Related Experiment Video
Updated: Nov 17, 2025
Assessment of Human Adipose Tissue Microvascular Function Using Videomicroscopy
Published on: September 29, 2017
Hypertension preserves the magnitude of microvascular flow-mediated dilation following transient elevation in
William E Hughes1,2, Natalya Zinkevich2,3, David D Gutterman1,2,4
1Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, USA.
Insights
Transient increases in intraluminal pressure impair flow-mediated dilation (FMD) in coronary artery disease (CAD) and non-CAD arterioles. However, hypertension preserves FMD by shifting the dilation mechanism from nitric oxide (NO) to hydrogen peroxide (H2O2).
Area of Science:
- Vascular Physiology
- Cardiovascular Research
- Hypertension Studies
Background:
- Flow-mediated dilation (FMD) assesses endothelial function, crucial for cardiovascular health.
- Coronary artery disease (CAD) and hypertension are major risk factors for endothelial dysfunction.
- Understanding how pressure changes affect FMD in different patient groups is vital for cardiovascular disease management.
Purpose of the Study:
- To investigate the impact of transient increases in intraluminal pressure (IILP) on FMD in resistance arterioles.
- To compare the response of arterioles from non-CAD, CAD, and hypertensive non-CAD individuals.
- To elucidate the underlying mechanisms of FMD changes under simulated hypertensive conditions.
Main Methods:
- Resistance arterioles were isolated from human adipose and atrial tissues.
- IILP was simulated by applying 150 mmHg for 30 minutes.
- FMD and endothelial-independent dilation were measured before and after IILP exposure, with pharmacological interventions (L-NAME, peg-cat) used to probe dilation pathways.
Main Results:
- IILP significantly reduced FMD in both non-CAD and CAD arterioles.
- Arterioles from hypertensive non-CAD subjects showed no reduction in maximal FMD after IILP.
- In hypertensive non-CAD arterioles, nitric oxide (NO) mediated FMD pre-IILP, while hydrogen peroxide (H2O2) mediated it post-IILP.
Conclusions:
- Acute exposure to increased intraluminal pressure attenuates FMD in resistance arterioles from non-CAD and CAD individuals.
- Hypertension in non-CAD individuals preserves FMD magnitude following IILP due to a compensatory shift from NO to H2O2 signaling.
- These findings highlight a protective mechanism in hypertensive individuals that warrants further investigation in cardiovascular health.
Objective:
The objective of this study was to measure flow-mediated dilation (FMD) prior to and following transient increases in intraluminal pressure (IILP) in resistance arterioles isolated from subjects with and without coronary artery disease (CAD) (CAD and non-CAD) and non-CAD subjects with hypertension.
Methods:
Arterioles were isolated from discarded surgical tissues (adipose and atrial) from patients without coronary artery disease (non-CAD; ≤1 risk factor, excluding hypertension), with CAD, and non-CAD patients with hypertension (hypertension as the only risk factor). To simulate transient hypertension, increased IILP was generated (150 mmHg, 30 min) by gravity. Arterioles were constricted with endothelin-1, followed by FMD and endothelial-independent dilation prior to and following exposure to IILP.
Results:
IILP reduced FMD in non-CAD and CAD arterioles relative to pre-IILP (p <.05 at 100 cmH2 O). In contrast, arterioles from non-CAD hypertensive subjects exhibited no reduction in maximal FMD following IILP (p = .84 at 100 cmH2 O). FMD was reduced by L-NAME prior to IILP in non-CAD hypertensive patients (p < .05 at 100 cmH2 O); however, following IILP, FMD was inhibited by peg-cat (p < .05 at 100 cmH2 O), indicating a switch from NO to H2 O2 as the mechanism of dilation.
Conclusions:
Acute exposure (30 min) to IILP (150 mmHg) attenuates the magnitude of FMD in non-CAD and CAD resistance arterioles. The presence of clinically diagnosed hypertension in non-CAD resistance arterioles preserves the magnitude of FMD following IILP as a result of a compensatory switch from NO to H2 O2 as the mechanism of dilation.
More Related Videos
10:28Evaluation of Vascular Control Mechanisms Utilizing Video Microscopy of Isolated Resistance Arteries of Rats
Published on: December 5, 2017
08:42Ultrasound Assessment of Endothelial-Dependent Flow-Mediated Vasodilation of the Brachial Artery in Clinical Research
Published on: October 22, 2014
Related Concept Videos
01:18Hypertension and Regulation of Blood Pressure
01:29Hypertension II: Pathophysiology
01:28Hypertension I: Introduction
01:30Hypertension III: Clinical Manifestations and Diagnostic Studies
01:23Antihypertensive Drugs: Vasodilators
01:30Alterations in Blood Pressure
Hypertension (High blood pressure)
Hypertension occurs when blood pressure readings consistently exceed the normal range. It is diagnosed when systolic blood pressure (the top number, indicating pressure while the heart...