Cultured rat trachea as a model for the study of ciliary abundance: the effect of oxygen.

THE mucociliary apparatus is the main defense mechanism preventing respiratory infection, removing inhaled debris and pathogens from the airways. Many critical care patients suffer from ciliary loss, reduced cilia beat frequency, and mucus clearance, which may be related to the high incidence of nosocomial respiratory infections within intensive care. It is often necessary to use an increased fraction of inspired oxygen (FIO2) in patients receiving intensive therapy. High FIO2 induces cough and shortness of breath and decreases vital capacity in humans, and causes pathologic alterations within the lungs of many mammals. Several studies have reported that increased FIO2 reduces mucus flow and cilia beat frequency and can lead to ciliostasis. Although oxygen-induced injury in the lung has been morphologically characterized, effects of elevated FIO2 upon the structure of the mucociliary apparatus have previously been described only qualitatively. These studies suggest that elevated FIO2 can cause apical blebbing, increased mucus discharge, and flattening of the epithelium and ciliary denudation. Our study utilized organ culture, in which tissue organization is maintained but systemic influences are eliminated, to investigate the effect of elevated FIO2 on ciliary abundance of rat trachea, using a thorough quantitative method.