Sulfur dioxide: a novel gaseous signal in the regulation of cardiovascular functions.

The atmospheric pollutant sulfur dioxide (SO(2)) is endogenously generated from the normal metabolism of sulfur-containing amino acids through the aspartate aminotransferase pathway. SO(2) is produced in cardiovascular tissues, and the aspartate aminotransferase mRNA is localized in endothelia and in vascular smooth muscle cells near the endothelial layer. Recent studies explored the physiological and pathophysiological effects of endogenous SO(2) on the cardiovascular system, and various potential mechanisms were found. These discoveries suggest a novel role of endogenous SO(2) in the modulation of the cardiovascular system and provide a basis for new treatments for cardiovascular diseases.