Assessment of endothelial function by acetylcholine iontophoresis: Impact of inter-electrode distance and electrical cutaneous resistance

Abstract

ObjectivesEndothelial function can be assessed by acetylcholine (ACh) iontophoresis with single current application. The effect of inter-electrode distance as well as electrical cutaneous resistance (ECR) on ACh dependent vasodilation has never been studied using single current application. The aims of this study are (i) to compare ACh-peak and ECR measured at different inter-electrode distances, (ii) to assess the relationship between ACh-peak and ECR, (iii) and to study the reproducibility of the ECR values. MethodsFourteen healthy subjects were included. Using laser speckle contrast imaging, ACh-iontophoreses (0.1mA, 30s) were performed on the forearm at a 7-day interval with an inter-electrode distance set at 5cm. Two other inter-electrode distances were also evaluated: 10cm and 15cm. ECR was measured during each ACh-iontophoresis as well as the ACh-peak. ResultsNo statistical difference was found between the ACh-peak values obtained at 5cm, 10cm and 15cm. ECRs were also not statistically different. An inverse relationship (r=−0.60) was found between the ACh-peak and ECR (p<0.05). The coefficient of variation of the inter-day reproducibility of the ECR values was 9.1% [6.5%–15.1%] with an intra-class-correlation coefficient of 0.93 [0.81–0.98]. ConclusionInter-electrode distance ranging from 5cm to 15cm changes neither the ACh-peak value nor the ECR value. ECR impacts ACh-peak values.