J. Endocrinol. Invest. 25: 309-314, 2002 309 ABSTRACT. 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 pro- portion of obese patients, circulating RAAS has been studied in obese subjects with and without hypertension, albeit with conflicting results. Fur- thermore, attention has recently focused on the expression of the components of the Renin-an- giotensin system (RAS) in some organs, includ- ing adipose tissue where it seems to be involved in the regulation of growth and differentiation. The aim of our study was to investigate circulat- ing RAAS and adipose tissue RAS in obese pa- tients 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 con- trols. In addition, the expression of angioten- sinogen (AGT) and angiotensin II type 1 recep- tor (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 differ- ences in the levels of circulating RAAS compo- nents in the 3 groups. As regards local RAS, in- terestingly, we found that AT1 gene was signif- icantly 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 da- ta do not support the hypothesis of an involve- ment 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 hyper- tension with respect to normotensive obese pa- tients and controls. (J. Endocrinol. Invest. 25: 309-314, 2002) © 2002, Editrice Kurtis INTRODUCTION The association between obesity and hypertension is well known, albeit the causal relationship for their coexistence is still unclear (1). The circulating renin-angiotensin-aldosterone system (RAAS) plays an important role in the regulation of BP and in salt and water balance, and plasma an- giotensinogen (p-AGT) has been shown to positive- ly correlate both with BP (2) and BMI in different hu- man populations (3-5). Because of this, several stud- ies have focused on this system in the obese, al- though results have sometimes been controversial. In the last few years, adipose tissue has been rec- ognized as a real endocrine organ expressing and secreting many factors acting with an autocrine, paracrine and endocrine function at different lev- els (6). In particular, recent studies suggest the ex- istence in adipose tissue, as in a number of other organs, of a functional local renin-angiotensin sys- tem (RAS), where it seems to be implicated in both physiology and pathophysiology (7, 8). Whereas a considerable body of data is available regarding the expression of the RAS components in human adipose tissue (9), no studies have been performed, to our knowledge, on the expression of the RAS components in the adipose tissue of obese patients with and without hypertension. Key-words: Obesity, hypertension, adipose tissue, angiotensinogen, an- giotensin II receptors. Correspondence: Dr. Emanuela Faloia, Divisione di Endocrinologia, Uni- versità di Ancona, Azienda Ospedaliera “Umberto I”, 60020 Torrette, Ancona, Italy. E-mail: e.faloia@ao-umbertoprimo.marche.it Accepted September 20, 2001. Comparison of circulating and local adipose tissue renin- angiotensin system in normotensive and hypertensive obese subjects E. Faloia*, C. Gatti*, M.A. Camilloni*, B. Mariniello*, C. Sardu*, G.G.M. Garrapa*, F. Mantero**, and G. Giacchetti* *Division of Endocrinology, Department of Internal Medicine, University of Ancona, Ancona, **Division of Endocrinology, Department of Medical Sciences, University of Padova, Padova, Italy