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Delayed asthma symptoms explained

New research, led by scientists from Imperial College London, may have discovered a potential treatment for late onset asthma symptoms.

Scientists found that blocking sensory nerve functions stopped a 'late asthmatic response' in mice and rats. The findings were published in the journal Thorax.

Many people with asthma experience a late response three to eight hours after exposure to allergens, causing breathing difficulties that may persist for up to 24 hours. In cases of an early response, the allergen is recognised by mast cells, which release chemical signals that cause the airways to narrow.

The mechanism behind the late phase has remained unclear but, in new research on mice, scientists found evidence that the late asthmatic response occurs when the allergen triggers sensory nerves in the airways. The nerves then activate reflexes which trigger other nerves that release the neurotransmitter acetylcholine, causing the airways to narrow.

Scientists have stated that if the research findings can be replicated in humans, it would mean that anticholinergic drugs, which block acetylcholine, could be used to treat asthma patients who experience late phase responses.