Antecubital Venous Endothelial ETB Receptor Protein Expression is Preserved with Aging in Men

Abstract

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 to younger men (YM). Primary endothelial cells were harvested from the antecubital vein of 14 OM (60±6 yrs; 26±3 kg/m2) and 17 YM (24±5 yrs; 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 ±2.68ng/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 are in contrast to our previous data in women, and further support sex differences in the endothelin system.