Comparison of circulating and local adipose tissue renin-angiotensin system in normotensive and hypertensive obese subjects.

The renin-angiotensin-aldosterone system (RAAS) plays a well-recognized role in the regulation of BP and in salt and water balance. Since hypertension affects a considerable proportion of obese patients, circulating RAAS has been studied in obese subjects with and without hypertension, albeit with conflicting results. Furthermore, attention has recently focused on the expression of the components of the Renin-angiotensin system (RAS) in some organs, including adipose tissue where it seems to be involved in the regulation of growth and differentiation. The aim of our study was to investigate circulating RAAS and adipose tissue RAS in obese patients with and without hypertension and in matched controls. PRA, and plasma and urinary aldosterone levels were measured in 35 obese, 30 hypertensive obese patients and in 20 controls. In addition, the expression of angiotensinogen (AGT) and angiotensin II type 1 receptor (AT1) genes was studied in sc adipose tissue from 8 obese, 6 hypertensive obese and 6 healthy subjects. As previously demonstrated in other studies, there were no significant differences in the levels of circulating RAAS components in the 3 groups. As regards local RAS, interestingly, we found that AT1 gene was significantly more expressed in sc adipose tissue from obese patients with hypertension than in those without hypertension and controls. By contrast, AGT levels were similar in the 3 groups. Our data do not support the hypothesis of an involvement of circulating RAAS in the development of obesity-related hypertension. On the other hand, local RAS seems to be differently regulated in sc adipose tissue from obese patients with hypertension with respect to normotensive obese patients and controls.