Indispensably evil! The role of oxygen in nitric-oxide dependent endothelial function

Background: Endothelium derived nitric oxide (NO) is crucial in preserving vascular tone. Several evidence shows that NO bioavailability and utilization is regulated by oxygen (O2) concentration. However, there are still not sufficient experimental data to show how O2 concentration affects NO-dependent endothelial function in vasculature. Aim: To investigate the role of O2 concentration on NO-dependent endothelial function in vasculature. We hypothesized that different O2 concentration would have elicited different responses during single passive limb movement (sPLM) test, which is known to be an index of NO-dependent systemic endothelial function. Methods: Endothelium-dependent dilation was measured in 7 active men (age, 34±12 years; weight, 70±8 kg, height, 173±4 cm, VO2max 55.9±10.5 ml/min/kg) by means of sPLM test performed in a normobaric-hypoxic chamber in two conditions: Normoxic (N; FiO2 ~20.9%), and Hypoxic (H; FiO2 ~16.25%). For the two conditions femoral artery diameter, as well as basal blood flow (BF), Peak BF, ΔPeak BF, area under the curve (AUC) were calculated. Results: In H, femoral artery diameter did not change (−2.2±3.7%, p=0.675), basal BF significantly increased (+24±9%, p=0.043), as well as peak BF (+32±10%, p=0.034), ΔPeak BF (+34±15%, p=0.040), and AUC (+44±16%, p=0.018). Conclusion: As hypotized, different O2 concentrations provoked different responses during the sPLM test. These results suggest an O2-dependent NO availability and utilization, which may play an essential role in endothelial function during hypoxia. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.