The Diurnal Rhythm in Natriuretic Peptide Levels

Not Applicable

Completed

Conditions: Natriuretic Peptides
Obesity
Nocturnal Blood Pressure

Registration Number: NCT03834168

Lead Sponsor: University of Alabama at Birmingham

Brief Summary: The purpose of the study to assess the diurnal rhythm in natriuretic peptide levels and its temporal relationship with nocturnal blood pressure in obese and African-American individuals as compared with lean and white individuals.

Detailed Description: Obese and African-American individuals are at greater risk for cardiovascular morbidity and mortality than lean and white individuals. One of the key reasons for this health disparity is a higher risk of hypertension among obese and African-American individuals. The reasons for why these disparities develop are not well understood.

Natriuretic peptides are hormones produced by the heart and have a wide range of favorable cardiovascular effects such as natriuresis (sodium excretion), vasodilation, and direct inhibition of the renin-angiotensin-aldosterone system. Human studies showed the existence of 24-hour (diurnal) variations in the circulating natriuretic peptide levels.

Prior work from the investigators and others demonstrated that individuals with genetically-determined lower circulating natriuretic peptides levels have higher blood pressure and greater risk of hypertension. Further, the investigators have shown that obesity and African-American race are associated with lower natriuretic peptide levels, suggesting that relatively low natriuretic peptide levels may be a biologic determinant contributing to health disparities.

Obese and African-American individuals have a greater prevalence of nocturnal hypertension \[nighttime blood pressure \>120/80 mmHg\], which is an independent risk factor for cardiovascular events. The underlying reasons for 24-hour variations in blood pressure are unknown.

The investigators hypothesize that loss of the natural 24-hour rhythm of natriuretic peptide levels plays a role in the development of nocturnal hypertension in obese and African-American individuals. The aims of this study are:

1. to examine whether there is a presence of a 24-hour rhythm in natriuretic peptide levels among normotensive obese and African-American individuals and whether there is a difference in the rhythmicity of natriuretic peptide levels between obese and lean as well as in African-Americans and whites;

2. to examine whether there is an existence of a relationship between 24-hour variability of natriuretic peptide levels and 24-hour patterns of blood pressure and whether this relationship of rhythmicity of natriuretic peptide levels and nocturnal blood pressure differed in obese and lean individuals and by race.

Recruitment & Eligibility

Status: COMPLETED

Sex: Male

Target Recruitment: 42

Inclusion Criteria

Age 18 to 40 years
Blood pressure less than 140/90
Body Mass Index between 18.5 to 25 kg/m2 (lean) or 30 to 45 kg/m2 (obese)
Self identified African-American or white individuals
Willingness to comply with the study diet
Provide informed consent

Exclusion Criteria

History of hypertension
History of cardiovascular, renal, or liver disease
Diabetes or use of glucose-lowering medications
Use of vasoactive or diuretic medications
Atrial fibrillation
Anemia (Hematocrit <41%)
Abnormal serum sodium or potassium
Abnormal liver function tests (>3x upper limit of normal)
Current smokers
Regular users of non-steroid anti-inflammatory medications

Study & Design

Study Type: INTERVENTIONAL

Study Design: SINGLE_GROUP

Primary Outcome Measures

Name	Time	Method
Plasma MRproANP	About 24 hours on the in-patient study visit day after consuming study meals for 5 days	Assess the diurnal rhythm in circulating MRproANP levels among obese individuals and compared it with lean individuals

Secondary Outcome Measures

Name	Time	Method
Acrophase Difference in Hours Between the MR-proANP and Systolic BP Rhythm	About 24 hours on the in-patient study visit day after consuming study meals for 5 days	Assess relationship between 24-hour variability of MRproANP levels and 24-hour patterns of blood pressure and whether this relationship of rhythmicity of MRproANP levels and nocturnal blood pressure differed in obese and lean individuals and by race

Trial Locations

Locations (1): University of Alabama at Birmingham
🇺🇸
Birmingham, Alabama, United States
University of Alabama at Birmingham
🇺🇸Birmingham, Alabama, United States