Circulating Angiotensin-(1-7) is Decreased in Patients with Isolated Nocturnal Hypertension

Isolated nocturnal hypertension (INHT), defined as nighttime elevated blood pressure (BP) with normal daytime BP assessed by ambulatory BP monitoring, is associated with higher cardiovascular morbidity and mortality. We hypothesized that an alteration in the circulating renin-angiotensin system (RAS) contributes to INHT development. We examined circulating levels of angiotensin (Ang) (1-7) and Ang II and ACE2 activity in 26 patients that met the INHT criteria, out of 50 that were referred for BP evaluation (62% women, 45 +/- 16 years old). Those with INHT were older, had a higher BMI, lower circulating Ang-(1-7) (P = 0.002) and Ang II levels (P = 0.02) and no change in ACE2 activity compared to those normotensives. Nighttime DBP was significantly correlated with Ang-(1-7) and Ang II levels. Logistic regression showed significant association in Ang-(1-7) and Ang II levels with INHT. Our study reveals differences in circulating RAS in individuals with INHT.