Flow‐mediated dilation responses to exogenous testosterone administration in healthy males

We investigated the independent contributions of the peak and continued reactive hyperemia on flow-mediated dilation (FMD). 1) For the duration manipulation experiment (DME), 10 healthy males experienced reactive hyperemia durations of 10 s, 20 s, 30 s, 40 s, 50 s, or full reactive hyperemia (RH). 2) For the peak manipulation experiment (PME), eight healthy males experienced reactive hyperemia trials with three peak shear rate magnitudes (large, medium, and small). Data are means ± SD. For the DME, peak shear rate was not different between trials ( P = 0.326). Shear rate area under the curve (AUC) was P < 0.001. Peak %FMD was dependent on shear rate AUC: 10 s, 2.7 ± 1.3; 20 s, 6.2 ± 1.9; 30 s, 7.9 ± 2.9; 40 s, 8.3 ± 3.2; 50 s, 7.9 ± 3.2; full RH, 9.3 ± 4.1, with 10 and 20 s less than full RH ( P < 0.001). For the PME, peak shear rate was different between trials (large, 1,049.1 ± 285.8; medium, 726.4 ± 228.8; small, 512.8 ± 161.8; P < 0.001). AUC of the continued shear rate was not ( P = 0.412). Peak %FMD was unaffected by peak shear rate (large, 7.0 ± 2.7%; medium, 7.4 ± 2.6%; small, 6.6 ± 1.8%; P = 0.542). Peak and AUC shear stimulus were not significantly related in full RH ( r2 = 0.35, P = 0.07). We conclude that the shear stimulus AUC, not the peak itself, is the critical determinant of the peak FMD response. This indicates AUC as the best method of quantifying reactive hyperemia shear stimulus for %FMD normalization.

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The Effect of Testosterone Administration and Digit Ratio (2D:4D) on Implicit Preference for Status Goods in Healthy Males

Frontiers in Behavioral Neuroscience ◽

10.3389/fnbeh.2017.00193 ◽

2017 ◽

Vol 11 ◽

Cited By ~ 5

Author(s):

Yin Wu ◽

Samuele Zilioli ◽

Christoph Eisenegger ◽

Luke Clark ◽

Hong Li

Keyword(s):

Digit Ratio ◽

Status Goods ◽

Testosterone Administration ◽

Healthy Males

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The impact of an acute oral phosphate load on endothelium dependent and independent brachial artery vasodilation in healthy males

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2017-0147 ◽

2017 ◽

Vol 42 (12) ◽

pp. 1307-1315 ◽

Cited By ~ 5

Author(s):

Brendan M. Levac ◽

Michael A. Adams ◽

Kyra E. Pyke

Keyword(s):

Brachial Artery ◽

Fractional Excretion ◽

Serum Phosphate ◽

Flow Mediated Dilation ◽

Primary Analysis ◽

Cardiovascular Morbidity And Mortality ◽

Dependent Flow ◽

Fractional Excretion Of Phosphate ◽

The Impact ◽

Healthy Males

Serum phosphate levels are associated with cardiovascular morbidity and mortality in the general population and endothelial dysfunction may be mechanistically involved. The purpose of this study was to investigate the effects of acute phosphate supplementation on endothelial-dependent (flow-mediated dilation; FMD) and -independent (glyceryl trinitrate; GTN)) vasodilation in young, healthy males. Seventeen healthy male participants (age, 23 ± 3 years) were exposed to an oral load of phosphate (PHOS; liquid supplement containing 1200 mg of phosphorous) and placebo (PLAC) over 2 experimental days. A brachial artery FMD test was performed pre-ingestion and at 20 min, 60 min, and 120 min following the ingestion of the phosphate load or the placebo. GTN tests were performed pre- and 140 min post-ingestion. Serum phosphate was not impacted differently by phosphate versus placebo ingestion (p = 0.780). In contrast, urinary phosphate excretion was markedly increased in the PHOS (p < 0.001) but not in the PLAC condition (p = 0.130) (Δ fractional excretion of phosphate in PHOS (29.2%) vs. PLAC (9.3%)). This indicates that circulating phosphate levels were homeostatically regulated. GTN-mediated vasodilation was not significantly affected by phosphate ingestion. In primary analysis no impact of phosphate ingestion on FMD was detected. However, when the shear stress stimulus was added as a covariate in a subset of participants, exploratory pairwise comparisons revealed a significantly lower FMD 20 min post-phosphate ingestion versus placebo (p = 0.024). The effects of phosphate ingestion on FMD and serum phosphate are in contrast with previous findings and the mechanisms that underlie the disparate results require further investigation.

