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Researchers from the Massachusetts General Hospital in Boston (USA) have announced that hydrogen sulfide (sulphide) gas, H2S, can induce a state of suspended animation in mice while maintaining normal blood pressure. It is hoped that this result eventually will help in the treatment critically-ill patients. This result was presented at the American Physiological Society conference, "Comparative Physiology 2006: Integrating Diversity," in Virginia Beach, Virginai, USA, October 2006.
Hydrogen sulfide (sulphide) gas, sometimes called sewer gas, produces a noxious odour often described as a rotten egg smell. This highly toxic gas occurs naturally in swamps, some springs, and volcanoes.
The researchers administered 80 parts per million of H2S gas to their and found that their:
- heart rate fell from 500 beats per minute to 200 beats per minute
- respiration rate decreased from 120 breaths to 25 breaths per minute
- core body temperature fell from 38° C to 30° C
- activity level fell dramatically, moving only when the researchers touched them or shook their chambers
After the mice returned to breathing normal air they quickly returned to normal. Normally, as oxygen consumption goes down and heart rate decreases, blood pressure decreases also. Since the heart rate of the mice fell by more than 50%, the researchers expected blood pressure to fall, but it didn't.
"These findings demonstrate that mice that breathe 80 parts per million of hydrogen sulfide become hypothermic and decrease their respiration rate, heart rate and cardiac output without affecting stroke volume or mean arterial pressure," the authors said. This line of research could have a variety of helpful applications, including sustaining the function of organs of critically ill people, Ichinose said. It may also be possible to use the finding for patients undergoing surgery. This would be an advance, because anesthesia usually causes blood pressure to drop.