Daily inhalation of hydrogen gas has a blood pressure-lowering effect in a rat model of hypertension

Sugai, Kazuhisa; Tamura, Tomoyoshi; Sano, Motoaki; Uemura, Shizuka; Fujisawa, Masahiko; Katsumata, Yoshinori; Endo, Jin; Yoshizawa, Joe; Homma, Koichiro; Suzuki, Masaru; Kobayashi, Eiji; Sasaki, Junichi; Hakamata, Yoji

A recent clinical study demonstrated that haemodialysis with a dialysate containing hydrogen (H(2)) improves blood pressure control in end-stage kidney disease. Herein, we examined whether H(2) has a salutary effect on hypertension in animal models. We subjected 5/6 nephrectomised rats to inhalation of either H(2) (1.3% H(2) + 21% O(2) + 77.7% N(2)) or control (21% O(2) + 79% N(2)) gas mixture for 1 h per day. H(2) significantly suppressed increases in blood pressure after 5/6 nephrectomy. The anti-hypertensive effect of H(2) was also confirmed in rats in a stable hypertensive state 3 weeks after nephrectomy. To examine the detailed effects of H(2) on hypertension, we used an implanted telemetry system to continuously monitor blood pressure. H(2) exerted an anti-hypertensive effect not only during daytime rest, but also during night-time activities. Spectral analysis of blood pressure variability revealed that H(2) improved autonomic imbalance, namely by suppressing the overly active sympathetic nervous system and augmenting parasympathetic nervous system activity; these effects co-occurred with the blood pressure-lowering effect. In conclusion, 1-h daily exposure to H(2) exerts an anti-hypertensive effect in an animal model of hypertension.