Effects of hydrogen-rich water and ascorbic acid treatment on spontaneously hypertensive rats

Abstract

Hydrogen-rich water (HW) has been suggested to possess antioxidant properties of value in treatments of lifestyle diseases and for prevention of latent pathologies. To date, the potential benefits of HW against the deleterious effects of excessive salt intake and hypertension have not been investigated. Here, we first examined the effects of HW or HW supplemented with 0.1% ascorbic acid (HWA) on spontaneously hypertensive rats (SHR) that had been fed a normal diet. In comparison to control rats given distilled water (DW), we found that HW did not significantly influence systolic blood pressure (SBP) or diastolic blood pressure (DBP) in SHR; however, the increase in SBP and DBP were inhibited in the HWA group. Next, four groups of SHR were given DW, 0.1% ascorbic acid-added DW (DWA), HW, or HWA in combination with a 4% NaCl-added diet. SHR fed the 4% NaCl-added diet showed increased hypertension; HWA treatment resulted in a significant reduction in blood pressure. The HWA group tended to have lower plasma angiotensin II levels than the DW group. In addition, urinary volumes and urinary sodium levels were significantly lower in the HWA group than the DW group. Urinary isoprostane, an oxidative stress marker, was also significantly lower in the HWA group, suggesting that the inhibitory effect of HWA on blood pressure elevation was caused by a reduction in oxidative stress. These findings suggest a synergistic interaction between HW and ascorbic acid, and also suggest that HWA ingestion has potential for prevention of hypertension.

Keywords: ascorbic acid; hydrogen water; hypertension; oxidative stress; spontaneously hypertensive rats (SHR).

Fig. 1.

Preliminary experiments. (A) Dissolved hydrogen concentrations in hydrogen water (HW) after storage in either plastic bottles or aluminum pouch (Alumipouch) bottles. Three bottles were used in each group; these were closed with a lid, and kept at room temperature. (B) Water intake in rats given water supplemented with different concentrations of ascorbic acid. Ascorbic acid (0.05, 0.1, 0.2, and 0.25%) was added to distilled water (DW) and HW. Six groups of 4 animals were treated. The 200 ml aluminum pouch bottle was filled with the experimental water and the water intake of the rats was measured for 2 days. Each value represents the mean ± SEM. **P<0.01 versus DW group. (C) Dissolved hydrogen concentrations in HW and 0.1% ascorbic acid-added HW (HWA) were measured on days 0, 1, 2, 3, 4, and 5. Five bottles were used for each group. Each value represents the mean ± SEM. *P<0.05, **P<0.01.

Fig. 2.

Changes in blood pressure in spontaneously hypertensive rats (SHR) fed with a standard diet and given HW or HWA. (A) Body weight, (B) systolic blood pressure, (C) diastolic blood pressure. Three groups of 10 animals were used: control group (distilled water, DW), hydrogen water group (HW), and 0.1% ascorbic acid-added HW group (HWA). Each value represents the mean ± SEM. *P<0.05, **P<0.01 versus DW group.

Fig. 3.

Changes in (A) food and (B) water consumption in SHR. Rats were fed with the standard diet for 4 weeks before being given the 4% NaCl-added diet until the end of the experiment (12 weeks). Four experimental groups (10 animals in each) were set up: control group (distilled water, DW), 0.1% ascorbic acid-added DW group (DWA), hydrogen water group (HW), and 0.1% ascorbic acid-added HW group (HWA). Each value represents mean ± SEM.

Fig. 4.

Changes in blood pressure in SHR fed a 4% NaCl-added diet and provided with DWA, HW or HWA. (A) Body weight, (B) heart rate, (C) systolic blood pressure, (D) diastolic blood pressure. Rats were divided into 4 groups (10 animals in each): control group (distilled water, DW), 0.1% ascorbic acid-added DW group (DWA), hydrogen water group (HW), and 0.1% ascorbic acid-added HW group (HWA). Each value represents the mean ± SEM. *P<0.05, **P<0.01 HWA versus DW group. ^†P<0.05 HWA versus DWA group.

Fig. 5.

Comparison of (A) plasma angiotensin II, (B) urinary 8-OHdG, and (C) urinary isoprostane concentrations in SHR fed a 4% NaCl-added diet and given DWA, HW or HWA for 12 weeks. Rats were divided into 4 groups (10 animals in each): control group (distilled water, DW), 0.1% ascorbic acid-added DW group (DWA), hydrogen water group (HW), and 0.1% ascorbic acid-added HW group (HWA). Each value represents the mean ± SEM. *P<0.05, **P<0.01.