| Updated at: 1025 PST, Wednesday, October 27, 2010|
LONDON: Sweet, sour, salty, bitter. We were all taught the four tastes detected by our tongues, and we’re getting to know a fifth, the recently recognized savory taste, or umami.
Now researchers have found bitter taste receptors in another place: the lungs. That’s certainly unexpected, and so are the implications for potentially better asthma treatments based on the discovery.
Dr. Stephen B. Liggett and his team at the University of Maryland School of Medicine stumbled onto the bitter taste receptors when studying human lung tissue. Like tastebuds on the tongue, the receptors react to bitterness, but unlike tastebuds they do not send any signals to the brain. The researchers thought the taste receptors might have evolved as a protection against toxic plants, triggering constriction and then coughing after inhaling something bitter.
But when they exposed the receptors to bitter tastes, the lungs relaxed instead of tightening. Working with mice engineered to have a human form of asthma, they found that aerosolized bitter substances, such as quinine and saccharin (for its bitter aftertaste), opened up airways much more than the asthma medication albuterol did in similar mice.
Bitter taste receptors found in the lungs caused constricted airways to relax when exposed to bitter substances, responding more powerfully than they do to asthma drugs.
The research was conducted on cells in lab dishes and on mice, so the results might differ in humans. Also, the researchers say eating bitter food would not have the same effect seen in mice that inhaled droplets of bitter substances.