Airway Reactivity

We scanned humans via electron beam X-ray CT (EBCT:Imatron) to test the hypothesis that central to peripheral differences in airway response to beta agonist will be consistent with reported airway beta receptor distribution. Baselines were obtained for six subjects and spirometry was performed after 15 minutes of inhalation of albuterol. Within 3 days, subjects returned for an EBCT study. Using a custom designed lung volume controller, each 20 slice scan was done in a single breath hold at 65% vital capacity. Twenty 3mm contiguous sections centered on the carina were acquired with 100 msec/slice scan aperture gated to the QRS complex of the ECG. EBCT was repeated 20 minutes after inhalation of albuterol. Pre and post-beta agonist cross sectional diameters of those bronchi scanned perpendicular to their local long axis were objectively quantitated using the UNIX based VIDA software package. Below are mean values for airway diameters +/- SEM from 20 airways from the current beta agonist study.

There was an inverse correlation between degree of airway diameter change and size of airway. Thus using EBCT, we confirmed that bronchodilation induced by beta agonist correlates to beto receptor distribution mapped in vitro previously by radio ligand binding assays.

For more information see:

Ct Scanning Confirms Beta Receptor Distribution is Greater for Smaller vs. Larger Airways

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Eric A. Hoffman, Ph.D.