Differential Responses of Resistance Arterioles to Elevated Intraluminal Pressure in Blacks and Whites.

Black Americans have an earlier onset, higher average blood pressure, and higher rates of hypertension-related mortality and morbidity, compared to whites. The racial difference may be related to microvasculature, the major regulatory site of blood pressure. The goal of this study was to compare the response of resistance vessels to high intraluminal pressure between black and white participants. A total of 38 vessels were obtained from human fat samples (21 black, 17 white; mean age 32 ± 12 years and BMI 26.9 ± 4.9; between-group P ≥ 0.05) and included in this study. Internal diameter was measured in response to flow induced by various pressure gradients (Δ10, Δ20, Δ40, Δ60, and Δ100 cmH2O), and flow-induced dilation (FID) was calculated before and after high intraluminal pressure (150 cm H2O). Prior to high intraluminal pressure, FID was not different between blacks and whites (P = 0.112). After exposure to high intraluminal pressure, FID was reduced at every pressure gradient in vessels from blacks (P < 0.001), while FID did not change in white participants except at Δ 100 cmH2O. When incubated with the H2O2 scavenger PEG-catalase, the FID response in vessels from black, but not white, individuals was significantly reduced and the magnitude was higher at normal pressure relative to high pressure. Our findings suggest that vessels from self-identified black individuals are more susceptible to microvascular dysfunction following transient periods of high intraluminal pressure compared to whites and show greater dependence on H2O2 as a main contributor to FID at normal pressures.