Discovery could lead to new asthma treatments Discovery could lead to new asthma treatments Taste receptors found in lungs respond to bitterness by signaling muscles to relax. By Frank D. Roylance, Baltimore Sun October 24, 2010|5:36 p.m. Reporting from Baltimore — An unexpected discovery of taste receptors in lungs may provide asthma sufferers with more effective ways to restore free breathing during attacks, researchers at the University of Maryland School of Medicine reported Sunday. Experiments with mice and human tissues revealed that the receptors, like those found on the tongue, respond to bitter substances by signaling constricted muscles in the lungs to relax, reopening tight airways in seconds. The findings, published in the online journal Nature Medicine, could lead to the development of the first new class of asthma inhalers in 50 years, said Dr. Stephen B. Liggett, lead author of the study. Get breaking news alerts delivered to your mobile phone. Text BREAKING to 52669. Dr. Norman H. Edelman, a pulmonologist and chief medical officer at the American Lung Assn., said the discovery is not a cure. It does not address the lung inflammation asthmatics suffer or the underlying cause of the disease. But it does offer "a totally new way of opening the airways, and that's exciting," he said. For an asthmatic enduring an attack, the simple act of drawing a breath can become a prolonged struggle that Liggett likens to "breathing through a straw." Involuntary muscles in the lungs tighten, constricting the tubes, called "bronchioles," that carry oxygen to the bloodstream. At present, the long- and short-acting inhalers relied on by the 23 million asthmatics in the U.S. belong to the same family, called "beta agonists." They all work the same way, by acting on a specific receptor in the lung muscles called the "beta 2 adrenergic receptor." Liggett's team began looking for new receptors in the lungs that might provide better avenues for dilating constricted airways. They searched by grinding up lung muscle tissue, extracting its RNA molecules, and then looking for the genetic signatures of all the muscle's chemical receptors. In the data, they quickly spotted the beta 2 receptors they already knew triggered lung constriction. Among the others they noted one oddity: a bitter-taste receptor known from the tongue. It's not a taste "bud," exactly. Taste buds are clusters of receptors on the tongue that have links to the brain. The taste receptors on the lung muscles, while structurally identical, communicate only with the muscle cells. When the researchers tried bitter aerosols on constricted airways in mice or on sections of human airways freshly removed from cancer patients, they were surprised to discover the lung muscles quickly relaxed. In seconds, the airways expanded to 90% of their original volume — three times as much as they did with the beta 2 agonist inhalant. What's still unclear is why mice and humans — and perhaps many other species — would have evolved receptors in their lungs that open airways in response to bitter inhaled substances. Liggett and his team speculate in the paper that it may have arisen as a mechanism for surviving bouts of pneumonia or bronchitis. "The bacteria that cause pneumonia secrete a substance which activates these receptors," he said. The secretion is bitter, and would help to keep the airways open, allowing the person to cough up bacteria-laden fluids in the lungs, hastening recovery. frank.roylance@baltsun.com Copyright © 2010, The Baltimore Sun
Wow! That discovery should proceed quickly through testing since there really isn't a question as to the safety of inhaling bitter smells, just effectiveness. Currently I would say that this falls under the category of "can't hurt". I'll try to remember this next time I have an asthma attack. Thanks for sharing this information! I can imagine though that this will benefit adults and older childlren more than younger children due solely to the "yuck" factor- try getting a young child to willingly inhale something bitter!
