Scientists at Washington University in St. Louis and the University of Iowa have shown that unlike the receptors in your nose, which are located in the membranes of nerve cells, the ones in the lungs are in the membranes of neuroendocrine cells.
Instead of sending nerve impulses to your brain that allow it to "perceive" the acrid smell of a burning cigarette somewhere in the vicinity, they trigger the flask-shaped neuroendocrine cells to dump hormones that make your airways constrict.
The newly discovered class of cells expressing olfactory receptors in human airways, called pulmonary neuroendocrine cells, or PNECs, were found by a team led by Yehuda Ben-Shahar and Michael J. Holtzman.
The cells might be responsible for the chemical hypersensitivity that characterizes respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and asthma.
The odor receptors on the cells might be a therapeutic target, Ben-Shahar suggested. By blocking them, it might be possible to prevent some attacks, allowing people to cut down on the use of steroids or bronchodilators.
The study is published in the American Journal of Respiratory Cell and Molecular Biology.