Hydrogen sulfide may act as a chemical messenger for pain sensation, in addition to its role as a blood pressure regulator, according to Johns Hopkins researchers.
A few years ago, Solomon Snyder, M.D., professor of neuroscience at the Johns Hopkins University School of Medicine, and his research team discovered that hydrogen sulfide relaxes blood vessels and thus decreases blood pressure. Researchers elsewhere had known for years that injecting hydrogen sulfide under the skin caused pain.
Snyder's colleagues hypothesized that hydrogen sulfide triggered pain sensors, known as TRP channels, on the cell. To test this idea, graduate student Paul Scherer bathed mammalian cells containing the TRPA1 channel in a dye that glows in the presence of calcium. Then, Scherer treated the cells with hydrogen sulfide and observed cells' insides lighting up, indicating the TRPA1 channels responded to the gas. Scherer wanted to know how hydrogen sulfide stimulated the channel. He hypothesized that the gas was chemically reacting with the amino acids that make up the channel.
The amino acid cysteine was a likely candidate since it contains a chemical group that is known to react with hydrogen sulfide. To test his idea, Scherer converted the cysteines in the TRPA1 channel protein to a form that isn't chemically reactive to hydrogen sulfide. Cells making this cysteine-modified TRPA1 channel bathed in the calcium dye were treated with hydrogen sulfide gas.
The cells no longer lit up, indicating the hydrogen gas no longer stimulated the TRPA1 channel when it could no longer react chemically with the channel. "If further studies confirm that hydrogen sulfide gas does cause pain sensation," says Scherer, "perhaps tinkering with hydrogen sulfide gas production could be an avenue for ameliorating chronic or acute pain."
Poster#: 784.06/NN10, Hall F-J, Wednesday, Oct. 17, 2012, 9-10 a.m. CSTAuthors: P. Scherer, R. Barrow, T. Sakamoto, A. Mustafa, B. Paul, R. Xu, S. Vandiver, M. Caterina and S. H. Snyder