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

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. This was a prospective observational study which included patients who underwent hyperbaric oxygen therapy (HBOT) in accordance with existing therapeutic protocol for peripherial arterial disease (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. The study included 64 patients with a mean age (±Sd) 60.2±12.7 years, of whom 28 were female. Patients' NO serum levels in all observed categories before and after HBOT were not signifficantly different, except for stage II PAD (NObefore HBOT 21.9±9.6 vs. NOafter HBOT 26.2±12.1 (p = 0.04)). On the contrary, in all studied patients ET-1 level increased signifficantly after HBOT (ET-1before HBOT 4.2±11.6 vs. ET-1after 18.3±21.0 (p < 0.001)). 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.