2.12. Measurement of NADPH oxidase activity by lucigenin chemiluminescence assay

NADPH oxidase activity was measured in cells grown in the serum-free medium or in the kidney cortex isolated from rats or mice as previously described [13,14]. Briefly, 20 μg of homogenates were added to the assay buffer (50 mM phosphate buffer, pH 7.0, containing 1 mM EGTA, 150 mM sucrose) with 5 μM lucigenin and 100 μM NADPH. Photon emission expressed as relative light units was measured every 30 s for 10 min in a luminometer. Superoxide production was expressed as relative light units per milligram of protein.