Sewer gas can induce ‘suspended animation’ in mice, say US scientists, and may help to preserve organ function in critically ill patients.
Hydrogen sulphide, a toxic gas that smells of rotten eggs, occurs naturally in swamps, springs and volcanoes.
But in mice, it was found to slow down heart rate and breathing and decrease body temperature, while keeping a normal blood pressure.
The results were presented at the American Physiology Society conference.
In the study carried out at Massachusetts General Hospital in Boston, mice were administered the gas at a concentration of 80 parts per million – a tenth of the dose which is lethal in humans.
Core body temperature also fell from 39 to 30 degrees C.
Despite the reduction in heart rate the blood pressure of the mice did not drop, which tends to happen with other techniques such as lowering body temperature.
When the researchers repeated the experiment at a higher room temperature, the heart and respiratory rate still fell significantly.
The effects of the gas seemed to be reversible with the mice returning to normal two hours after the mice started to breathe normal air again.
Previous research had shown the ability of hydrogen sulphide to induce a state of hibernation in mice but the effects on the cardiovascular system were unknown.
Some anaesthetics and sedatives can be used to slow down metabolism in the brain but currently the only way to protect other organs is to cool the body and induce hypothermia. [More]