Figure 1. Study design.

Combination of finger plethysmography (peripheral arterial tonometry, EndoPAT) with venous blood sampling from the same arm for EPR measurements of HbNO level. Changes of pulse amplitude, recorded by EndoPAT probes at baseline, during arterial occlusion (with a brachial cuff), and during reactive hyperemia (after cuff deflation) at the tip of the index finger of the ischemic arm (B) and contralateral finger of control arm (not undergoing reactive hyperemia) (A). Blood sampling for HbNO EPR assay was done at baseline (sample 1) before EndoPAT signal recording and at 1 (sample 2) and 2 (sample 3) minutes post-deflation of the cuff (post-occlusive hyperemia).