Lymphocyte DNA damage and total antioxidant status in patients with white-coat hypertension and sustained hypertension

Objectives: We assessed lymphocyte DNA damage and total antioxidant status (TAS) in patients with white-coat hypertension (WCH) and sustained hypertension (SHT).
Study design: The study included 23 patients (14 females, 9 males; mean age 46±6 years) with WCH, 21 patients (13 females, 8 males; mean age 45±7 years) with newly diagnosed SHT, and 19 age- and sex-matched healthy volunteers as controls. All subjects underwent echocardiographic examination, office blood pressure measurements, and 24-hour ambulatory blood pressure monitoring. DNA damage was assessed by the alkaline comet assay in peripheral lymphocytes, and plasma TAS levels were determined using an automated measurement method.
Results: The two hypertensive groups had similar echocardiographic measurements and office systolic and diastolic blood pressures. The mean daytime and nighttime pressures were significantly higher in the SHT group (p<0.05). Patients with WCH had similar daytime and nighttime pressures compared to the controls (p>0.05). Patients with SHT had significantly increased lymphocyte DNA damage (p<0.001, for both WCH and control groups) and decreased TAS level (p=0.012 vs WCH group; p<0.001 vs controls). Patients with WCH did not differ significantly from the control group with regard to lymphocyte DNA damage (p=0.052), but had significantly lower TAS levels (p<0.001). In the SHT group, lymphocyte DNA damage was correlated with TAS (r= -0.818, p<0.001), age (r=0.453, p=0.039), total cholesterol (r=0.550, p=0.010), and LDL-cholesterol (r=0.539, p=0.012). In multiple linear regression analysis, lymphocyte DNA damage was independently correlated with serum TAS level (ß= -0.717, p<0.001). In the WCH group, lymphocyte DNA damage was only correlated with serum TAS level (r= -0.458, p=0.028).
Conclusion: Decreased TAS showing increased oxidative stress and increased lymphocyte DNA damage may contribute to target organ damage in patients with WCH.

Keywords: Antioxidants/metabolism, blood pressure, blood pressure monitoring, ambulatory; DNA Damage; hypertension; lymphocytes; oxidative stress.