A few sprints up and down the soccer field or a hike up a mountain can make people
short of oxygen and breathe more rapidly than normal. Investigators have now found
that a form of nitric oxide (NO), not oxygen, provides the direct signal to the
brain that stimulates this panting.
Several years ago, biologists were surprised to learn that hemoglobin carries a
version of NO, as well as oxygen, around the body in red blood cells. The NO-derived compound regulates blood pressure by dilating blood vessels (SN: 3/23/96,
Now, Benjamin Gaston of the University of Virginia School of Medicine in
Charlottesville and his colleagues find that oxygen-poor blood produces NO-derived
compounds called S-nitrosothiols, or SNOs. These compounds act within the
respiratory center of a rat's brain to induce rapid breathing, the team reports in
the Sept. 13 Nature.