Aims: 

Hydrogen sulfide (H₂S) is a toxic gas which deserved attention as the third gaseous transmitter, a signaling molecule regulating important biological processes. The aim of this presentation is to review some of the recent data about experimental therapeutic application of H₂S on rodent as well as on large animal models of shock, sepsis and ischemia reperfusion.

Methods and results: 

Endogenous or exogenous H₂S has multiple actions, including inhibition of mitochondrial respiration, cytoprotective, vasodilatory, antioxidant and antiapoptotic effects, induction of suspended animation, and a friend or foe character as a potential inflammatory mediator (Baumgart 2009). It is applicable via inhalation or as an intravenous infusion (H₂S donor Na₂S), and has a half-life of minutes within the body. In a landmark paper (Blackstone 2005) mice exposed to H₂S inhalation reached a reversible hibernation-like state (suspended animation) with decreased energy expenditure and decreased body temperature. In anesthetized and ventilated mice inhaled H₂S offered metabolic benefit during therapeutic hypothermia in terms of improved yield of mitochondrial respiration (Baumgart 2010). During resuscitated murine sepsis the anti-inflammatory effects of inhaled H₂S has been attenuated by sepsis (Wagner 2011). In a porcine model of aortic occlusion induced ischemia/reperfusion injury intravenous H₂S reduced energy expenditure and improved noradrenaline responsiveness during reperfusion but parameters of oxidative stress or inflammation were not affected (Simon 2008). On virtually the same model but using longer ischemic period (90min vs. 30min) intravenous H₂S ameliorated organ dysfunction and glomerular histological damage and attenuated oxidative stress, NO production and systemic inflammation (Simon 2011). In hemorrhagic shock in rats H₂S has been found pro-inflammatory (Mok 2008) and in pigs in one model H₂S improved survival (Bracht 2010) while it failed to do so in another one (Drabek 2011).

Conclusion: 

Based on preclinical data H₂S has a possible therapeutic potential on organ protection (Szabó 2007) in different models, however, further investigations are warranted.