Our airways are guarded- 24⁄7! This interesting finding has been reported in the March issue of the American Journal of Respiratory Cell and Molecular Biology in the paper titled “Volatile-Sensing Functions for Pulmonary Neuroendocrine Cells”.
According to this finding, there are olfactory receptors located in the membranes of Neuroendocrine Cells in our lungs. These lung receptors when activated, say, by acrid smoke or some pungent odor, trigger the release of airways constricting hormones by the PNECs (Pulmonary Neuroendocrine Cells). Coughing is the logical process forward- thereby guarding our insides against toxic volatile chemicals.
These cells are secretory in nature. When we inhale some toxic volatile chemical, it reaches our lungs and triggers PNECs. The olfactory receptors act as sensors. The sensation of something acrid, pungent or toxic activates PNECs, and they respond by flooding the local nerves and muscles with serotonin and neuropeptides. As a result the airways get constricted and a rapid, involuntary, physiological response of coughing is witnessed. The whole process is fast and automatic and therefore uncontrollable- we cannot suppress our coughs under these circumstances. It is a pure sense and respond phenomenon, so common in our body systems, in action.
The receptors in our nose do sense odors. They, however, send the signal to our brains where it is processed and perception of a certain smell is elicited. The nose receptors are not secretory in nature.
The finding is of high importance for patients suffering from COPD (Chronic Obstructive Pulmonary Disease)- a broad classification of diseases in which the air ways get constricted and the patients suffer from great difficulty in breathing and violent bouts of uncontrolled coughs and wheezing. It is suspected that COPD patients have hypersensitivity to volatile and air-borne irritants because of increased PNEC dependent chemo-responsiveness.
By targeting PNECs through drugs it is expected that COPD can be more effectively controlled. Blocking these odor receptors (dulling the sensors) on the Neuroendocrine Cells, over chemo-responsiveness could be decreased, and violent, uncontrolled coughs and breathing difficulties in asthmatic attacks might be better prevented without using steroids.
This promising research has been carried out at the Washington University in St. Louis under Assistant Professor of Biology, Yehuda Ben-Shahar.