Sensory Nerve‐Mediated and Nitric Oxide‐Dependent Vasodilation Is Reduced in Non‐Hispanic Blacks Compared to Non‐Hispanic Whites

Abstract

Reduced microvascular function is recognized in healthy non‐Hispanic Blacks compared to non‐Hispanic Whites, but it is unclear whether sensory nerve function is altered in non‐Hispanic Blacks. Local heating of the skin allows for the simultaneous assessment of both sensory nerve‐mediated and nitric oxide (NO)‐dependent vasodilation. The purpose of this study was to test the hypothesis that the magnitude of cutaneous sensory nerve‐mediated and microvascular endothelial‐dependent vasodilation is reduced in non‐Hispanic Blacks compared to non‐Hispanic Whites. Six healthy participants who self‐identified as non‐Hispanic Black (n=3) or non‐Hispanic White (n=3) were instrumented with two microdialysis fibers on the forearm: 1) lactated Ringer's (control) and 2) topical anesthetic (5% lidocaine) to inhibit sensory nerve function. A rapid local heating protocol was conducted at each microdialysis site where the temperature of the skin was heated from 33°C to 39°C at a rate of 1°C/sec. Skin blood flow was continuously monitored at each site with laser‐Doppler flow (LDF) probes. At the plateau of skin blood flow, 20 mM L‐NAME was perfused at each site to inhibit NO synthase in order to calculate %NO‐dependent vasodilation. Following L‐NAME infusion, maximal skin blood flow was reached by infusing each site with 54 mM sodium nitroprusside and heating the skin to 43°C. Cutaneous vascular conductance (CVC) was calculated (LDF/MAP) and standardized to maximal blood flow (%CVCmax). Data shown are mean ± SD. At control sites, the initial peak (33 ± 9 %CVCmax) and plateau (52 ± 9 %CVCmax) in non‐Hispanic Blacks were reduced compared to non‐Hispanic Whites (53 ± 8 % and 67 ± 10 %CVCmax; P < 0.05 for all conditions). At sites treated with anesthetic, the initial peak was unaltered in non‐Hispanic Blacks (26 ± 10 %CVCmax) but was significantly reduced in non‐Hispanic Whites (23 ± 13 %CVCmax). Anesthetic did not affect the plateau in either non‐Hispanic Blacks (56 ± 5 %CVCmax) or non‐Hispanic Whites (62 ± 4 %CVCmax). Calculated %NO‐dependent vasodilation was reduced in non‐Hispanic Blacks (51 ± 6 %NO) compared to non‐Hispanic Whites (67 ± 8 %NO). These data indicate that sensory nerve function, microvascular function, and NO‐dependent vasodilation are all decreased in non‐Hispanic Blacks in comparison to non‐Hispanic Whites.Support or Funding InformationNIH R01HL141205This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.