Suspended animation-like state protects mice from lethal hypoxia

Joseph Priestley observed the high burn rate of candles in pure oxygen and wondered if people would live out too fast if we were in the same environment. We hypothesize that sulfide, a natural reducer of oxygen that is made in many cell types, acts as a buffer to prevent unrestricted oxygen consumption. To test this, we administered sulfide in the form of hydrogen sulfide (H(2)S) to mice (Mus musculus). As we have previously shown, H(2)S decreases the metabolic rate of mice by approximately 90% and induces a suspended animation-like state. Mice cannot survive for longer than 20 min when exposed to 5% oxygen. However, if mice are first put into a suspended animation-like state by a 20-min pretreatment with H(2)S and then are exposed to low oxygen, they can survive for more than 6.5 h in 5% oxygen with no apparent detrimental effects. In addition, if mice are exposed to a 20-min pretreatment with H(2)S followed by 1 h at 5% oxygen, they can then survive for several hours at oxygen tensions as low as 3%. We hypothesize that prior exposure to H(2)S reduces oxygen demand, therefore making it possible for the mice to survive with low oxygen supply. These results suggest that H(2)S may be useful to prevent damage associated with hypoxia.