High morning blood pressure surge is associated with oxidative stress and paraoxonase 1 activity in newly diagnosed hypertensive patients

Background: Both oxidative stress and morning surge (MS) of blood pressure (BP) were found to be closely related with cardiovascular and cerebrovascular diseases. We investigated the association between MS of BP and oxidative stress in newly diagnosed hypertensive patients. Methods: We prospectively included 237 newly diagnosed hypertensive patients in the present study (mean age: 51.6 +/- 11.7 years). The patients were classified according to the extent of the sleep-through surge as follows: the top decile of sleep-through surge (>47.2 mmHg, n = 27; EMShigh group), versus all others (n = 210, EMSlow group). Total antioxidant capacity (TAC) and total oxidant status (TOS) levels were determined by using an automated measurement method. The oxidative stress index (OSI) was calculated as the ratio of TOS to TAC. Serum paraoxonase 1 (PON-1) activity was measured spectrophotometrically. Results: Patients in EMShigh group were found to have higher hs-CRP, TOS, and OSI values and lower TAC and PON-1 values (p < 0.01, for all). MS of BP was associated with hs-CRP, PON-1, TOS, TAC, and OSI levels in bivariate analysis. Multivariate linear regression analysis showed that MS of BP was significantly associated with PON-1(beta = -0.206, p < 0.001), OSI (beta = 0.602, p < 0.001) and hs-CRP (beta = 0.210, p < 0.001). Conclusion: Present study shows that OSI is increased and antioxidant PON-1 activity is decreased in patients with enhanced MS of BP. There is a close association between high MS of BP and oxidative stress markers in newly diagnosed hypertensive patients.