Zinc deficiency induces hypertension by paradoxically amplifying salt sensitivity under high salt intake in mice.

ABSTRACT

BACKGROUND: Hypertension is one of the major etiologies that cause chronic kidney disease (CKD) and can exacerbate kidney dysfunction. Zinc is an essential trace element playing a role in blood pressure regulation, and zinc deficiency, a common comorbidity in patients with CKD, can cause hypertension. However, the precise mechanism underlying zinc deficiency-induced hypertension is unknown. Sodium (Na+) retention due to inappropriate Na+ reabsorption in the renal tubule is the principal pathophysiology of hypertension. Therefore, this study aimed to investigate the association between zinc deficiency and salt sensitivity. METHODS: Adult mice were fed a zinc-adequate (ZnA) or zinc-deficient (ZnD) diet combined with/without high salt in drinking water (HS) for 4 weeks (n = 6 each). Changes in blood pressure, urinary sodium excretion, and the expressions of the proximal tubular Na+ transporter, Na+/H+ exchanger 3 (NHE3), which mostly contributes to filtered Na+ reabsorption and the downstream Na+-Cl- transporter (NCC) were analyzed. RESULTS: Urinary Na+ excretion significantly increased in ZnD mice, indicating that zinc deficiency causes natriuresis. NHE3 expressions were significantly suppressed, whereas NCC was upregulated in ZnD mice. Interestingly, the combination of high salt and ZnD diet (HS-ZnD) reversed the urinary Na+ loss. The NCC remained activated and NHE3 expressions paradoxically increased in HS-ZnD mice compared with those fed the combination of high salt and ZnA diet. In addition, blood pressure significantly increased only in HS-ZnD mice. CONCLUSION: The combination of zinc deficiency and high salt causes hypertension. Zinc is associated with salt-sensitivity, potentially through NHE3 and NCC regulation.