Leptin is independently associated with systolic blood pressure, pulse pressure and arterial compliance in hypertensive African women with increased adiposity: the POWIRS study

Abstract

High leptin levels are often observed in human obesity and are implicated in obesity-related hypertension. Leptin levels have been found to be higher in hypertensive obese African-American women compared to normotensive African-American women, but a direct association between leptin and blood pressure could not be obtained. Additionally, increased adiposity has been associated with higher aortic stiffness in obese African-American women, but leptin was not included in the study. The effects of leptin on cardiovascular function in African women have not yet been determined. We hypothesised that leptin is directly associated with blood pressure and decreased arterial compliance and that leptin levels are significantly higher in hypertensive overweight/obese African women compared to normotensive overweight/obese African women. A case-case control study was performed which included 98 African women. The subjects were divided into lean normotensive (lean NT), overweight/obese normotensive (OW/OB NT) and overweight/obese hypertensive (OW/OB HT). The Finometer apparatus was used to obtain a more elaborate cardiovascular profile. Serum leptin and insulin levels as well as the HOMA-IR index were determined. Various anthropometric measures were obtained. Leptin levels were elevated (Pp0.05) in the OW/OB NT and HT groups compared to the lean NT group, but were similar in the OW/OB NT and HT groups. After adjusting for obesity, insulin resistance, hyperinsulinaemia and age, a direct positive correlation was obtained between leptin and systolic blood pressure (SBP) (Pp0.05; r ¼ 0.68) in the OW/OB HT group. Additionally, leptin also correlated negatively with arterial compliance (Pp0.05; r ¼ À0.76) and positively with pulse pressure (Pp0.05; r ¼ 0.71) in the OW/OB HT group. In conclusion, even though leptin levels were the same in OW/OB HT and NT African women, leptin was directly and positively associated with SBP and pulse pressure and negatively with C W only in OW/OB HT African women, independent of obesity, insulin-resistance, hyperinsulinaemia and age.

Leptin is favourably associated with vascular function in obese Caucasians, but not in obese Africans

“…Results in sodium retention and blood pressure elevation 19 Increases plasma angiotensin II, increasing vasoconstriction and blood pressure 19 (e) Leptin has depressor effects by causing vasodilation through nitric oxide dependent and independent mechanisms [18][19][20] What this study adds (a) This is the first study to compare the associations of chronically elevated leptin levels with cardiovascular function between obese African and Caucasian women (b) Chronically elevated leptin levels are favourably associated with vascular function in obese Caucasian women, but not in obese African women African women is supported by results from a recent publication, 21 which showed leptin to be independently associated with SBP and decreased C W in obese hypertensive African women. Since the SBP and DBP of both obese African and Caucasian groups were in the normotensive range, 39 the presence of prominent positive associations between leptin and vascular function in the obese Caucasians and the lack thereof in the obese Africans, could indicate that leptin predominantly exerts pathological influences on vascular function in obese African women, as determined previously in obese hypertensive African women.…”

“…Since the SBP and DBP of both obese African and Caucasian groups were in the normotensive range, 39 the presence of prominent positive associations between leptin and vascular function in the obese Caucasians and the lack thereof in the obese Africans, could indicate that leptin predominantly exerts pathological influences on vascular function in obese African women, as determined previously in obese hypertensive African women. 21 In conclusion, even though leptin levels were similar in obese African and Caucasian women, leptin was favourably associated with vascular function in obese Caucasians, but not in obese Africans.…”

“…[18][19][20] The above-mentioned studies determined that leptin has pressor and depressor effects that would result in decreased or increased vascular function and elevated or reduced blood pressure as serum leptin levels increase with increased adiposity. Associations of chronically elevated leptin levels with cardiovascular function in obese African women are limited 21 and comparisons of leptin's associations with cardiovascular function between Africans and Caucasians absent. Recently, it was determined that leptin is independently associated with increased systolic blood pressure (SBP) and decreased C W in a group of overweight/obese hypertensive African women.…”

“…Recently, it was determined that leptin is independently associated with increased systolic blood pressure (SBP) and decreased C W in a group of overweight/obese hypertensive African women. 21 The aim of this study was to compare leptin's associations with cardiovascular function in obese African and obese Caucasian women to determine whether leptin's associations differ between these two groups.…”

Towards understanding the aetiology and pathophysiology of human hypertension: where are we now?

“…Indeed, leptin levels have been independently linked to an increased intima media thickness and sympathetic systemic activation, leading to increased vascular tone, impaired arterial distensibilty and consequently, hypertension. 21 For example, Schutte et al 21 recently investigated the effects of leptin in African subjects and found a positive association of leptin with pulse pressure and systolic blood pressure, and a negative association with arterial compliance, which was independent of the effects of obesity, hyperinsulinemia and age.…”