Some aspects of the regulation of the bronchial tree in obstructive lung disease: an introduction.

Hyperreactivity of the bronchial tree is a common characteristic in chronic obstructive lung disease. The mechanism underlying this phenomenon may be a disturbed equilibrium between contracting and relaxing forces acting upon the effector organ, the bronchial smooth muscle. The most important bronchial obstructive forces result from an increased vagal activity and from mediator release from the mast cell. The adrenergic system may be considered as a counter-regulating force inducing a bronchodilatation. This system was studied by challenge tests with histamine, acetylcholine, and propranolol. Special attention will be paid to the relationship between the propranolol response and allergic characteristics in asthmatic patients.