Does a beta 2-stimulator really facilitate mucociliary transport in the human lungs in vivo? A study with procaterol

The purpose was to study whether procaterol, a beta 2-stimulator, facilitated mucociliary transport on the ciliated airways in the human lungs. From immediately after inhalation of [99mTc]albumin aerosol, radioactivity of the thorax was continuously measured anteriorly by a gamma camera with the examinee in the supine position; the data were sequentially stored in a computer in 10-s frame mode. Three puffs (30 micrograms) of procaterol were inhaled from a metered dose inhaler at 60 min in the same supine position, and measurement of radioactivity was continued for 30 min more. Spirometry was performed before and after the measurement of radioactivity. A group of 8 normal subjects and 34 patients with various lung diseases, including 6 with bronchial asthma in remission, were studied. In addition to observation of mucus transport on the large airways by radioaerosol inhalation lung cinescintigraphy, the time-activity curve from the right lung was evaluated and the quantitative parameters for evaluating mucociliary clearance were calculated for the right lung. Following inhalation of procaterol, there were neither significant acceleration in mucus transport on the large airways by cinescintigraphy nor significant changes in the slope of time-activity curves. Quantitative parameters did not show any significant changes either, although spirometry indicated significant bronchodilation. We conclude that three puffs of inhaled procaterol neither necessarily accelerate mucus transport nor facilitate mucociliary clearance in the human lung.