Enhanced Antioxidative Defense by Vitamins C and E Consumption Prevents 7-Day High-Salt Diet-Induced Microvascular Endothelial Function Impairment in Young Healthy Individuals

Figure 1. The effect of the 7-day high-salt (HS) diet without (HS group) and with vitamin C and E (HS+C+E group) supplementation on skin microvascular reactivity in young healthy individuals. (A) Post-occlusive reactive hyperemia (PORH), (B) Acetylcholine-induced dilation (AChID), and (C) Sodium nitroprusside induced dilation (SNPID). PORH measurement is expressed as the difference between percentage of flow change during reperfusion and occlusion in relation with baseline (R-O%). AChID and SNPID are expressed as flow increase following ACh or SNP administration compared to baseline flow. Data are presented as average ± SD. LS- low-salt; HS- high-salt; HS+C+E- high-salt + C vitamin + E vitamin; R-O%- change of microvascular blood flow between reperfusion and occlusion (in relation to baseline); AChID- acetylcholine induced dilation; SNPID- sodium nitroprusside induced dilation. *p < 0.05, LS diet vs. HS diet within the HS group. † p < 0.05 HS diet vs. HS+C+E diet.

Figure 2. The effect of the 7-day high-salt (HS) diet without (HS group) and with vitamin C and E (HS+C+E group) supplementation on hydrogen peroxide and peroxynitrite (DCF-DA) formation in peripheral blood leukocytes (PBL)—granulocytes, monocytes, and lymphocytes in young healthy individuals. (A) shows gating strategy for excluding doublets and defining leukocytes subpopulations based on the size (FSC) and complexity (SSC), (B) shows histograms expressing the level of oxidative stress in individual leukocyte populations, and (C) shows the comparison of the expression of oxidative stress in monocytes at study enrollment (gray), after 7 days of low-salt (blue) and after 7 days of high-salt diets (red). (D) shows median fluorescence intensity of DCF-DA FITC. (D,E) shows the median fluorescence intensity of DCF-DA FITC on PBLs in HS and HS+C+E groups. Data are presented as mean ± SD. * p < 0.05, LS diet vs. HS diet within the HS group.

Figure 3. The effect of the 7-day high-salt (HS) diet without (HS group) and with vitamin C and E (HS+C+E group) supplementation on superoxide (DHE) formation in peripheral blood leukocytes (PBL)—granulocytes, monocytes, and lymphocytes in young healthy individuals. (A) shows gating strategy for excluding doublets and defining leukocytes subpopulations based on the size (FSC) and complexity (SSC), (B) shows histograms expressing the level of oxidative stress in individual leukocyte populations, and (C) shows the comparison of the expression of oxidative stress in monocytes at study enrollment (gray), after 7 days of low-salt (blue) and after 7 days of high-salt diets (red). (D,E) shows the median fluorescence intensity of DHE FITC on peripheral blood leukocytes in HS and HS+C+E groups. Data are presented as mean ± SD.

Figure 4. Summary of the effect of the 7-day high-salt (HS) diet on parameters of oxidative stress measured in the present study in young healthy individuals. This figure summarizes the most commonly known effects of the superoxide radical (O2•), nitric oxide radical (NO•), hydroxyl radical (OH•), and peroxyl radical (ROO•) in the formation of oxidative stress (blue), nitrosative stress (green), and lipid peroxidation (orange). The effects of enzymatic (green) and non-enzymatic (blue) components of antioxidative defense are also described, as well as the spectrum of their antioxidative activity (full arrow—the reaction they catalyze, dashed line—the spectrum of antioxidative activity). Radicals, metabolites, and enzymes that were measured in the present study as markers of oxidative stress and antioxidative defense are indicated in red filled circles. Seven days of the HS diet increased oxidative stress levels, which manifested as increased lipid peroxidation (increased serum TBARS and 8-iso-PGF2ɑ) and increased intracellular H2O2 and ONOO- production in peripheral blood leukocytes (increased DCF-DA in granulocytes and monocytes), and decreased antioxidant defense which manifested as…