Effects of bacterial lipopolysaccharides (LPS) and tumour necrosis factor-alpha (TNF alpha) on rat tracheal epithelial cells in culture: morphology, proliferation and induction of nitric oxide (NO) synthase.

Rat tracheal epithelial cells were cultured and the effects of LPS and TNF alpha on cell morphology, rate of proliferation and NO synthase activity were studied. NO synthase activity was determined by measuring the accumulation of 3H-L-citrulline during incubation of confluent monolayer with 3H-L-arginine. In untreated cells no significant 3H-L-citrulline formation was detected, and bradykinin and the calcium ionophore A 23187 failed to stimulate 3H-L-citrulline formation excluding a constitutively expressed, calcium-dependent NO synthase activity. After culturing the cells for 18 h in the presence of LPS (10 micrograms/ml) and TNF alpha (500 U/ml) a marked formation of 3H-L-citrulline coul…