LAUSR

We assessed the combined effect of superoxide and iNOS inhibition on microvascular function in non‐Hispanic Black and non‐Hispanic White participants (n = 15 per group). Participants were instrumented with four microdialysis fibers: (1) lactated Ringer's (control), (2) 10 μM tempol (superoxide inhibition), (3) 0.1 mM 1400 W (iNOS inhibition), (4) tempol + 1400 W. Cutaneous vasodilation was induced via local heating and NO‐dependent vasodilation was quantified. At control sites, NO‐dependent vasodilation was lower in non‐Hispanic Black (45 ± 9% NO) relative to non‐Hispanic White (79 ± 9% NO; p < 0.01; effect size, d = 3.78) participants. Tempol (62 ± 16% NO), 1400 W (78 ± 12% NO) and tempol +1400 W (80 ± 13% NO) increased NO‐dependent vasodilation in non‐Hispanic Black participants relative to control sites (all p < 0.01; d = 1.22, 3.05, 3.03, respectively). The effect of 1400 W (p = 0.04, d = 1.11) and tempol +1400 W (p = 0.03, d = 1.22) was greater than tempol in non‐Hispanic Black participants. There was no difference between non‐Hispanic Black and non‐Hispanic White participants at 1400 W or tempol + 1400 W sites. These data suggest iNOS has a greater effect on NO‐dependent vasodilation than superoxide in non‐Hispanic Black participants.