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 (and carbon dioxide), 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 support s theory that hemoglobin originally evolved to carry NO, not oxygen (SN: 1/29/00, p. 79). J.T.
SCIENCE NEWS, VOL. 160 OCTOBER 13, 2001 PG. 232