IN-VITRO EXPOSURE OF RABBIT TRACHEAL EPITHELIUM TO SO2 - EFFECTS ON MORPHOLOGY AND CILIARY BEATING

The aim of this in vitro study was to characterize the direct effects of short-term exposure to low concentrations of sulfur dioxide (SO2) o n both the morphology and the physiology of rabbit tracheal primary cu ltures. Scanning electron microscopy (SEM) studies revealed that cilia ted cells exposed for 1 hr to 10 ppm or 30 ppm SO2 exhibited aggregate d cilia. Transmission electron microscopy revealed numerous swollen mi tochondria in cells exposed to 30 ppm SO2 for 1 hr. This morphological damage to cells was coupled with physiological alterations. A 25% dec rease in ciliary beat frequency (CBF) was measured in cells exposed to 30 ppm SO2. This inhibition was partially reversible within 24 hr. Th is SO2 concentration also induced a significant depletion of cellular ATP content which was completely restored after a 24-hr recovery perio d. A correlation was found between cellular ATP level depletion and CB F decrease.