Search

The aim of the present study was to investigate the impact of acute hyperglycaemia on endothelial function in both normal-weight and overweight children. A total of 16 overweight [BMI (body mass index) ≥85th percentile] and 15 normal-weight (BMI <85th percentile) children were evaluated for FMD (flow-mediated dilation) at baseline and 30, 60 and 120 min after glucose ingestion. At 15 min following the measurement of the final FMD, 0.3 mg of sublingual nitroglycerine was administered and the brachial artery was imaged in order to assess endothelium-independent dilation. By design, the overweight children were significantly heavier (63.2±4.6 compared with 41.3±2.5 kg; P=0.0003) and had a greater percentage body fat (43.9±1.8 compared with 23.8±2.05%; P<0.0001) than the normal-weight children. The area under the curve in response to glucose administration was significantly (P<0.0001) greater in the overweight group for both glucose and insulin. The FMD area under the curve was not significantly different at baseline or between time points after glucose ingestion, nor was there a difference in response between the two groups. Endothelium-independent dilation in the normal-weight group was significantly greater compared with the overweight group (26.7±1.6 compared with 20.2±2.0% respectively; P=0.019). In conclusion, these results suggest that acute elevation of glucose and insulin in overweight and normal-weight children are not associated with impairment in endothelial function. [ABSTRACT FROM AUTHOR]

Objective: To examine the association of age, sex, and obesity status on endothelial-independent dilation (EID) among children and adolescents. Study design: This study examined 264 children (143 males) between 8 to 18 years old (mean  ±  SD: age  =  14.3  ±  2.7 years). Endothelial-independent dilation was assessed via ultrasound imaging of the brachial artery following administration of 0.3 milligrams of sublingual nitroglycerin. A one-way analysis of variance with Bonferroni post hoc comparisons assessed sex-differences in percent peak EID dilation (EID%-peak) and EID area under the curve (EID%-AUC), while analysis of covariance (ANCOVA) adjusted for race, age, body mass index percentile (BMI-percentile), and brachial artery diameter. Multiple linear regression evaluated the association of sex, age, BMI-percentile, percent body fat (%BF), and brachial artery diameter on EID. Results: Prior to adjustment, EID%-peak was significantly higher among females than males (mean  ±  SE: 26.9  ±  0.5% versus 22.9  ±  0.6%, p  <  0.001, respectively); similar findings for EID%-AUC (4214%  ±  105%·s versus 3398%  ±  97%·s, p  <  0.001) were observed. After adjusting for covariates, EID%-AUC remained consistent (p  =  0.03) while EID%-peak was not significantly different between sexes (p  =  0.21). EID%-peak was significantly higher among normal weight compared to obese participants (p  =  0.04), while no differences were observed between obesity status after adjustment for brachial artery diameter (p  =  0.64). Both unadjusted (p  =  0.16) and adjusted EID%-AUC (p  =  0.24) was not significantly different between obesity status. BMI-percentile was not associated with EID%-peak (p  =  0.76) or EID%-AUC (p  =  0.30). Additionally, %BF was not associated with EID%-peak (p  =  0.56) or EID%-AUC (p  =  0.15). After adjusting for brachial artery diameter, BMI-percentile, and age, males had lower EID%-AUC (p  =  0.03) and lower but not significant EID%-peak (p  =  0.21). Significance: Vascular smooth muscle function was significantly lower among male children and adolescents, which is suggestive that impaired EID and increased cardiovascular disease risk among males may begin in childhood. Interestingly, obesity status and BMI-percentile was not associated with EID in children and adolescents after adjusting for brachial artery diameter. [ABSTRACT FROM AUTHOR]

Flow-mediated dilation (FMD) relies on reactive hyperemia to stimulate the endothelium to release nitric oxide, causing smooth muscle relaxation. Hypercapnia also produces vasodilation, which is thought to be nitric oxide-independent. The purpose of this study was to compare and contrast the effects of hypercapnia and reactive hyperemia as stimuli for brachial artery dilation. On separate days, twenty-five participants underwent vasodilation studies via reactive hyperemia or hypercapnia (i.e. 10 mmHg increase in end-tidal carbon dioxide [PetCO2)]). During both studies changes in brachial artery diameter were recorded using continuous ultrasound imaging. Heart rate (HR) was measured throughout both tests. Resting HR (63  ±  11 versus 68  ±  14 beats min−1, p  =  0.0027) and baseline brachial artery diameter measurements (4.57  ±  1.51 versus 5.28  ±  1.86 mm, p  =  0.022) were significantly different between reactive hyperemia and hypercapnia, respectively. HR at peak dilation (65  ±  11 versus 76  ±  14 beats min−1, p  <  0.0001), peak vessel dilation (8.68  ±  4.50 versus 5.28  ±  1.86%, p  =  0.002), and time to peak dilation (90.8  ±  120.1 versus 658.3  ±  226.6 s, p  <  0.0001) were also significantly different between reactive hyperemia and hypercapnia. The dynamics by which reactive hyperemia and hypercapnia stimulate vasodilation appear to differ. Hypercapnia produces a smaller and slower vasodilatory effect than reactive hyperemia. Further research is necessary to better understand the mechanisms of vasodilation under hypercapnic conditions. [ABSTRACT FROM AUTHOR]

Fatty acid esters of hydroxy fatty acid (FAHFA) are anti-diabetic and anti-inflammatory lipokines. Recently FAHFAs were also found to predict cardiorespiratory fitness in a cross-sectional study of recreationally trained runners. Here we report the influences of body composition and gender on static FAHFA abundances in circulation. We compared the association between circulating FAHFA concentrations and body composition, determined by dual x-ray absorptiometry, in female recreational runners who were lean (BMI < 25 kg/m2, n = 6), to those who were overweight (BMI ≥ 25 kg/m2, n = 7). To characterize the effect of gender we also compared circulating FAHFAs in lean male recreational runners (n = 8) to recreationally trained lean female (n = 6) runner group. Circulating FAHFAs were increased in females in a manner that was modulated by specific adipose depot sizes, blood glucose, and lean body mass. As expected, circulating FAHFAs were diminished in the overweight group, but strikingly, within the lean cohort, increases in circulating FAHFAs were promoted by increased fat mass, relative to lean mass, while the overweight group showed a significantly attenuated relationship. These studies suggest multimodal regulation of circulating FAHFAs and raise hypotheses to test endogenous FAHFA dynamic sources and sinks in health and disease, which will be essential for therapeutic target development. Baseline circulating FAHFA concentrations could signal sub-clinical metabolic dysfunction in metabolically healthy obesity.