We compared the absolute values of u-AQP2 and u-ENaCβ corrected for creatinine (u-AQP2CR and u-ENaCβ-CR), fractional sodium excretion (FENa), free water clearance (CH2O), urinary excretion of prostaglandin E2 (u-PGE2), urinary excretion of cyclic-AMP (u-cAMP), and plasma concentrations of AVP, renin (PRC), angiotensin II (Ang II), Aldo, atrial natriuretic peptide (ANP), and brain natriuretic peptide (BNP) in patients with essential hypertension and normotensive controls during both HS and LS intake. The gene discussed is AQP2; the disease is essential hypertension.