A baboon model for in vivo assessment of mucociliary lung clearance

Differential effects of intravenous anesthetics on ciliary motility in cultured rat tracheal epithelial cells

PURPOSE

It has been shown that airway ciliary function is impaired by several anesthetic or sedative drugs, which may predispose anesthetized or intensive care patients to respiratory complications, such as hypoxemia, atelectasis and pulmonary infection. We studied the effects of midazolam, propofol, dexmedetomidine, ketamine, fentanyl, thiopental and pentobarbital on ciliary beat frequency (CBF) in isolated and cultured rat tracheal epithelial (RTE) cells, to investigate their direct CBF action removing influences of non-epithelial cells.

METHODS

Rat tracheal epithelial cells were purely isolated from tracheas of adult male Sprague-Dawley rats. After 14 to 21 days of culture, the images of motile cilia were videotaped using a phase-contrast microscope. Baseline CBF and CBF 30 or 50 min after administration of vehicle or one of the above agents were computer-analyzed.

RESULTS

Midazolam (0.3-10 microM), propofol (1-100 microM), dexmedetomidine (1-100 nM), fentanyl (0.1-10 nM) and thiopental (30-300 microM) had no effect on CBF. Ketamine at a supraclinical dose (1000 microM) increased CBF (22 +/- 13, mean +/- standard deviation, % increase from baseline; baseline = 100%) significantly (P < 0.01). Fentanyl at a high clinical dose (100 nM) increased CBF significantly (10 +/- 9%). Pentobarbital decreased CBF dose-dependently (100 microM, -2 +/- 6%; 300 microM, -14 +/- 18%; 1000 microM, -75 +/- 5%) and reversibly (P < 0.01).

CONCLUSION

These results show that midazolam, propofol, dexmedetomidine and thiopental have no direct action on CBF in isolated RTE cells, whereas high doses of ketamine and fentanyl have direct ciliostimulatory actions and pentobarbital has a direct cilioinhibitory action.

Effect of Pseudomonas aeruginosa-derived pyocyanin and 1-hydroxyphenazine on pulmonary mucociliary clearance monitored scintigraphically in the baboon model

The effect of products of the bacterium Pseudomonas aeruginosa on mucociliary lung clearance has been monitored in vivo in the baboon model by scintigraphy. Clearance was found to be inhibited by both 1-hydroxyphenazine and pyocyanin, and a dose-effect was illustrated by the former. This confirms previous in vitro results as well as results from work on guinea-pigs, and holds good prospects for the use of the baboon model under anesthesia in such investigations.