A practical look at the chemistry and biology of hydrogen sulfide.

SIGNIFICANCE: Hydrogen sulfide (H(2)S) is garnering increasing interest as a biologically relevant signaling molecule. The effects of H(2)S have now been observed in virtually every organ system and numerous physiological processes. RECENT ADVANCES: These studies have not only opened a new field of "gasotransmitter" biology, they have also led to the development of synthetic H(2)S "donating" compounds with the potential to be parlayed into a variety of therapeutic applications. CRITICAL ISSUES: Often lost in the exuberance of this new field is a critical examination or understanding of practical aspects of H(2)S chemistry and biology. This is especially notable in the areas of handling and measuring H(2)S, evaluating biosynthetic and metabolic pathways, and separating physiological from pharmacological responses. FUTURE DIRECTIONS: This brief review describes some of the pitfalls in H(2)S chemistry and biology that can lead or have already led to misleading or erroneous conclusions. The intent is to allow individuals entering or already in this burgeoning field to critically analyze the literature and to assist them in the design of future experiments.