To reach their conclusions, the researchers first looked at sensory nerves from mice, guinea pigs and humans, and showed that the receptors on the sensory nerves were activated by a number of irritants, including a key compound in cigarette smoke (acrolein) and a chemical called cinnamaldehyde. The researchers then blocked the receptors and showed that these substances no longer activated the nerves.
To establish whether activating the receptor causes coughing, the researchers looked at the effect of acrolein on guinea pigs, as they have a coughing reflex. The researchers assessed the guinea pigs' coughing after inhaling acrolein. The compound caused coughing, and the higher the concentration, the more the guinea pigs coughed. The researchers then showed that blocking the receptor using a drug significantly reduced the guinea pigs' coughing response to the compound.
Finally, researchers led by Professor Alyn Morice at the University of Hull looked at the effect of inhaling the chemical cinnamaldehyde in humans. Ten healthy, non-smoking volunteers inhaled the chemical, as well as control substances. The researchers measured their cough response on five occasions, 2-3 days apart. All of the volunteers coughed after inhaling the compound.
|Contact: Lucy Goodchild|
Imperial College London