In vivo and ex vivo vascular function assessments in humans: Are they related?

Both in vivo and ex vivo vascular function assessments are commonly used approaches to better understand and examine vascular health. However, the degree to which such in vivo and ex vivo assessments relate to and, therefore, complement one another, especially in humans, is not well documented. Thus, the aim of the present study was to test the hypothesis that in vivo and ex vivo assessments of endothelial-dependent vasodilation would be strongly related to each other. Both in vivo (passive leg movement (PLM), brachial artery flow-mediated dilation (FMD), and reactive hyperemia to cuff-occlusion (RH)) and ex vivo (flow- and Acetylcholine (ACh)-induced vasodilation of branched sections of the deep inferior epigastric artery) were performed on a group of women (age: 49 ± 7 years; BMI: 28.7 ± 4.8 kg/m 2 ) who underwent a deep inferior epigastric perforator (DIEP) procedure. There were positive, linear correlations between ACh-induced dilation and PLM-induced peak blood flow (r=0.81, p=0.188), PLM-induced total blood flow (r=0.82, p=0.176), FMD %dilation (r=0.99, p<0.01), FMD %dilation/shear (r=0.99, p=<0.01) and RH (r=0.21, p=0.797). Interestingly, there were no such relationships with ex vivo flow-induced vasodilation. Therefore, although this study provides evidence of strong relationships between vascular function assessed ex vivo and in vivo in humans, the current findings suggest that these relationships may be highly dependent upon the ex vivo methodology employed. This work was supported in part by Clinical Science Research and Development Career Development Award (IK2CX002114). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.