Respiratory cells rely on taste buds to detect poisons

July 25th, 2009 - 5:47 pm ICT by IANS  

Washington, July 25 (IANS) An Indian American researcher has found that the mechanism which helps detect bad tasting and potentially poisonous foods also protects lungs from harmful substances.
Alok Shah, study co-author and doctoral researcher from the Carver College of Medicine, University of Iowa (U-I), along with other scientists found why injured lungs are susceptible to further damage — in them, the mechanism is damaged.

The study shows that receptors for bitter compounds that are found in our taste buds are also found in hair-like protrusions on airway cells in the lungs.

Besides, the scientists showed that unlike taste cells on the tongue, these airway cells do not need help from the nervous system to translate detection of bitter taste into an action that expels the harmful substance.

The hair-like protrusions, called motile cilia, were already known to beat in a wave-like motion to sweep away mucus, bacteria and other foreign particles from the lungs.

The study shows that motile cilia on airway cells not only have this “clearing” function, but also use the receptors to play a sensory role.

The researchers also found that when the receptors detect bitter compounds, the cilia beat faster, suggesting that the sensing and the motion capabilities of these cellular structures are linked.

“On the tongue, bitter substances trigger taste cells to stimulate neurons, which then evoke a response — the perception of a bitter taste. In contrast, the airway cells appear to use a different mechanism that does not require nerves,” Shah said.

“In the airways, bitter substances both activate the receptors and elicit a response — the increased beating of the cilia — designed to eliminate the offending material.”

Shah’s co-author Yehuda Ben-Shahar said: “These findings suggest that we have evolved sophisticated mechanisms to guard ourselves from harmful environmental stimuli.

“Our work also suggests that losing cilia in the lungs, due to smoking or disease, would result in a reduced general ability to detect harmful inhaled chemicals, increasing the likelihood of further damaging an injured lung.”

These findings were published online in Science Express.

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