Patologia Diagnóstica: Acesso Aberto

Abstrato

Blood Pressure-Lowering Effect of Daily Hydrogen Gas Inhalation in Spontaneously Hypertensive Rats

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

Objective: Hydrogen (H₂) is a unique inert gas that has versatile effects including anti-oxidative and anti- inflammatory properties, in many diseases and conditions. A recent study demonstrated that H₂ inhalation attenuates hypertension by ameliorating the dysregulation of the autonomic nervous system in a rat model of chronic kidney disease. The aim of this study was to confirm the blood pressure-lowering effect of H₂ inhalation in other models of hypertension which the pathophysiology is the overactivity of the sympathetic nerve in the brain.

Methods: We examined whether H₂ has a salutary effect on hypertension in spontaneously hypertensive rats (SHR). We subjected SHR to inhalation of either an H₂ (1.3% H₂+21% O₂+77.7% N₂) or control (21% O₂+79% N₂) gas mixture for 1 h every day for 2 weeks (N=3, each group). Blood pressure and heart rate were measured weekly for a total of 3 weeks: during 2 weeks of H₂ inhalation and then for 1 week without H₂ inhalation, using the telemetry system in freely moving rats.

Results: In SHR, daytime blood pressure and heart rate increased over the time, but daily 1-h H₂ inhalation suppressed these changes (P=0.001, P=0.03, respectively). The effect of lowering blood pressure and heart rate was associated with the suppression of sympathetic overactivity and restoration of parasympathetic underactivity (P=0.02). The therapeutic effect of H₂ on the autonomic imbalance was also observed at night, and this effect persisted even 1 week after the discontinuation of H₂ inhalation (P=0.006).