Characterization of Alveolar Epithelial Cell Injury after Exposure to Nitric Oxide and Oxygen † 1722

Abstract

Nitric oxide (NO) is currently being used for pulmonary hypertension. When NO is administered with oxygen (O2), the combination of gasses may be toxic to alveolar epithelial cells. To evaluate cellular toxicity, alveolar type-II (AT-II) cells were exposed to NO (1, 5, 10 and 20ppm) alone and in combination with O2. Cells were studied for viability and function. Media was studied for direct cellular exposure of NO and to elucidate mechanism of injury. For each concentration of NO, AT-II cells from 8 adult rats were isolated, purified, and divided into 4 treatment groups: NO+95% O2, NO+room air (RA), 95% O2, and RA. After a 4 hour gas exposure, cells were evaluated for viability by fluorescent staining and for function by radioactive glucose uptake. Media was measured for nitrite by chemiluminescence and for nitrosylated glutathione (GSNO), a peroxynitrite metabolite, by light absorbance. The table shows percent cell death±SEM for the 4 treatment groups. In the 1ppm treatment group there was no difference in the amount of cell death, while at 5ppm there was a slight increase in the amount death in the NO exposed cells. Cells exposed to 10ppm NO+O2 continued to show a slight increase in cell death compared to NO+RA, O2 and RA groups. Not only was there an increased amount of cell death in cells exposed to 20ppm NO+RA, the greatest amount of death occurred in the NO+O2 group compared to other NO exposed cells and controls. One and 5ppm NO+O2 groups showed no difference in glucose uptake. When cell death was plotted against nitrite or GSNO levels, there was direct correlation in cells exposed to NO+O2, r2=0.90 and 0.92.