Renin-angiotensin system (RAS) activation and abnormalities of ambulatory blood pressure (ABP) are present in obesity, but relationships between components of the RAS and ABP have not been defined in the young. Anthropometric measurements and 24-h ABP were obtained on 30 obese adolescents with and without type 2 diabetes mellitus. Plasma renin activity (PRA), aldosterone, and other cardiovascular risk factors were measured. Median PRA levels were 2.5 [interquartile range (IQR), 1.7-4.1] ng/mL/h and were higher in the diabetic subjects compared with the nondiabetics. Females had significantly higher PRA than males 3.2 (IQR, 2-4.8) versus 1.8 (IQR, 1.1-2.9) ng/mL/h (p ϭ 0.04) and were more obese. BMI Z score and PRA were significantly correlated (rho ϭ 0.46, p Ͻ 0.001). PRA inversely correlated with 24-h systolic ABP (rho ϭ Ϫ0.46, p ϭ 0.02) and strongly with 24-h pulse pressure (rho ϭ Ϫ0.61, p ϭ 0.001). Aldosterone levels were also correlated with 24-h pulse pressure (rho ϭ Ϫ0.46, p ϭ 0.02). In multivariate models, lower PRA was independently associated with 24-h systolic blood pressure. In this study, PRA was positively correlated with BMI, but the relationships between components of the RAS and ABP were inverse. Further studies are needed to define the pathophysiologic relationship between RAS components and blood pressure regulation in obese youth. T he renin-angiotensin system (RAS) plays a central role in blood pressure (BP) regulation and fluid-electrolyte homeostasis, and its dysregulation contributes to the development of hypertension (1). Activation of the RAS in adipose tissue may represent an important link between obesity and hypertension. Studies have demonstrated that rat and human adipose tissue possess all of the components necessary for production of angiotensin II (Ang II), including angiotensinogen (2), renin-like activity (3), Ang-converting enzyme, and Ang type 1 receptor (4,5). Adipose-derived angiotensinogen is also released into the circulation where it serves as substrate for conversion to bioactive Ang II, contributes to plasma Ang II levels, and increases BP (6).Other metabolically active products of adipose tissue include adipokines. We have previously shown that adiponectin (an anti-inflammatory, anti-atherosclerotic adipokine) levels are inversely related to ambulatory blood pressure (ABP) (7), which is itself abnormal in obesity.Whether components of the RAS have similar relationships to ABP in obese youth is unknown. Our objective in this study was to examine the relationships between 24-h BP measurements and plasma renin activity (PRA) and aldosterone levels in obese adolescents.
MATERIALS AND METHODSSetting and study design. Patients who fulfilled the following criteria were recruited from the Pediatric Diabetes and Pediatric Nephrology Clinics at the Children's Hospital at Montefiore in the Bronx, NY: age 10 to 21 y, obesity defined as BMI Ͼ95th percentile for age and gender (8), a diagnosis within the past 3 y of type 2 diabetes mellitus (T2DM) according to the standar...