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. The NO-derived compound regulates blood pressure by dilating blood vessels (SN: 3/23/96,

p. 180).

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.

“Oxygen works in concert with, and under the control of, SNOs,” Stuart Lipton of

the Burnham Institute in La Jolla notes in a Nature commentary. He adds that the new work supports a theory that hemoglobin originally evolved to carry NO, not

oxygen (SN:1/29/00, p. 79).