Washington, March 25 (IANS) Hydrogen sulphide, whose presence one associates with the smell of rotten eggs, is not only known to kill workers in sewers, but also improve chances of survival in lower doses.
Previous investigations showed that the gas lowered body temperature and metabolic rate and also improved survival of mice when traumatic injury restricted oxygen supply.
But since hypothermia itself cuts metabolic needs, it was unclear whether the reduced body temperature was responsible for the other observed effects.
The current study was designed to investigate both that question and the effects of hydrogen sulphide inhalation on the cardiovascular system.
Researchers measured factors such as heart rate, blood pressure, body temperature, respiration and physical activity in normal mice exposed to low-dose (80 parts per million PPM) hydrogen sulphide for several hours.
They analysed cardiac function with electrocardiograms and echocardiography and measured blood gas levels. While some mice were studied at room temperature, others were kept in a warm environment – about 98º F – to prevent their body temperatures from dropping.
In all the mice, metabolic measurements such as consumption of oxygen and production of carbon dioxide dropped in as little as 10 minutes after they began inhaling hydrogen sulphide, remained low as long as the gas was administered, and returned to normal within 30 minutes of the resumption of a normal air supply.
The animals’ heart rate dropped nearly 50 percent during the gas’ administration but there was no significant change in blood pressure or the strength of the heartbeat.
While respiration rate also decreased, there were no changes in blood oxygen levels, suggesting that vital organs were not at risk of oxygen starvation.
“Producing a reversible hypo-metabolic state could allow organ function to be preserved when oxygen supply is limited, such as after a traumatic injury,” said Gian Paolo Volpato of Massachusetts General Hospital and co-author of the study.
These findings have been published the April issue of Anaesthesiology.