Cerebral vascular responsiveness to activation of the sympathetic nervous system: impact of race

Background: Racial differences exist in the peripheral artery vasoconstrictor responsiveness in the skeletal muscle circulation to activation of the sympathetic nervous system (i.e. sympathetic vascular transduction). Specifically, the vasoconstrictor response is heightened in non-Hispanic Black (BNH) relative to non-Hispanic White (WNH) individuals. These differences may contribute to the disproportionately higher risks of hypertension and cardiac events in BNH individuals. The BNH population also has a greater risk for/prevalence of various cerebral vascular and neurocognitive diseases/conditions. However, whether this exaggerated skeletal muscle vascular transduction response also occurs in the cerebral circulation remains unknown. The Cold Pressor Test (CPT), is widely utilized to induce activation of the sympathetic nervous system and it provokes significant cardiovascular and vascular responses including vasoconstriction. The purpose of this study was to examine potential racial differences between WNH and BNH individuals in cerebral vascular response to activation of the sympathetic nervous system via the CPT. HYPOTHESIS: We hypothesized that both WNH and BNH individuals would experience cerebral vasoconstriction in response to CPT, but this response would be exaggerated in the BNH individuals. METHODS: Thirteen BNH individuals (age: 21.07 ± 3.12 years, BMI: 23.72 ± 4.17 kg/m 2 ) and nine WNH individuals (age: 21.89 ± 3.26 years, BMI: 24.67 ± 3.97 kg/m 2 ) participated in this study. Participants were positioned supine, and six minutes of baseline (BSL) measurements were recorded. Participants were then exposed to a sympathetic stimulus by submerging their hand in an ice water slurry for 2 min. Continuous measures of middle cerebral artery blood velocity (MCAVmean) and non-invasive beat-to-beat arterial blood pressure (MAP) were assessed throughout the duration of the protocol. Cerebral vascular tone was assessed as cutaneous vascular conductance (CVCi; MCAVmean/MAP) averaged during the last 30 s of the BSL and CPT periods. Results: CVCi was significantly reduced during the last 30 seconds of CPT within the BNH and WNH groups ( p <0.001, and p =0.007 respectively). However, there were no differences between BNH and WNH at either baseline ( p =0.10) or the last 30 seconds of CPT ( p =0.24) Conclusions: Our hypothesis that both WNH and BNH individuals would experience a significant decrease in CVCi was supported. However, the hypothesis that BNH individuals would exhibit a greater decrease in CVCi from baseline compared to WNH individuals was not supported. This project was supported by the University of Texas at Arlington College of Nursing and Health Innovation (RMB). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.