Study on the Relationship Between Plasma Nitrite and Nitrate Level and Salt Sensitivity in Human Hypertension

Abstract

Background-High salt intake suppresses the effect of nitric oxide (NO) in the peripheral resistance vessels in animal models. We tested the hypothesis that the modulation of endogenous NO is related to salt sensitivity in human hypertension. Methods and Results-Inpatients with essential hypertension (nϭ24) were maintained on a normal-salt diet (12 g/d NaCl)for 3 days, a low-salt diet (2 g), a high-salt diet (20 to 23 g), and a low-salt diet for 7 days. Normotensive subjects (nϭ16) were maintained on the first 2 salt diets. The hypertensive patients whose average 24-hour blood pressure was increased by Ͼ5% by salt loading were assigned to group 1 (nϭ8) and the others to group 2 (nϭ16). Nitrate plus nitrite (NO x ) was measured by the Griess method, and asymmetrical dimethylarginine (ADMA) by high-performance liquid chromatography. The plasma NO x level during the normal-salt diet was lower in group 1 than in group 2 and the normotensive group. After salt loading, the plasma NO x level was decreased and reversed after the second salt restriction. Plasma ADMA level was increased after salt loading and decreased after salt restriction. The change in plasma NO x level was correlated inversely with those in blood pressure (rϭϪ0.59, Pϭ0.0007) and plasma ADMA level (rϭϪ0.64, Pϭ0.003) after salt loading and restriction. Conclusions-Modulation of NO synthesis by salt intake may be involved in a mechanism for salt sensitivity in human hypertension, presumably via the change in ADMA. (Circulation. 2000;101:856-861.)

Endothelial dysfunction in normotensive salt-sensitive subjects

“…[20][21][22] However, studies performed in humans in which Abbreviations: BMI, body mass index; BP, blood pressure; NSS, normotensive salt-sensitive subject; NSR, normotensive salt-resistant subject; UK, urine potassium excretion; Una, urine sodium excretion.…”

“…5,6 Studies in patients with essential hypertension have suggested that high salt intake and/or salt sensitivity is associated with impaired endothelial function. [7][8][9] Measurement of flow mediated dilation (FMD) in the brachial artery using ultrasound is noninvasive and is an accurate indicator of NO production. [10][11][12][13] Furthermore, FMD measurement is an accepted index of conduit artery endothelial function, which can serve as an independent predictor of cardiovascular events.…”

Relationship of urinary sodium/potassium excretion and calcium intake to blood pressure and prevalence of hypertension among older Chinese vegetarians

“…Plasma concentrations of asymmetrical dimethylarginine have been reported to be increased in patients with end stage renal disease (Kielstein et al, 2001). More importantly, they are elevated in hyperhomocysteinaemia (Stuhlinger et al, 2001) and in hypertensive patients on a high salt diet (Fujiwara et al, 2000). Therefore our older vegetarian subjects might have elevated plasma concentrations of asymmetrical dimethylarginine as they had high salt intakes as reflected by urinary sodium:creatinine ratios, and they were at risk of hyperhomocysteinemia because of vitamin B12 deficiency (Mezzano et al, 2000).…”

Long-chain polyunsaturated fatty acids interact with nitric oxide, superoxide anion, and transforming growth factor-β to prevent human essential hypertension

“…These abnormalities reverted to normalcy following salt restriction. Alterations in plasma nitrite and nitrate levels correlated inversely with blood pressure and plasma ADMA levels after salt loading and salt restriction (Fujiwara et al, 2000), suggesting that salt intake modulates NO synthesis via changes in ADMA concentrations. ADMA blocks NO synthesis, which could explain, in part, the role of salt in human hypertension.…”