Rounding up the usual suspects in O2 sensing: CO, NO, and H2S!

Oxygen sensing by the carotid body is essential in vertebrates to adapt to reduced arterial oxygen tension. In this issue of Science Signaling, Yuan et al. report an intricate signaling system to transduce a physical parameter--oxygen tension--into a biological cellular signal (neural discharge) through changes in the production of carbon monoxide (CO), the second messenger cyclic guanosine monophosphate, and hydrogen sulfide (H2S).