Potential Effects of Sex on Vascular Dysfunction in Young Black Individuals
Authors: Akins John D. , Patik Jordan C. , Curtis Bryon M. , Nasirian Aida , Olvera Guillermo , Fadel Paul J. , Brothers R. Matthew 
Published: June 2021

The black population has a higher prevalence of hypertension (HTN) than age‐matched whites. Importantly, within racial groups there is also a sex disparity in HTN prevalence; black women (BW) have a higher prevalence compared to black men (BM), whereas white women (WW) have a lower prevalence than white men (WM). While the causes of this divergence in prevalence are multifactorial, vascular dysfunction likely contributes to this racial disparity. Previous studies have demonstrated lower flow‐mediated dilation (FMD), an index of conduit artery function, and blunted reactive hyperemia (RH), an index of microvascular function, in blacks compared to whites suggesting a diminished overall vascular function in this population. Additionally, compared to WM, WW exhibit an augmented FMD indicative of better conduit artery function; however, this sex difference does not exist in the black population. Importantly, BM have attenuated microvascular function as demonstrated by a reduced RH; however, the RH response in BW remains unclear. Therefore, the present study tested the hypothesis that both BM and BW would have a reduced RH response relative to their white counterparts. FMD and RH responses were measured in 8 WM, 7 WW, 8 BM, and 6 BW (mean±SD age; 23±3, 23±2, 26±3, and 23±3 y, respectively). Women were studied during the early follicular phase (days 2–7). Participants abstained from strenuous exercise, alcohol, and caffeine for 24‐h and fasted overnight preceding the study. Following 15‐min of supine rest, FMD and RH responses were assessed. A rapid inflation cuff was secured to the forearm just distal to the elbow for arterial occlusion. Brachial artery diameter and blood velocity were continuously measured via duplex Doppler ultrasound during two‐min of baseline followed by 5‐min of occlusion at 220 mmHg and 3‐min of recovery. FMD was greater in WW than WM (11.4±2.6 vs. 5.6±3.1%; P=0.04); however, there was no difference in the response between BW and BM (7.3±2.2 and 7.4±3.3%, respectively; P=0.40). Furthermore, FMD was greater in WW than BW (P=0.04), but not different between WM and BM (p=0.40). The total RH area under the curve (AUC) in the 120‐sec following cuff release was attenuated in BM compared to WM (AUC: 644±239 vs. 954 ±353 ml; P=0.05), but there was no difference between BW and WW (484±208 vs. 487±179 ml; P=0.99). Likewise, peak blood flow during RH was reduced in BM compared to WM (561.3±193 vs. 896.4±393 ml/min; P=0.03). However, there was no difference in peak flow between BW and WW (500±199 vs. 454 ±165 ml/min; P=0.94). These preliminary data suggest that sex differences exist in vascular function of apparently healthy, young blacks. Young BM exhibit microvascular dysfunction, yet seem to possess no evidence of impairment in conduit artery vasodilation. In contrast, vascular dysfunction in young BW seems to be more influenced at the conduit artery level as their FMD response was attenuated despite a similar RH, and thus, microvascular function, compared to WW.Support or Funding InformationSupported by UTA College of Nursing and Health Innovation.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.