OZONE-INDUCED DNA SINGLE STRAND-BREAKS IN GUINEA PIG TRACHEOBRONCHIAL EPITHELIAL CELLS IN VIVO

Abstract

Two-month-old male guinea pigs (Dunkin-Hartley strain, specific pathogen free), 4 in each group, were exposed to 0.00, 0.45, and 1.00 ppm O 3 for 72 h. The trachea with two main bronchi was removed from each animal after O 3 exposure. The trachea lavage fluid was used to measure the protein content as an index of altered tracheobronchial epithelial (TE) cell membrane permeability after O 3 exposure. The TE cells were isolated and employed for the determination of DNA single-strand breaks (SSBs) by fluorometric analysis of DNA unwinding (FADU). The statistical significance level was set atα = .05. The results show that neither the yield nor the viability of the TE cell from various O 3 treatment groups was different from that of controls. Compared to controls, the protein content was elevated significantly after 0.45 ppm O 3 exposure; however, the amount of DNA SSBs was not. The number of DNA SSBs increased significantly in the 1.00 ppm O 3 exposure group when compared to controls. Regardless of the alkali incubation time at 15°C, the double-stranded DNA left in the alkali TE cell lysate was a linear function of O 3 exposure concentrations.