Hydrogen Sulfide Helps Control Blood Pressure

A new study reveals that the unpleasant aroma of hydrogen sulfide (H2S) as it is expelled by bacteria living in the colon helps control blood pressure in mice.

Researchers at Johns Hopkins University (Baltimore, MD, USA) and the University of Saskatchewan (Saskatoon, Canada) compared normal mice to mice that were missing a gene for an enzyme known as cystathionine gamma-lyase (CSE)—an enzyme physiologically activated by calcium-calmodulin, which is a mechanism for H2S formation in response to vascular activation. The researchers then measured hydrogen sulfide levels taken from tissues of the altered, CSE-deficient mice, and found that the gas was depleted in their cardiovascular systems. By contrast, the normal mice had higher levels of the gas, thereby showing that hydrogen sulfide is naturally made by mammalian tissues using CSE. At the next step, the mice were subjected to higher blood pressures (comparable to serious hypertension in humans) to see how they responded to methacholine, a chemical that relaxes normal blood vessels. The blood vessels of the CSE-lacking mice hardly relaxed, thus indicating that hydrogen sulfide is an important contender for regulating blood pressure. The study was published in the October 24, 2008, issue of the journal Science.

"Now that we know hydrogen sulfide's role in regulating blood pressure, it may be possible to design drug therapies that enhance its formation as an alternative to the current methods of treatment for hypertension,” said coauthor Solomon Snyder, M.D., a neuroscientist at JHU.

Hydrogen sulfide, a colorless, toxic, and flammable gas, is now recognized as a vasodilator and a potential cardioprotective agent. It is also the most recently discovered member of the family of gasotransmitters, small molecules inside the human, and other mammals with important physiological functions. Since gasotransmitters are common all over the evolutionary tree, these findings are thought to have broad applications to several human diseases, such as diabetes and neurodegenerative disorders.

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Johns Hopkins University
University of Saskatchewan