The Role of Oxidative Stress in the Cardiovascular Consequences of Sleep Apnea

Obstructive Sleep Apnea (OSA) is the most common sleep disorder affecting up to 9-24 percent of middle aged adults, and is becoming increasingly implicated in the pathogenesis of hypertension, and other cardiovascular disorders. Up to half of patients with OSA have hypertension, and their risk of developing hypertension increases with the increasing severity of Sleep Apnea. Patients with OSA and no hypertension have endothelial dysfunction, which is believed to be the precursor for most cardiovascular disorders.

The upper airway collapse and obstruction that occur in OSA result in a pattern of intermittent hypoxia, that has been shown to be the cause of the hypertension, and endothelial dysfunction found in patients with OSA. Intermittent hypoxia results in oxidative stress, which in turn is linked to the pathogenesis of hypertension and endothelial dysfunction.

This protocol evaluates the role of the oxidative stress in endothelial function and blood pressure in patients with OSA. This is a pilot clinical study that will compare oxidative stress parameters, and endothelial function in patients with OSA before starting treatment with continuous positive airway pressure (CPAP) and 12 weeks post being on CPAP. These patients will be compared to control patients with no history of OSA. the study does not involve assignement to different treatments. All patients will receive the indicated treatment for OSA and measurements will be collected before and 12 weeks after adequate treatment.

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Key information

Conditions

Sleep Apnea Apnea Dyssomnias Nervous System Diseases Respiration Disorders Respiratory Tract Diseases Sleep Apnea Syndromes Sleep Disorders, Intrinsic Sleep Wake Disorders

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

The Ohio State University

Columbus, Ohio, 43212, United States

About this study

Obstructive Sleep Apnea (OSA) is increasingly recognized as a cardiovascular risk factor. OSA is a cause of hypertension and has strong association with atherosclerosis, coronary heart disease, diabetes stroke , and fatal cardiovascular events. Endothelial dysfunction is a preclinical vascular abnormality that predicts subsequent development of vascular disease . Patients with OSA demonstrate endothelial dysfunction in the absence of any manifested vascular disease . The mechanism of endothelial dysfunction in OSA is largely unknown. Endothelial dysfunction in OSA is reversible with antioxidants, suggesting a role for oxidant overproduction in the decreased NO availability in OSA. This provides parallels to other cardiovascular diseases in which oxidative stress induced endothelial dysfunction is important.

Recent studies reported evidence of dysfunction or decreased expression of endothelial nitric oxide synthase (eNOS) in association with increased peroxynitrite in harvested venous endothelial cells of OSA patients. We endeavored to perform the first direct quantification of microvascular endothelial genes from OSA patients. We hypothesized that patients with OSA who are free of any cardiovascular disease will have early functional changes in the microcirculatory endothelial cells that are associated with OSA, and therefore would resolve with treatment. Given the role of oxidative stress in the vascular disease of OSA, we expected to find evidence of superoxide overproduction in the microcirculatory vessels. We expected these functional changes to be reversible with treatment of OSA.

Measurement of superoxide will be done on the subcutaneous biopsy tissue using quantitative Polymerase Chain Reaction (qPCR) and immunohistochemistry techniques and image analysis software. Measurement of endothelial function will be done using Doppler ultrasound.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Completed sleep study - Older than 18

Exclusion criteria

Hypertension
Diabetes
coronary disease
Peripheral vascular disease
High cholesterol
Smoking
Pregnancy
Use of erectile dysfunction medications or supplements

Treatment and study plan

Primary outcomes

Flow Mediated Dilation

Time frame: Baseline and 12 weeks

A non-invasive test using an ultrasound to measure baseline resting vessel diameter and vessel wall dilation in upper arm post application of an inflated blood pressure cuff for five minutes. The percentage change in vessel wall dilation due to stimulation from the resting vessel diameter will be calculated for each group of participants. The results will be compared relative to each group of participants.

Other outcomes

Peroxynitrite Deposition in the Vascular Walls

Time frame: baseline and 12 weeks

A forearm biopsy will be collected to isolate human microcirculatory endothelial cells. The stain density of peroxynitrite, an indicator of oxidative stress, in the vascular walls is compared between pre-treatment and post treatment patient tissue. Also another comparison is made between pre-treatment and control tissue. The stain density is a software-generated measurement of pixel intensity and is considered to be an arbitrary unit. Higher numbers indicate greater density

Sponsors and collaborators

Lead sponsor

Rami Khayat

Other

Registry information

Important dates

Study start: 2007
Primary completion: 2010
Study completion: 2010
First posted: Jun 19, 2008
Registry last updated: Oct 30, 2013

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Published trials that share one or more normalized conditions with this study.

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