The association of plasma resistin with dietary sodium manipulation, the renin-angiotensin-aldosterone system, and 25-hydroxyvitamin D3 in human hypertension.

OBJECTIVE: Both resistin and vitamin D have been associated with the renin-angiotensin-aldosterone system (RAAS). We investigated the association between resistin and the RAAS, and resistin and vitamin D under controlled dietary sodium conditions.
DESIGN: Retrospective cross-sectional study of subjects from the HyperPATH Consortium, who were maintained in high dietary sodium (HS) and low dietary sodium (LS) balance for 1 week each. PATIENTS: Caucasian subjects with hypertension (n=177). MEASUREMENTS: 25-Hydroxyvitamin D (25[OH]D) levels were used to assess vitamin D status. Plasma resistin and RAAS measures were evaluated on each dietary intervention.
RESULTS: Resistin levels were significantly higher in LS, where RAAS activity was high, when compared with HS balance, where RAAS activity was suppressed (6.36 vs 5.86 μg/l, P < 0.0001); however, resistin concentrations were not associated with plasma renin activity or serum aldosterone on either diet. 25(OH)D levels were positively and independently associated with resistin in both dietary conditions (HS: β=0.400, P-trend=0.027; LS: β=0.540, P-trend=0.014).
CONCLUSIONS: Dietary sodium loading reduced resistin levels, possibly by suppressing the RAAS; however, circulating RAAS components were not related to resistin concentrations within each specific dietary sodium condition. 25(OH)D was positively associated with resistin and may be involved in resistin regulation through an unknown mechanism. Further studies to understand resistin regulation in human hypertension better are warranted.