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 (ETR) protein expression. However, it is not known if ETR protein expression changes with aging in men. The purpose of this study was to test the hypothesis that ETR 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/m) and 17 YM (24 ± 5 yr; 24 ± 2 kg/m). Cells were stained with 4',6-diamidino-2-phenylindole, vascular endothelial cadherin, and ETR. 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; < 0.01). Total testosterone was lower in OM (OM, 6.28 ± 4.21 vs. YM, 9.10 ± 2.68 ng/mL; = 0.03). As expected, FMD was lower in OM (OM, 3.85 ± 1.51 vs. YM, 6.40 ± 2.68%; < 0.01). However, ETR protein expression was similar between OM and YM (OM, 0.39 ± 0.17 vs. YM, 0.42 ± 0.17 AU; = 0.66). These data suggest that ETR 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. Our laboratory has previously shown that age-related declines in endothelial function are associated with a reduction in endothelial cell ETR protein expression in women. However, it is unclear if endothelial cell ETR protein expression is reduced with aging in men. This study demonstrates that endothelial cell ETR protein expression is preserved with aging in men, and provides additional evidence for sex differences in the endothelin system.