Involvement of the lymphatic system in salt-sensitive hypertension in humans

BACKGROUND: The mechanisms of salt sensitivity as an important intermediate phenotype of essential hypertension remain elusive. A novel theory proposes that lymphatic vessels regulate sodium and fluid homeostasis. Since vascular endothelial growth factor C (VEGF-C) plays a vital role in lymphatic capillary hyperplasia, we hypothesized that VEGF-C was involved in salt-sensitive hypertension. We therefore investigated its plasma concentration in salt-sensitive subjects. MATERIAL/METHODS: Twenty-seven subjects (BP ≤160/100 mmHg; age range 25–50 years) from a rural community of northern China were enrolled in this study. The baseline BP of volunteers was monitored for 3 days, followed by a low-salt diet for 7 days (3 g/day, NaCl) and a high-salt diet for 7 days (18 g/day, NaCl). Those who exhibited a BP increase of 10% from low-salt period to high-salt period were diagnosed as salt-sensitive subjects. The concentration of plasma VEGF-C was measured by an immunoenzyme method (ELISA). RESULT: High salt intake significantly increased the plasma VEGF-C level. It was higher in the salt-sensitive subjects (3642.2±406.1 pg/ml) than in the salt-resistant subjects (2249.8±214.6 pg/ml). The comparison of VEGF-C levels between the 2 groups had significant statistical difference (P<0.01). CONCLUSIONS: The VEGF-C level increases significantly in the salt-sensitive subjects after high salt intake. VEGF-C could be used as a biomarker of salt sensitivity.