A multidisciplinary investigation examining the circadian mechanisms regulating cardiovascular (CV) risk, with an additional focus on obesity. Specifically, in a valid circadian protocol, the investigators aim to study resting cardiovascular risk markers and the reactivity of circadian rhythms in these risk markers to standardized stressors. It is intended to compare results in lean and obese individuals to determine if there are specific risks across the circadian cycle specific to obesity. Furthermore, using an exploratory approach, the investigators propose to explore impairment in pre/post synaptic function in the cardiac left ventricle.
Overall, these studies will help us answer whether the circadian system predispose individuals to increased CV disease risk - particularly around the vulnerable morning period, and whether these risks differ with obesity. The results will serve as a foundation for clinical trials of appropriately timed dosing of medications targeting aspects of the CV system that increase effectiveness while decreasing side effects, and may have particular relevance to management of CV risk in people with obesity.
Study Type
OBSERVATIONAL
Enrollment
17
Drugs are used for as part of physiological monitoring and not as interventions, including imaging using radiopharmaceuticals (11C-meta-hydroxyephedrine, and 11C-CGP12177).
Oregon Health & Science University
Portland, Oregon, United States
Blood Pressure (BP)
Measurements were collected up to 7 times per participant across the circadian cycle under constant conditions across 5 days. Resting BP and Exercise BP data were collected at the beginning of each of 7 wake periods in a supine position and where participants exercised at an intensity equivalent to brisk walking. Salivary melatonin was used to calculate the circadian phase marker using dim light melatonin onset (DLMO). All data were assigned a circadian phase relative to DLMO and binned into 4-hour (or 60-degree) intervals. In the statistical analysis, the weight group refers to normal or overweight, exercise condition refers to seated or exercising on the bike, and circadian phase refers to the center of the circadian bin. This is an observational study. Due to insufficient enrollment and an imbalanced group distribution, we do not have sufficient statistical power to fully interpret these data. The data are valuable as pilot data for future investigations and sample size estimation.
Time frame: 5 Days
Coronary Microvascular Blood Flux
Coronary microvascular function, measured as coronary microvascular blood flux using myocardial contrast echocardiography.
Time frame: 3 days
Flow Mediated Dilation (FMD)
FMD to measure endothelial function.
Time frame: 5 days
Heart Rate
Heart rate via 2-channel echocardiogram (ECG)
Time frame: 5 Days
Epinephrine
Venous Epinephrine to estimate sympathetic output
Time frame: 5 days
Norepinephrine
Venous Norepinephrine to estimate sympathetic output
Time frame: 5 days
Cortisol
Saliva cortisol to estimate sympathetic output
Time frame: 5 days
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