Impaired Endothelial Function in Healthy African-American Adolescents Compared with Caucasians

Abstract

Objective-To determine whether African-American adolescents have endothelial dysfunction compared to Caucasians and whether differences are due to differences in insulin sensitivity (S I ) or secretion.Study design-Thirty-three Caucasian (age, 13.6±2.6 yr; BMI 21.6±4.4 kg/m 2 mean ±SD) and 25 African-American (13.3±2.9 yr; 24.0±4.4 kg/m 2 ) adolescents were studied. Forearm blood flow (FBF, plethysmography) was measured before and after 5 min of arterial occlusion. S I and acute insulin response to glucose (AIRG) were measured using intravenous glucose tolerance tests and minimal modeling.Results-Baseline FBF did not differ between races. Post-occlusion FBF was lower in AfricanAmericans (17.2±1.2 versus 22.6±1.2 ml/dl/min, p=0.006). AIRG was higher in African-Americans (6050±940 versus 2410±30 μU min/ml, p=0.001). Pubertal stage had no effect. S I did not differ by race or pubertal stage. In African-Americans, percent fall in forearm vascular resistance following arterial occlusion correlated (r=0.67 p=0.001) with logAIRG. No relationships were found between percent fall in FVR and S I in either race.Conclusion-African-American adolescents have decreased endothelial function. This may be due to increased insulin secretion. Endothelial dysfunction in African-American adolescents may predispose to cardiovascular and type 2 diabetes. Keywords insulin sensitivity; insulin secretion; puberty African-American adults have increased morbidity and mortality from most of the diseases associated with the metabolic syndrome, including myocardial infarction at younger ages (1-4), stroke (5,6), hypertension (3), and type 2 diabetes in both adults and adolescents (3,7,8 Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Mechanistically, there is a close link between endothelial function and insulin sensitivity in both normotensive and hypertensive subjects (16,17). This is important because African American adolescents are more frequently insulin resistant compared to Caucasians (18,19). We therefore hypothesized that: 1) Since insulin sensitivity is decreased in African-American adolescents endothelial function would also be lower in African-American adolescents; 2) Since insulin sensitivity is lower in pubertal than in prepubertal and postpubertal subjects (20), endothelial function would also be lower in pubertal subjects than in prepubertal or postpubertal subjects, and 3) Endothelial function would be positively associated with muscle insulin sensitivity. NIH Public Access Methods SubjectsHealthy, adolescent volunteers between 8 and 18 years of age were recruited for participa...

Endothelial dysfunction and negative emotions in adolescent girls

“…Eff ect sizes were calculated in addition to p-values. Covariates were BMI and race (4,26) . The Baron and Kenny procedure (27) were planned for the mediation analysis.…”

“…For example, endothelial dysfunction, now recognized as an early stage in the pathogenesis of atherosclerosis (1) , has been reported in multiple studies of children and adolescents. These studies often use youths with adult risk factors for cardiovascular disease, e.g., diabetes or hyperlipidemia (2, 3) , but several investigations of " healthy " children or adolescents also report evidence of endothelial dysfunction (4,5) .…”

Vitamin D and Parathyroid Hormone Relationships with Urinary Nitric Oxide Metabolites and Plasma Isoprostanes in African-Americans

“…hypertension, diabetes, and heart failure) [1,8]. Even normotensive African-Americans have more impaired endothelium-dependent and endothelium-independent NO-mediated vasodilation in response to vasodilatory agonists or stimuli than whites [2,3,9,17]. Furthermore, African-Americans manifest greater intima media thickening of large resistance vessels, greater large artery stiffening, and lower arterial compliance in addition to blunted vasodilatory response to vasodilatory stimuli [2,18,19].…”

“…African-Americans, including those with normal blood pressure (BP) levels [2], have greater impairment of endothelium-derived NO function than whites [3]. In addition, African-Americans have higher levels of oxidative stress that likely contribute to the destruction of NO, thereby reducing NO bioavailability [4,5].…”

Endothelial dysfunction in African-Americans

“…Insulin causes release of endothelial nitric oxide [142] producing vasodilation [143]. Consequently in healthy African-American subjects with endothelial dysfunction have less vasodilation diminishing glucose delivery to the skeletal muscle with compensatory increased insulin secretion [144].…”