Effect of radiolabeled materials on tracheal mucous clearance in beagle dogs

Studies of tracheal mucous clearance were carried out in 6 beagle dogs using a wide range of instilled activities. The dogs were anesthetized with halothane and then 2 separate 10-microliter droplets were deposited, 1 reference droplet containing 25 muCi of 67Ga on the left side of the carina and 1 containing either 3, 50, 250, 500, or 1,000 muCi 99mTc on the right side of the carina. Simultaneous measurements of the positions of the droplets were made every minute for 25 min using a gamma camera detection system. There were no differences in velocities with increasing 99mTc activity. The movements of labeled (100 muCi) and unlabeled Teflon-bismuth discs were also compared. No significant differences were detected but the labeled discs did have slightly higher velocities.