H2S boosts post-heart-attack function by helping minimize reperfusion injury -- an unwanted side effect of restoring blood flow swiftly to hearts suffering from low oxygen -- said study co-author David Kraus of the University of Alabama at Birmingham.

In testing on mice, the H2S injection led to a 72 percent reduction in the amount of severe heart-tissue death after restoring normal oxygen and blood flow to mice hearts. The 72 percent reduction compares to a much larger average amount of tissue death in untreated mice hearts after the same 30 minutes of oxygen deprivation.

Findings on the protective qualities of H2S have broad implications for improving human survival after cardiac arrest, heart transplant and trauma in general, said Kraus.

"One of the most damaging biological stresses on the heart and other organs from trauma or transplantation is the rapid change in oxygen levels," Kraus said. "First there’s a drop, which elicits a dramatic cellular adjustment to survive low oxygen, and then a rapid rise caused by resuscitation."

The findings are published in the journal Proceedings of the National Academy of Sciences.