Abstract
Background: Repeated application of whole-body periodic acceleration (WBPA) upregulates endothelial nitric oxide synthase and improves brachial artery endothelial function (BAEF) as assessed by measurement of flow-mediated vasodilatation (FMD). However, the acute effect of a single application of WBPA on BAEF has not been fully characterized. In addition, although a novel semi-automatic vessel chasing system (UNEXEF18G) has now been developed in Japan, the direct comparison of UNEXEF18G with a conventional method for FMD measures has not been conducted even if UNEXEF18G has already been utilized in a relatively large scale study. Methods: We have developed a novel semi-automatic vessel chasing system (UNEXEF18G) that can measure FMD on-line, identify time to peak vasodilatation (TPV), and determine the area under the vasodilatation curve (AUC). Thus, 45 min of WBPA was applied in 20 healthy volunteers (age, $34{\pm}13$ years), and BAEF was measured by UNEXEF18G before and after WBPA. Also, UNEXEF18G measured FMD was compared with those of a conventional FMD measurement method at rest in order to validate a novel UNEXEF18G measured FMD. Results: Single WBPA resulted in a significant increase in FMD (from $6.4{\pm}3.4$ to $10.7{\pm}4.3%$, p < 0.01), a significant decrease in TPV and a significant increase in AUC. In the validation study for UNEXEF18G, Bland and Altman analysis showed that UNEXEF18G measured FMD was almost identical to those of the conventional method at rest. Conclusion: These data suggest the usefulness of a new UNEXEF18G and that single application of WBPA results in acute improvement in BAEF in humans.