[Bronchial hyperreactivity. I. General concepts].

Bronchial hyperreactivity is a condition in which the airways show a much greater bronchoconstrictor response to provocative stimuli than normal. Non-specific bronchial hyperreactivity is a feature of asthmatic patients both allergic and non-allergic. It is proposed that bronchial hyperreactivity is due to the fact that the airways are narrower. In addition changes in the mass of muscle, and changes in the contractility of the muscle may contribute to bronchial hyperreactivity. Moreover bronchial hyperreactivity could be due to increased alpha-adrenergic or parasympathetic activity or to decreased beta-adrenergic or non adrenergic inhibitory activity. Bronchial hyperreactivity can be induced by factors such as infection, inflammation or exposure to allergens.