• Afflicts 8 million Americans and growing numbers worldwide.
• Causes serious limitations to the activity of many children.

PROGRESS IN MEDICAL RESEARCH

Asthma is a disease of the lung in which the air passages become blocked, making breathing very difficult. During an asthma attack, one feels as if they have a weight on their chest and are suffocating. Frequently, repeated coughing is experienced. Asthma often begins in childhood and the affected child has difficulty participating in sports or in certain outdoor activities. Older asthmatics may find that the environment in their workplace or home provokes their symptoms. In some individuals asthma is caused by an allergic response to pollens, animal danders, or other inhaled materials. In many individuals, however, the air passages contract in response to a variety of non-specific stimuli such as cold air and dusts. Occasionally asthma can be fatal.

What has animal research shown about asthma?

The airway obstruction characteristic of asthma is caused by the contraction of muscle surrounding the air passages, excessive secretion of mucus, and swelling of the tissues around the air passages. Animal experiments have shown that the interaction of a variety of nerves release chemicals that contract or relax the airway muscle. By understanding the function of these nerves and chemicals, investigators are able to design drugs that reverse or prevent muscle contraction and can therefore be used to treat asthma. Study of animal diseases that mimic asthma have shown that during the inflammation of the airways that accompanies asthma many cells enter the lung from the blood. Theses cells release chemicals that interact with the nerves, muscles, and mucus-secreting cells to produce the airway obstruction.

Is animal research on asthma still necessary?

One of the characteristics of asthma that is least understood is the excessive contraction of the airway muscle in response to minor stimuli. An understanding of this problem is being gained by the study of animals with asthma-like diseases. Dogs with a spontaneously occurring asthma-like disease, sheep with an allergy to parasites, horses that develop airway obstruction in response to the dusts in hay, and a variety of smaller mammals are all contributing to the understanding of diseases of the air passages such as asthma. They are revealing how the different factors in inflammation interact with nerves to cause the difficult breathing encountered by asthmatics. In addition, these mammals are providing vital knowledge about animal lung diseases.

What's ahead for sufferers of asthma?

Asthmatics rely on drugs to prevent or reverse their disease. Many of these drugs have potent side effects on the heart and other organs. Animal models and animal research are essential to sort out the interactions of all the factors involved in asthma. When these are better understood, new medications will become available with fewer side effects. These medications will restore a normal life to thousands of people whose activity is limited by their disease, and will also contribute to the relief of suffering in animals with asthma-like diseases.