Effect of pentobarbital anesthesia on rheology and transport of canine tracheal mucus.

Tracheal mucus samples were collected from six tracheostomized dogs before and after induction of pentobarbital anesthesia. The dynamic mechanical properties of the mucus were determined by the magnetic microrheometer technique. In 15 experiments, the mean value of elasticity at 1 rad/s rose from 67 dyn/cm2 before anesthesia to 212 dyn/cm2 in the period 15-90 min after induction. At the same time, mean viscosity at 1 rad/s rose from 24 to 79 P. The mucociliary transportability of some of the mucus samples was assayed by means of in vitro frog palate technique. In 10 experiments, the relative transport rate for dog tracheal mucus went from 98% of frog palate control befor anesthesia to 79% during pentobarbital anesthesia. A negative relationship between from palate transport rate and mucus elasticity was found. A negative correlation between transport and mucus viscosity at constant elasticity was also discovered. Finally, the mucus collection rate was reduced by a factor of about 8 during anesthesia, suggesting a reduction in the average depth of mucus.