In vitro estimation of tracheal mucous velocity: Comparison of a solid and a liquid marker

We compared the in vitro estimation of mucociliary transport using a solid marker (Teflon disc) to that of a liquid marker (methylene blue dye). In seven isolated canine tracheal preparations, motion of Teflon discs (2 mg/mm ²) and the advancing front of methylene blue dye droplets (0.04 mg/mm ²) were recorded simultaneously. In all comparisons, velocity of 46 pairs of Teflon discs and methylene blue dye droplets was within ± 10% of a line of identity. Mean tracheal mucous velocity by Teflons discs was 8.8 mm/min (SD 2.2), and with methylene blue dye 8.6 mm/min (SD 2.1). In all seven canine tracheas, comparison of mucous velocity was within ± 10% of a line of identity. These results indicate that the differences in such properties of a marker, i.e. liquid vs solid or their weights, per se do not affect the estimation of tracheal mucous velocity.