Neuromechanisms of asthma.

Autonomic nervous system abnormalities may indeed underlie bronchial hyperreactivity. Imbalances between excitatory (parasympathetic, alpha-adrenergic and noncholinergic excitatory) and inhibitory (beta-adrenergic and non-adrenergic inhibitory) nervous systems at one or more loci could lead to airway hyperreactivity. The current data, however, do not clearly identify any single abnormality in the autonomic nervous system that is ubiquitous in all asthmatic patients. Rather, it appears that bronchial hyperreactivity results from many factors and that distinct autonomic nervous system abnormalities may occur in individual subjects. Future studies of how autonomic control of airway function in asthma may be disordered should prove useful in gaining a better understanding of the pathophysiology of asthma and in designing new treatment modalities.