Serum levels of nitric oxide and endothelin-1 in vasculopathy managed with hyperbaric oxygen therapy

Background: Roles of nitric oxide (NO) and endothelin-1 (ET-1) in the local regulation of blood flow under physiological conditions are important and well known, while data on their effects and interactions in conditions of hyperbaric hyperoxia is still insufficient.Methods: This was a prospective observational study which included patients who underwent HBOT in accordance with existing therapeutic protocol for PAD during time period of six months, between January and July of 2016.Clinical stage of PAD according to Fontain was taken into account, as well as risk factors, demographic, anthropometric and clinical characteristics of studied patients.Results: The study included 64 patients with a mean age (± Sd) 60.2 ± 12.7 years, of whom 28 were female.Patients' NO serum levels generally increased after HBOT (NO before HBOT 21.6 ± 9.2 vs. NO after HBOT 23.5 ± 10.6 (p=0.2)),except in patients with stadium IV of PAD who had lower serum NO levels after HBOT (NO before HBOT 23.6 ± 11.5 vs NO after HBOT 20.4 ± 7.0 (p=0.4)),although these differences were not statistically signifficant.On the contrary, in all studied patients ET-1 level increased signifficantly after HBOT (ET-1 before HBOT 4.2 ± 11.6 vs. ET-1 after 18.3 ± 21.0 (p<0.001))including patients with stadium IV of PAD.Conclusion: Treatment of PAD using HBOT leads to the predominance of vasoconstrictor effects probably caused by elevation of serum ET-1 concentrations, while other factors such as exposure time to hyperbaric conditions, activation of antioxidant molecules, and the influx of other interfering substances must be considered in interpreting the effects of NO molecules.