Relationship between plasma angiotensinII, leptin and arterial blood pressure

Obesity and hypertension are 2 closely associated conditions and obesity probably predisposed to hypertension. The mechanism of the association between obesity and hypertension is not clear. The aim of the present study was to clarify the relationship between blood pressure (BP), body mass index (BMI), serum angiotensinII (AGII) and serum leptin levels and to investigate the relation between serum AGII and leptin. This study also aimed to rule out if there is a difference in serum AGII and leptin levels between lean and obese hypertensive females.

We measured fasting serum AGII and leptin levels in 16 normotensive lean (LN) females, 25 obese normotensive (ON) females, 12 lean hypertensive (LH) females and 25 obese hypertensive (OH) females. All subjects had no evidence of preexisting cardiovascular disease, were non pregnant, had no previous history of ill health or smoking and were not on antihypertensive therapy. This study was performed in King Abdul-Aziz University Hospital, Jeddah, Kingdom of Saudi Arabia from January 2002 through to January 2003

In lean groups, there were a significant increase in BMI and serum AGII in hypertensive group compared to normotensive group while the serum leptin level was insignificantly higher in hypertensive group than in normotensive group. On the other hand, there was a significant increase in serum AGII, BMI and serum leptin for obese hypertensive compared to obese normotensive group. The mean arterial blood pressure (ABP) was significantly correlated to serum AGII, serum leptin and BMI in all groups. A significant correlation was found between serum AGII and serum leptin if all studied females (LN, LH, ON and OH) or obese females (ON and OH) were analyzed (P=0.000 and 0.04). However, in lean females (LN and LH) there was no relation between serum AGII and serum leptin.

When obesity is present, both serum AGII and serum leptin were strong predictor of BP, which is not the case in lean females in whom only serum AGII is a predictor of BP. Elevation of serum AGII and serum leptin levels when associated with increased BMI may contribute to the pathophysiology of obesity induced hypertension. Further study on leptin resistance in obese persons and its relation to increased ABP has to be carried out.