April 17 (HealthDay News) -- Mice can sense oxygen through their skin, says a new study that showed the skin plays a major role in sensing oxygen levels in the environment and in stimulating kidney production of the hormone erythropoietin (EPO) when oxygen levels decline.

EPO boosts production of red blood cells that carry and deliver oxygen throughout the body. If this finding is replicated in humans, it could lead to new ways to treat anemia and other diseases that affect red blood cell counts. It may also prove important for endurance athletes, who sometimes train at high altitudes or in low-oxygen tents to increase EPO and red blood cell levels, said Randall Johnson, of the University of California, San Diego.

It's long been known that amphibians can breathe in part through their skin, but the finding that skin plays a role in oxygen sensing in mammals was a surprise, Johnson said. This suggests that oxygen-sensing in skin is an ancient feature and was retained during the evolution of mammals.

"As it turns out, when we looked for the ion channels involved in this process in frog skin -- which are also present in mammalian lungs -- we found the same channels present in the skin of a mouse. No one had ever looked," Johnson said in a prepared statement.

In their tests with mice, Johnson and his colleagues showed that the underlying physiology of the oxygen sensing response in the skin of mice includes an increase of blood flow to the skin. They also found that applying nitroglycerin to the skin of the mice boosted EPO and red blood cells levels.

The study was published in the April 18 issue of Cell.

"EPO administration is a multi-billion dollar drug market for the treatment of all sorts of diseases involving low red blood cell counts," Johnson said. "The ability to manipulate red blood cell production just by changing blood flow through certain parts of the skin could be profound. We show in this study that, by just placing a little nitroglycerin patch, we were able to trigger very big increases in EPO. Whether this will turn out to be true for humans, we don't know yet."

SOURCE: Cell Press, news release, April 17, 2008