The human body naturally creates small amounts of hydrogen sulfide to help regulate functions throughout the body, from cell metabolism to blood vessel dilation. The rapidly burgeoning field of gasotransmission shows that gases are major cellular messenger molecules, with particular importance in the brain. However, unlike conventional neurotransmitters, gases can’t be stored in vesicles. Thus, gases act through very different mechanisms to rapidly facilitate cellular messaging. In the case of hydrogen sulfide, this entails the modification of target proteins by a process called chemical sulfhydration, which modulates their activity, says Solomon Snyder, D.Phil., D.Sc., M.D., professor of neuroscience at the Johns Hopkins University School of Medicine and co-corresponding author on the study.