Dimensional responses of bronchi in apneic dogs to airway pressure, gases and drugs

¹ U.S. Army Medical Research and Nutrition Laboratory, Denver, Colorado

To quantitate in vivo the morphological changes produced in bronchial dimensions by various stimuli, 42 sets of bronchograms were made of the right lungs of 23 anesthetized mongrel dogs. The effects of gases and drugs on bronchial length and width were estimated by comparing the bronchograms made at similar airway pressures with control bronchograms without these agents. Negative pressure, acetylcholine, histamine, 5-hydroxytryptamine (serotonin) and 5% carbon dioxide narrow bronchial segments. Positive pressure, atropine and isoproterenol widen and, to a lesser degree, lengthen them. Theophylline ethylenediamine (aminophyllinè) lacks a consistent effect on dimensions. Modifications of these techniques in man might yield data of value in differentiating bronchial abnormalities in patients with normal inspiratory bronchograms.