Figure 2.

Characterization of the oxidant/antioxidant system in CF bronchial cells. Cu/Zn-SOD (A), Mn-SOD (B), catalase (C), glutathione superoxydase (GPx) (D), aconitase (E), and fumarase (F) activities were measured in HBE, CFBE, and CFBE-wt cells as described in Materials and Methods. One unit of the total SOD activity was defined as the amount of enzyme that inhibits the rate of pyrogallol autoxidation by 50%. The absorbance was measured at 420 nm for 5 min. Catalase activity was determined at 240 nm by measuring the decomposition of hydrogen peroxide (H₂O₂). GPx activity in the samples was determined by monitoring the decrease in NADPH absorption at 340 nm for 3 min. Aconitase activity was measured by monitoring the formation of cis-aconitate upon addition of iso-citrate (20 mM), at 240 nm and 25 °C. Fumarase activity was determined by measuring the increase in the absorbance at 240 nm at 25 °C. Values with an asterisk are significantly different from their corresponding controls (p < 0.05). Data are expressed as mean ± SE (n = 6).