs was significantly higher than the HTs (p < 0.01), and significantly less than the NTs (p < 0.01). The IMT in the HTs was significantly higher than the WCHs (0.81 ± 0.05 vs 0.70 ± 0.04 mm; p < 0.001) and the NTs (p < 0.001). The difference between the NTs and the WCHs was not significant. Our data indicate that patients with WCH represent an intermediate group between NTs and sustained HTs where target organ damage and cardiovascular risk is concerned.

Endothelium and angiogenesis in white coat hypertension.

Hypertensive patients are at particular risk of cardiovascular complications, possibly related to endothelial damage or dysfunction, or to abnormal angiogenesis. The aim of this study was to compare the risk conferred by white coat hypertension (WCH) vs sustained hypertension in the development of the endothelial dysfunction and abnormal angiogenesis by evaluating nitric oxide (NO=NO2+NO3), endothelin-1 (ET-1), vascular endothelial growth factor (VEGF), and E-selectin levels in plasma. The study group included 102 subjects, 34 with WCH (17 male and 17 female patients) aged 49±11 years, 34 sustained hypertensives (HT) (15 male and 19 female patients) aged 47±11 years and 34 normotensive control subjects (NT) (16 male and 18 female patients) aged 48±10 years. WCH was defined as clinical hypertension and daytime ambulatory blood pressure less than 135/85 mmHg. The subjects were matched for age, gender, body mass index and the patients with smoking habit, dyslipidaemia, and diabetes mellitus were excluded from the study. The NO, ET-1, VEGF and E-selectin levels were analysed by ELISA technique. The WCH subjects had significantly higher levels of NO than the HT (41.68±2.23 vs 32.18±2.68 μmol/l; P<0.001) and significantly lower values than the NT (48.24±4.29 μmol/l; P<0.001). ET-1 levels of the WCH group were significantly higher than the NT (8.10±0.92 vs 5.95±0.26 ng/ml; P<0.001) and significantly lower than the HT (11.46±0.59 ng/ml; P<0.001). Considering with VEGF, the WCH group had significantly higher levels than the NT (195.88±11.84 vs 146.26±18.67 pg/ml; P<0.001), but the difference from the HT group was not significant (203.35±7.48 pg/ml; P=0.062). E-selectin in the WCH group was significantly lower than the HT (4.77±0.52 vs 8.49±2.85; P<0.001), but the difference from the NT group was not significant (3.86±0.67; P=0.077). Our data demonstrate that WCH is associated with endothelial dysfunction and abnormal angiogenesis. The degree of these changes is not as severe as observed in hypertensive population.

The antihypertensive effects of doxazosin on the arterial system: changes in peripheral vascular resistance and wall tension

Background: Hypertension is characterized by structural and functional abnormalities that affect the entire cardiovascular system, including the large arteries. The antihypertensive efficacy of doxazosin, a selective alpha(1) antagonist, and its effects on the arterial system were investigated. Method: In our double-blind, randomized, placebo-controlled study including 30 hypertensive patients (doxazosin group: nine males, 11 females; mean age 45+/-12 years; placebo group: four males, six females; mean age 47+/-9 years), the systolic, diastolic and mean blood pressure (BP), heart rate, diameter and area of the brachial artery, peak systolic velocity, end-diastolic velocity, pulsatility index (PI), resistance index (RI), S/D (systolic velocity/diastolic velocity), flow volume, local resistance, and wall tension were recorded before and 4 h after the administration of 2 mg doxazosin or placebo. The two groups were statistically compared. Results: In the doxazosin group, systolic, diastolic and mean pressures decreased significantly (P<0.001), while heart rate remained unchanged. Local resistance (P<0.001), RI (P<0.05), PI (P<0.05), and wall tension (P<0.001) all decreased significantly, while flow volume increased significantly (P<0.05). However, no significant changes were observed in arterial diameter, surface area, peak systolic velocity, end-diastolic velocity or S/D ratio. The placebo group did not show a significant difference in any of the parameters listed above. Conclusion: The antihypertensive effect of doxazosin is accompanied by a reduction in brachial arterial wall tension that occurs without any change in arterial diameter. The lack of change in the diameter of the artery leads us to suggest different effects on other vasomotor determinants.