NOS3 and obstructive sleep apnea syndrome: Studies by Tanaka et al. suggest that eNOS activation is sensitive to regulation by redox status and that oxidative stress leads to decreased eNOS phosphorylation, so reducing its activity [84], while Jelic and Le Jemtel supported the latter findings when they reported decreased ratios of total phosphorylated eNOS in endothelial cells from OSA [50].