Inhibition of superoxide and iNOS augment cutaneous nitric oxide‐dependent vasodilation in non‐Hispanic black young adults

Abstract

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.