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Dietary Nitrate Supplementation and 3-weeks Sprint Interval Training Improves Flow Mediated Dilation in Healthy Males

Medicine & Science in Sports & Exercise ◽

10.1249/01.mss.0000485775.36248.31 ◽

2016 ◽

Vol 48 ◽

pp. 257

Author(s):

David J. Muggeridge ◽

Nicholas Sculthorpe ◽

Philip E. James ◽

Chris Easton

Keyword(s):

Interval Training ◽

Flow Mediated Dilation ◽

Sprint Interval Training ◽

Dietary Nitrate ◽

Nitrate Supplementation ◽

Healthy Males

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Detection of Epitestosterone Doping by Isotope Ratio Mass Spectrometry

Clinical Chemistry ◽

10.1093/clinchem/48.4.629 ◽

2002 ◽

Vol 48 (4) ◽

pp. 629-636 ◽

Cited By ~ 57

Author(s):

Rodrigo Aguilera ◽

Caroline K Hatton ◽

Don H Catlin

Keyword(s):

Mass Spectrometry ◽

Gas Chromatography ◽

Isotope Ratio ◽

Isotope Ratio Mass Spectrometry ◽

Urine Samples ◽

Control Group ◽

Δ13c Values ◽

Testosterone Administration ◽

The Mean ◽

Healthy Males

Abstract Background: Epitestosterone is prohibited by sport authorities because its administration will lower the urinary testosterone/epitestosterone ratio, a marker of testosterone administration. A definitive method for detecting epitestosterone administration is needed. Methods: We developed a gas chromatography-combustion-isotope ratio mass spectrometry method for measuring the δ13C values for urinary epitestosterone. Sample preparation included deconjugation with β-glucuronidase, solid-phase extraction, and semipreparative HPLC. Epitestosterone concentrations were determined by gas chromatography-mass spectrometry for urines obtained from a control group of 456 healthy males. Epitestosterone δ13C values were determined for 43 control urines with epitestosterone concentrations ≥40 μg/L (139 nmol/L) and 10 athletes’ urines with epitestosterone concentrations ≥180 μg/L (624 nmol/L), respectively. Results: The log epitestosterone concentration distribution was gaussian [mean, 3.30; SD, 0.706; geometric mean, 27.0 μg/L (93.6 nmol/L)]. The δ13C values for four synthetic epitestosterones were low (less than or equal to −30.3‰) and differed significantly (P <0.0001). The SDs of between-assay precision studies were low (≤0.73‰). The mean δ13C values for urine samples obtained from 43 healthy males was −23.8‰ (SD, 0.93‰). Nine of 10 athletes’ urine samples with epitestosterone concentrations >180 μg/L (624 nmol/L) had δ13C values within ± 3 SD of the control group. The δ13C value of epitestosterone in one sample was −32.6‰ (z-score, 9.4), suggesting that epitestosterone was administered. In addition, the likelihood of simultaneous testosterone administration was supported by low δ13C values for androsterone and etiocholanolone. Conclusions: Determining δ13C values for urinary epitestosterone is useful for detecting cases of epitestosterone administration because the mean δ13C values for a control group is high (−23.8‰) compared with the δ13C values for synthetic epitestosterones.

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