London, Oct 26 (IANS): Skin, the largest organ, typically covering two square metres in humans, plays a surprising role in regulating blood pressure and heart rate, scientists have found in a study on mice.

The findings revealed that skin helps regulate hypertension and heart rate in response to changes in the amount of oxygen available in the environment.

High blood pressure, the risk factor for heart attack and stroke, is often caused as a result of reduced flow of blood through small blood vessels in the skin and other parts of the body to the heart.

"Given that skin is the largest organ in our body, it perhaps shouldn't be too surprising that it plays a role in regulation such a fundamental mechanism as blood pressure," said Randall Johnson, professor at the University of Cambridge.

When the heart tissue is starved of oxygen -- as can happen in areas of high altitude, or in response to pollution, smoking or obesity -- blood flow to that tissue will increase. In such situations, the increase in blood flow is controlled in part by the 'HIF' family of proteins.

For the study, published in the journal eLife, the team exposed genetically modified mice to such low-oxygen conditions.

The mice which lacked in one of two proteins in the skin (HIF-1a or HIF-2a), showed an effect on the heart rate, blood pressure, skin temperature and general levels of activity.

"These findings suggest that our skin's response to low levels of oxygen may have substantial effects on the how the heart pumps blood around the body," said Andrew Cowburn, senior research associate at the varsity.

Prior studies have revealed that blood pressure is regulated by the brain, by blood vessels, or by the kidney.

However, the study "suggests that we may need to take a look at other organs and tissues in the body and see how they, too, are implicated", in controlling blood pressure.