NO says yes to breathing fast

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.