Effect of Size on the Movement of Latex Particles in the Respiratory Tract Following Local Administration

Abstract

A suspension solution of latex particles with diameters of 0.5, 1, 2, 5, and 9 μm was instilled into rat airways via an intratracheal cannula to investigate the effect of particle size on their clearance by mucociliary movement and pulmonary lymphatic drainage. Particles administered into the tracheal lumen were cleared biphasically; they were cleared rapidly in the first 2–4 h and slowly thereafter. The overall pattern of clearance was similar for all sizes of particles, but the percentage of 5– and 9–μm particles cleared in the initial rapid phase was larger than the 0.5, 1; and 2–μm particles. The particle suspension was also administered into the deep region of the lung lobes, and the translocation of the different-sized particles to the lymph nodes was determined. The translocation rates for the 0.5; 7–, and 2–μm particles were approximately 0.1–0.2% of the total lung deposition 15-days after administration and were significantly higher than those for 5– and Ppm particles.