Endothelial function was assessed via peripheral arterial tonometry, which is a non-invasive method, using the EndoPAT 2000 device (Itamar Medical Ltd., Caesarea, Israel). Two flexible probes were placed on the index fingers of both hands along with inflatable cuffs and plethysmographic biosensors. The baseline data of the two sides were collected after resting for 30 min.[12] (link) Then, cuff occlusion in the left forearm lasted for 5 min, which resulted in transitory ischemia. All data of both fingers were recorded in the process of occlusion and post-occlusion. In the course, the parameter of RHI was calculated via an automated analysis. Thus, an RHI ≥ 1.67 indicated a normal vascular endothelial function, whereas an RHI < 1.67 represented an abnormal vascular endothelial function.[13] (link)