Nitric Oxide (NO) Dependent Vasodilation of Subcutaneous Arterioles Correlates with in vivo Conduit Vessel and Digital Microcirculatory Responses to Reactive Hyperemia

Subcutaneous arterioles can be readily harvested from the gluteal fat pad and offer a method for increasing our mechanistic knowledge of exposures that affect in vivo endothelial function. However, the relationships of NO dependent vasodilation of isolated subcutaneous arterioles and brachial artery reactivity (FMD) and digital pulse amplitude tonometry (PAT) in humans remain unknown. 55 human volunteers underwent FMD measurement by vascular ultrasound, PAT, and gluteal fat pad biopsy. Subcutaneous arterioles were isolated from gluteal fat. Vasodilation to increasing doses of acetylcholine (Ach, 10 −10 to 10 −7 ) was measured by video microscopy and the area under the curve for each subject was calculated (AUC Ach ). L‐NMMA exposure verified the NO dependence of the Ach response. AUC Ach was most strongly associated with PAT (r=0.39, p=0.008). AUC Ach correlated with both FMDmm and FMD% (r=0.34 (p=0.01) and 0.29 (p=0.03), respectively). AUC Ach did not correlate with peak hyperemic shear (−0.09, p=0.52). These data suggest NO bioavailability in subcutaneous arterioles reflects NO bioavailability measured by FMD and PAT. Subcutaneous arterioles reflect in vivo measurements of endothelial function and provide a promising source of vascular tissue for mechanistic studies of systemic endothelial function in humans. Research supported by K23HL089326 and the Greater Milwaukee Foundation.