Nitric oxide (NO) and obstructive sleep apnea (OSA)

Oxidative stress and oxidant signaling in obstructive sleep apnea and associated cardiovascular diseases

Obstructive sleep apnea (OSA) has emerged as a major public health problem and increasing evidence indicates that untreated OSA can lead to the development of various cardiovascular disorders. One important mechanism by which OSA may promote cardiovascular diseases is intermittent hypoxia, in which patients are subjected to repeated episodes of brief oxygen desaturation in the blood, followed by reoxygenation. Such cycles of hypoxia/reoxygenation may result in the generation of reactive oxygen species. Some studies have demonstrated the presence of oxidative stress in OSA patients as well as in animals subjected to intermittent hypoxia. Further, modulations of nitric oxide and biothiol status might also play important roles in the pathogenesis of OSA-associated diseases. Reactive oxygen species and redox events are also involved in the regulation of signal transduction for oxygen-sensing mechanisms. This review summarizes currently available information on the evidence for and against the occurrence of oxidative stress in OSA and the role of reactive oxygen species in cardiovascular changes associated with OSA.

Erectile dysfunction in men with obstructive sleep apnea syndrome: a randomized study of the efficacy of sildenafil and continuous positive airway pressure

The aim of this study was to compare the efficacy of sildenafil and continuous positive airway pressure (CPAP) in men with erectile dysfunction (ED) and obstructive sleep apnea syndrome (OSAS). In all, 30 men were randomly treated for 12 weeks either with sildenafil 100 mg before intercourse (15 men) or CPAP during night time sleep (15 men). Under sildenafil, 97/180 (53.9%) of attempted intercourses were successful compared to 33/138 (23.9%) under CPAP. The mean IIEF (erectile function domain score) was 12.9 and 9.3 after sildenafil and CPAP treatment, respectively (P=0.007), compared to 7.9 and 7 at baseline. In all, 53.3% of patients were satisfied with sildenafil and 20% with CPAP for ED treatment (P=0.058). Although sildenafil was superior to CPAP, comorbidities and OSAS per se possibly resulted in a lower effectiveness of sildenafil compared to that in the general population of ED men. While about half of the patients were not satisfied even with the more effective treatment, we conclude that a combination of the two therapeutic tools or a different therapeutic mode should be studied further.