Asymmetric dimethylarginine concentration in patients with obstructive sleep apnea

Introduction: Obstructive sleep apnea (OSA) is considered as a factor conducive to endothelial dysfunction. However, the pathogenetic mechanisms leading to this phenomenon are complex and, to-date, have not been sufficiently explained. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of endothelial nitric oxide synthase. Its elevated level is perceived as a cardiovascular risk factor. ADMA may be potentially engaged in the process of endothelial dysfunction in patients with OSA. Objective: The objective of the study was evaluation of the concentration of ADMA in blood serum in patients diagnosed with OSA. Methods: The study covered 47 patients, comprising 36 males and 11 females, aged 53.6±11.2 yr, with OSA diagnosed based on screening polysomnography (PSG). The diagnostic criteria for OSA were based on the guidelines by AASM. The control group encompassed 12 patients, including 7 males and 5 females, matched according to gender, age, and body weight. The concentration of ADMA was determined by the ELISA method, in serum samples collected during morning hours. Results: The concentration of ADMA in the study group was 0.104±0.046 mmol/l, and did not significantly differ from that observed in the control group (0.116±0.049 mmol/l; p=0.42). Also, no significant differences in the ADMA level were found according to the level of intensity of OSA. No correlations were noted between the concentration of ADMA and apnea-hypopnea index, night saturation, total antioxidant capacity, nor C-reactive protein. Conclusions: OSA is not associated with an increase in the ADMA concentration. Thus, it seems that ADMA does not play the key role in the endothelial impairment in this group of patients.