Effect of ambient temperature and vapor pressure on cilia-mucus clearance rate.

Abstract

The clearance rate of Na-I131 droplets, injected low in the trachea, was measured in the upper trachea of intact anesthetized chicks by 2 detectors placed in series over the neck. Body temperature was held constant while the head was exposed to various test ambient temperatures (Ta) (40-95 F) and vapor pressures (VP) (3-39 mm Hg) following 2 days pretest exposure to the same or different Ta and VP. The clearance rate ranged from 7.4 to 17.9 mm/min. and varied directly with the test Ta and inversely with the pretest Ta and VP. Thus, it was fastest when chicks were moved from cold pretest to hot test Ta, and vice versa. The effect of test Ta on clearance was due to accompanying changes in intra-tracheal temperature. The effect of pretest Ta was not due to changes in rectal or tracheal temperatures, metabolic rate, or water content of the mucosa. The respiratory rate recorded during the test was slowest after hot pretest exposures at all test Ta and fastest with cold pretest followed by hot test Ta. Water withdrawal for 72 hr. led to a decrease in both clearance and respiratory rates.