Nose's alarm system found

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Nose's alarm system found

TheStar.com - sciencetech - Nose's alarm system found

http://www.thestar.com/sciencetech/article/309300

A study in mice suggests special cells in the tip of the nose act as air quality

control sensors that protect the body from harmful chemicals. Irritating odors

set off alarms in cells in the tip of the nose, study finds

March 04, 2008

Reuters

CHICAGO – Smells so irritating they make you cough or gag may act upon a single

type of cell in the nose that senses caustic chemicals and warns the brain of

potential danger, U.S. researchers said Tuesday.

Scientists had thought such smells acted directly on nerve endings in the nose,

but the study in mice suggests special cells in the tip of the nose act as air

quality control sensors that protect the body from harmful chemicals.

" You can imagine walking into an environment where there is a lot of irritating

dust in the area. This would give you pause, " said Finger of the

University of Colorado Denver, whose study appears in the Journal of

Neurophysiology.

Finger said these chemosensory cells are found in most aquatic vertebrates,

including sharks, bony fish and lampreys. He thinks they are part of an ancient

sensory system and they are likely present in all mammals.

" The current study is the first in mammals that has a clear idea of what these

cells are responding to, " Finger said in a telephone interview.

" Some fish use them to detect predators, " he said.

In people, the cells likely trigger a response to high concentrations of

irritating chemicals. Ammonia, paint thinner or even the spray from opening a

carbonated soda can set of the alarm.

" That is the carbon dioxide triggering that little gasping response, " Finger

said.

University of Colorado Denver researcher Diego Restrepo, who also worked on the

study, said high concentrations of irritants can even trigger a reflex that

causes you to stop breathing for a few moments.

" This is one of these really hard-wired reflexes. It gives you time to get out, "

Restrepo said in a telephone interview.

The researchers used nasal tissue from mice to measure changes in chemosensory

cells as they exposed them to low and high levels of several irritating,

volatile chemical odors.

They saw evidence that the cells not only responded to the stimuli but that they

were relaying that information to nerve fibers in the nose.

And they said it takes more than a mere whiff of an offending odor to trigger

the response. Restrepo said only potentially dangerous levels of odors can set

off the protective gagging-and-coughing response.

" There are some people who are especially sensitive to these irritants. This

could have implications for their treatment, " Restrepo said.

The study was funded by the National Institute on Deafness and Other

Communication Disorders, part of the U.S. National Institutes of Health.

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