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 (ET_BR) protein expression. However, it is not known if ET_BR protein expression changes with aging in men. The purpose of this study was to test the hypothesis that ET_BR 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 ET_BR. 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, ET_BR 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 ET_BR 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 ET_BR protein expression in women. However, it is unclear if endothelial cell ET_BR protein expression is reduced with aging in men. This study demonstrates that endothelial cell ET_BR protein expression is preserved with aging in men, and provides additional evidence for sex differences in the endothelin system.