Sewer gas exposure sends mice into instant suspended animation

March 26th, 2008 - 4:37 pm ICT by admin  

Washington, Mar 26 (ANI): A new study at Massachusetts General Hospital has revealed that low doses of the toxic gas Hydrogen sulfide, found in sewers, can safely and reversibly depress both metabolism and aspects of cardiovascular function in mice, producing a suspended-animation-like state.

The study found that while the heart rate and metabolism decreased in mice, blood pressure and oxygen levels still maintained.

Hydrogen sulfide is the stinky gas that can kill workers who encounter it in sewers; but when administered to mice in small, controlled doses, within minutes it produces what appears to be totally reversible metabolic suppression, said Dr Warren Zapol, chief of Anesthesia and Critical Care at MGH and senior author of the Anesthesiology study.

This is as close to instant suspended animation as you can get, and the preservation of cardiac contraction, blood pressure and organ perfusion is remarkable, he added.

Prior studies have shown that exposure to low-dose of hydrogen sulfide could lower body temperature and metabolic rate and also improved survival of mice whose oxygen supply had been restricted.

The researchers exposed the mice to low-dose (80 ppm) hydrogen sulfide for several hours and measured the factors such as heart rate, blood pressure, body temperature, respiration and physical activity.

They also examined the cardiac function and measured blood gas levels.

The findings revealed that consumption of oxygen and production of carbon dioxide dropped in 10 minutes after inhaling hydrogen sulfide and remained low as long as the gas was administered. However, they returned to normal within 30 minutes of the resumption of a normal air supply.

The heart rate reduced by nearly 50 percent but there was no significant change in blood pressure or the strength of the heart beat.

While respiration rate also dropped, there were no changes in blood oxygen levels, suggesting that vital organs were not at risk of oxygen starvation.

Producing a reversible hypometabolic state could allow organ function to be preserved when oxygen supply is limited, such as after a traumatic injury, says Gian Paolo Volpato, MD, MGH Anesthesiology research fellow and lead author of the study.

We dont know yet if these results will be transferable to humans, so our next step will be to study the use of hydrogen sulfide in larger mammals, he added. (ANI)

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