Brachial artery endothelial function is stable across the morning in young men.

Saurabh S Thosar,Steven A Shea,Chad C Wiggins,Janet P Wallace

doi:10.1186/s12947-015-0036-1

Saurabh S Thosar, Steven A Shea + Show 2 more

Open Access

https://doi.org/10.1186/s12947-015-0036-1

Copy DOI

Abstract

BackgroundThe morning hours are associated with increased cardiovascular (CV) risk, and vascular endothelial function (VEF) is a strong predictor of CV disease. A diurnal rhythm in VEF has been established but the morning variation in VEF is not well-documented. Thus, we tested if VEF is impaired across the vulnerable morning period.MethodsAfter overnight fasts, eight healthy men (age 26.3 ± 3 yr) underwent assessments of VEF under standardized testing conditions every 2 h from 0700 to 1300 h on two separate days. VEF was estimated following 5 min brachial artery occlusions by hyperemic flow-mediated dilation (FMD).ResultsThere was no significant change in FMD or hyperemic shear stimulus across the 6 h vulnerable period on either day, despite changes in physical activity and meals across these periods.ConclusionIn this healthy group of young men, VEF is stable across the vulnerable morning period when typical behaviors occurred (breakfast and physical activity). Future research should focus on the roles of sleep, physical inactivity during sleep and endogenous circadian rhythm in VEF.

Highlights

The morning hours are associated with increased cardiovascular (CV) risk, and vascular endothelial function (VEF) is a strong predictor of CV disease
Baseline diameter (BD): There was no significant difference in baseline diameter (BD) between days (F1,49 < 0.19, p = 0.66) and across time (F3,49 = 1.57, p = 0.16), and no interaction between day and time (p = 0.79)
flow-mediated dilation (FMD): There was no significant difference in FMD between days (F1,45 = 3.4, p = 0.07) and across time (F3,45 = 0.19, p = 0.90), and no interaction between day and time (p = 0.85) even while controlling for BD and inter subject variability

Summary

Introduction

The morning hours are associated with increased cardiovascular (CV) risk, and vascular endothelial function (VEF) is a strong predictor of CV disease. Adverse cardiovascular (CV) events including myocardial infarction, ventricular arrhythmias and sudden cardiac death occur more frequently early in the morning, especially within 3 h of awakening [1, 2]. It can be argued that these events could be triggered by the stress of awakening from sleep or the initiation of active behaviors across the morning [3] especially in people with established CV risk. Numerous studies have documented differences in FMD at various times of the day, to our knowledge, no studies have focused on measuring endothelial function over the period of greatest CV vulnerability (0700–1300 h) while participants perform their normal routine behaviors such as physical activity and eating breakfast.

Objectives

Methods

Results

Discussion

Conclusion