The effect of endothelin a receptor inhibition and biological sex on cutaneous microvascular function in non‐Hispanic Black and White young adults

Abstract The purpose of this study was to investigate whether endothelin‐A receptor (ET A R) inhibition in non‐Hispanic Black (NHB) and White (NHW) young adults depends on biological sex. We recruited females during low hormone ( n = 22) and high hormone ( n = 22) phases, and males ( n = 22). Participants self‐identified as NHB ( n = 33) or NHW ( n = 33). Participants were instrumented with two microdialysis fibers: (1) lactated Ringer's (control) and (2) 500 nM BQ‐123 (ET A R antagonist). Local heating was used to elicit cutaneous vasodilation, and an infusion of 20 mM L‐NAME to quantify NO‐dependent vasodilation. At control sites, NO‐dependent vasodilation was lowest in NHB males (46 ± 13 %NO) and NHB females during low hormone phases (47 ± 12 %NO) compared to all NHW groups. Inhibition of ET A R increased NO‐dependent vasodilation in NHB males (66 ± 13 %NO), in both groups of females during low hormone phases (NHW, control: 64 ± 12 %NO, BQ‐123: 85 ± 11 %NO; NHB, BQ‐123: 68 ± 13 %NO), and in NHB females during high hormone phases (control: 61 ± 11 %NO, BQ‐123: 83 ± 9 %NO). There was no effect for ET A R inhibition in NHW males or females during high hormone phases. These data suggest the effect of ET A R inhibition on NO‐dependent vasodilation is influenced by biological sex and racial identity.