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

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.