Essential Hypertension and Oxidative Stress: Novel Future Perspectives

Abstract

Among cardiovascular diseases, hypertension is one of the main risk factors predisposing to fatal complications. Oxidative stress and chronic inflammation have been identified as potentially responsible for the development of endothelial damage and vascular stiffness, two of the primum movens of hypertension and cardiovascular diseases. Based on these data, we conducted an open-label randomized study, first, to evaluate the endothelial damage and vascular stiffness in hypertense patients; second, to test the effect of supplementation with a physiological antioxidant (melatonin 1 mg/day for 1 year) in patients with essential hypertension vs. hypertensive controls. Twenty-three patients of either gender were enrolled and randomized 1:1 in two groups (control and supplemented group). The plasmatic total antioxidant capacity (as a marker of oxidative stress), blood pressure, arterial stiffness, and peripheral endothelial function were evaluated at the beginning of the study and after 1 year in both groups. Our results showed that arterial stiffness improved significantly (p = 0.022) in supplemented patients. The endothelial function increased too, even if not significantly (p = 0.688), after 1 year of melatonin administration. Moreover, the supplemented group showed a significative reduction in TAC levels (p = 0.041) correlated with the improvement of arterial stiffness. These data suggest that melatonin may play an important role in reducing the serum levels of TAC and, consequently, in improving arterial stiffness.

Keywords: cardiovascular risk; essential hypertension; melatonin; oxidative stress; peripheral arterial tonometry; pulse wave velocity; systolic and diastolic blood pressure; total antioxidant capacity.

Figure 1

Schematic representation of the relationship between applanation tonometry performed by the SphygmoCor system and the TAC plasmatic values. (CRE: μM Copper Reducing Equivalents; Aix: augmentation index).

Figure 2

Schematic representation obtained from the EndoPAT analysis: comparison between the first assessment (T0) and the one-year assessment (T1). (RHI: reactive hyperaemia index; Aix: augmentation index; Aix@75: augmentation index corrected for 75 bpm; HR: heart rate).

Figure 3

Schematic representation of the study design.

Figure 4

Peripheral arterial tonometry (PAT) signals obtained using the EndoPAT-2000 device, showing traces typical of good endothelial function (a) and of endothelial dysfunction (b). Note the difference in the post-occlusive phase, with lower amplitude, similar to baseline trace, in the latter.

Figure 5

Schematic representation of SphygmoCor CvMS carotid-femoral pulse wave velocity (cf- PWV) measurement method with sequential applanation tonometry of the carotid (marked as a red square) and femoral (marked as a red arrow) sites. Pulse transit times (tt) are calculated from the electrocardiogram (ECG) R-wave to the foot of the applanated waves. Distances (d) are measured from the suprasternal notch (s) to the sites of applanation tonometry. Modified from Butlin and Qasem, 2016; © 2016 by S. Karger AG, Basel [60].

Figure 6

Schematic representation of the data obtained from applanation tonometry performed by the SphygmoCor system (Atcor Medical, Sydney, Australia).