Antecubital venous endothelial ETB receptor protein expression is preserved with aging in men.

Changes in endothelial function precede the development of cardiovascular disease (CVD). We have previously shown that age-related declines in endothelial function in women are due in part to a reduction in endothelial cell endothelin-B receptor (ETBR) protein expression. However, it is not known if ETBR protein expression changes with aging in men. The purpose of this study was to test the hypothesis that ETBR protein expression is attenuated in older men (OM) compared with younger men (YM). Primary endothelial cells were harvested from the antecubital vein of 14 OM (60 ± 6 yr; 26 ± 3 kg/m2) and 17 YM (24 ± 5 yr; 24 ± 2 kg/m2). Cells were stained with 4',6-diamidino-2-phenylindole, vascular endothelial cadherin, and ETBR. Images were quantified using immunocytochemistry. Endothelial function was assessed using brachial artery flow-mediated dilation (FMD). Systolic BP was similar (OM, 123 ± 11 vs. YM, 122 ± 10 mmHg) whereas diastolic BP was higher in OM (OM, 77 ± 7 vs. YM, 70 ± 6 mmHg; P < 0.01). Total testosterone was lower in OM (OM, 6.28 ± 4.21 vs. YM, 9.10 ± 2.68 ng/mL; P = 0.03). As expected, FMD was lower in OM (OM, 3.85 ± 1.51 vs. YM, 6.40 ± 2.68%; P < 0.01). However, ETBR protein expression was similar between OM and YM (OM, 0.39 ± 0.17 vs. YM, 0.42 ± 0.17 AU; P = 0.66). These data suggest that ETBR protein expression is not altered with age in men. These findings contrast with our previous data in women and further support sex differences in the endothelin system.NEW & NOTEWORTHY Our laboratory has previously shown that age-related declines in endothelial function are associated with a reduction in endothelial cell ETBR protein expression in women. However, it is unclear if endothelial cell ETBR protein expression is reduced with aging in men. This study demonstrates that endothelial cell ETBR protein expression is preserved with aging in men, and provides additional evidence for sex differences in the endothelin system.

Oxygen Consumption and Blood Pressure Are Not Influenced by Use of a Backpack Hip Strap.

INTRODUCTION: Several studies have explored the effect of backpack carriage on physiologic responses while walking, but few have focused specifically on the influence of the use of a hip strap on these responses. The aim of this study was to investigate the effect of a backpack hip strap on physiologic responses when walking at a moderate intensity while carrying a backpack with a standardized relative load of 30% of the wearer's body mass. METHODS: Twenty-three healthy, active participants carrying backpacks walked on a treadmill at a speed and grade that elicited 40-50% of their heart rate reserve. Participants completed 2 counterbalanced 30-min trials, one with the hip strap in the strapped condition and one with the hip strap unfastened. Metabolic, heart rate, blood pressure, and muscle oxygen saturation (SmO2) responses were recorded during both trials. For each variable, 5-min intervals were averaged at baseline, 5, 10, 15, 20, 25, and 30 min. A repeated measures ANOVA test was used to evaluate the differences between the conditions at each time point. Data reported are the values from the final 5-min interval (30 min) and are reported as mean±SD. RESULTS: No differences were found between strapped and unstrapped trials for oxygen consumption (strapped 21.9±4.2 mL·kg-1·min-1; unstrapped 22.0±4.4 mL·kg-1·min-1, P=0.842), Δmean arterial pressure (strapped +5±17 Δmm Hg; unstrapped +12±14 Δmm Hg, P=0.128) or muscle oxygen saturation of the quadriceps (strapped 86±15%; unstrapped 90±12%, P=0.359) and calf (strapped 73±19%; unstrapped 81±12%, P=0.888). CONCLUSIONS: These results suggest that wearing a hip strap does not influence physiologic responses up to 30 min of moderate intensity walking while carrying 30% of the wearer's mass.