Response to letter from Tremblay & King: NIRS: can it measure conduit artery endothelial function?

We thank Tremblay and King for their interest in our publication (McLay et al., 2016a), which has since been followed up with studies by McLay et al. (McLay et al., 2016c, 2016b). In these studies, it is suggested that the near-infrared spectroscopy (NIRS)-derived measure of tissue oxygen saturation (StO2 ), specifically the reperfusion rate (Slope 2) following a brief period of ischemia, can be easily applied as a reliable, non-invasive measure of vascular reactivity (McLay et al., 2016a, 2016c, 2016b). As Tremblay and King mentioned, the StO2 reperfusion rate, being measured distal to the site of occlusion, provides insight on microvascular reperfusion and it was an error in our wording that wrongfully implied that the NIRS measure of Slope 2 could be used as a surrogate for conduit artery endothelial-dependent vasodilation. We appreciate this opportunity to clarify the interpretation of the present study to avoid further confusion on this topic. This article is protected by copyright. All rights reserved.