March 6, 2013
Bitter Tasting Substances Can Help With Asthma Attack
Alan McStravick for redOrbit.com — Your Universe Online
The sudden onset of an asthma attack can be a frightening event. Asthmatics often experience a severe shortness of breath combined with coughing or wheezing and a tightening sensation in their lungs and chest. If you suffer from asthma, there is a chronic state of inflammation in your lungs. When this inflammation is paired with constriction of the airwaves and muscles in the chest, it is important to seek immediate relief, either via a bronchodilator or emergency medical care.
When your body experiences one form of inflammation or another, it is typically in response to something your body regards or perceives as foreign or harmful. With sufferers of asthma and chronic obstructive pulmonary disease (COPD), the inflammation may appear for seemingly no reason and last for far too long. These unexpected occurrences can be harmful.
Additionally, airway constriction, also known as bronchoconstriction, may accompany an onset of inflammation. The combination of bronchoconstriction with an onset of inflammation can further limit your airway function making it just that much harder to breathe.
It is bronchoconstriction (and how to mitigate it) that researchers at the University of Massachusetts Medical School (UMMS) have been researching lately. And their findings may be both surprising and welcome among the asthma and COPD communities.
The new study, focusing on the effects of bitter foods on our physiology, was conducted by an interdisciplinary team of scientists from UMMS and was published this week in the open access journal PLOS Biology. The team claims their research represents an important step forward in gaining an understanding of how certain substances that are responsible for making some foods bitter in taste can also play a part in helping to reverse the contraction of airway cells. The reversal of bronchoconstriction is known as bronchodilation.
"I am excited that someday, with more research, there may be a new class of bronchodilators which are able to reverse an asthma attack quicker and with fewer side effects than is currently available to patients," said Ronghua ZhuGe, PhD, associate professor of microbiology and physiological systems and senior author of the study.
Most of us learned in our 5th grade science classes about the specific regions of our tongue that sense the five primary tastes humans can perceive. One region can interpret sweet flavors. Others on the tongue let us know when something is salty or sour or savory. And then there is the region responsible for sensing bitter flavors.
It is believed that these bitter receptors on the human tongue first evolved to act as an alert system for the body, providing a heads up to the ingestion of potentially harmful foods that may have spoiled or are toxic. While conventional wisdom has held that these receptors exist solely in certain cells present on the tongue, new information has come to light showing these cells are present in several other locations throughout the human body.
Most notably, researchers have determined the existence of bitter taste receptors on smooth muscle cells contained in the airway. When triggered by a bitter chemical, the receptor cells in the airway relax. The physiology of this reaction to the introduction of bitter chemicals was, prior to this research, unknown. ZhuGe and colleagues chose this effect as the benchmark of their study. Specifically, they wanted to understand the effect of bitter substances on the contraction of airways and in single isolated cells.
As an asthma attack commences, there is a mass opening of channels on the membrane of smooth muscle cells in the airways. Once opened, calcium floods into the cell. This rush of calcium causes the signature contraction experienced in an asthma attack. The sufferer experiences a far-limited ability to breathe. ZhuGe states the research team was able to determine that bitter substances act in shutting down the flow of calcium, allowing for bronchodilation.
Most receptors in the human body, bitter taste receptors included, cross the plasma membrane of the cell. This means the part of the receptor outside of the cell is responsible for binding (or sensing) bitter substances that come into direct contact with the outside of the cell. When a bitter substance binds to a receptor, a G-protein is released by the cell. Once released, the G-protein splits into two separate parts. The first is the G alpha subunit. The second is the G beta-gamma dimer. “It is the G beta-gamma dimer that likely acts to close the calcium channels on the plasma membrane,” stated Kevin Fogarty, director of the biomedical imaging group in the program in molecular medicine at UMMS, and a co-author of the study. “Once the channels are closed, the calcium level returns to normal and the cells relax. This ends the asthma attack.”
"With this new understanding of how bitter substances are able to relax airways, we can focus our attention on studying these receptors and on finding even more potent bitter compounds with the potential to be used therapeutically to end asthma attacks," said Dr. ZhuGe.
For the estimated 1 in 12 individuals who currently suffer from asthma and others who have been diagnosed with COPD, the results of this study must be welcome news, indeed. At the onset of an attack, if no prescribed inhaler is present, it is comforting to know relief may be in their own kitchens, in the form of a bitter leafy green or a tart melon.