London, Nov 5 (IANS): It was always thought that the sole bodily function of olfactory receptors was to smell and they could only be found inside the nose. But a new study has found two olfactory receptors in human lung tissue.

And when the researchers from Ruhr-University Bochum in Germany activated these receptors, they found that they regulated the way in which the airways smooth muscle cells contracted.

Contraction of smooth muscle changes the size of our airways, suggesting that this research, published in the journal Frontiers in Physiology, may open new avenues for treating chronic breathing disorders -- such as asthma, emphysema and bronchitis -- that constrict and obstruct the airways.

Working with human smooth muscle cells, Benjamin Kalbe and his colleagues applied a large number of odour molecules and watched two of them activate the muscle cells.

The researchers also determined how activating the receptors with the odour molecules affected the isolated smooth muscle cells.

In their experiment, the researchers explored the impact of activating the receptors with a compound called amyl butyrate.

The study showed that the compound had different effects on the receptors.

"At the beginning of the experiment we did not expect that the olfactory receptors would have completely different effects," Kalbe said.

These results suggested that activating the receptor OR1D2 would constrict the bronchi, whereas stimulating the other receptor, OR2AG1, might help prevent airways from closing in response to pathological triggers.

To further explore the therapeutic potential of these receptors, Kalbe said his team are planning to obtain tissue from people with chronic airway diseases to compare them to healthy tissue, to observe if the receptors change in abundance or function in disease states.