CO increases oxidative stress in ECs.

<p><b>A.</b> and <b>B.</b> ECs were exposed to 25 µM TCDC or 5mM MC for 1, 3, 6 and 12 hours with or without pretreated 500U catalase for 30 min and the intracellular ROS levels were then measured. The results shown are the mean ± SEM. *<i>P</i><0.05 compared with untreated ECs. <b>C. and D.</b> ECs were subjected to similar treatments prior to the measurement of intracellular ROS levels. The folds of lucigenin-amplified chemiluminescence are shown as the mean ± SEM. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0100677#s3" target="_blank">Results</a> are presented as the mean ± SEM (n = 3). *<i>P</i><0.05 compared with untreated ECs.</p>