Sympathetic-Cardiovascular Relationships in Young Black Males

Given the elevated risk of hypertension in non-Hispanic black (BL) males, there is a growing interest in studying racial differences in the sympathetic regulation of blood pressure. Research, primarily done in non-Hispanic white (WH) males, suggests that at rest mean arterial pressure (MAP) and muscle sympathetic nerve activity (MSNA) have no correlation, whereas total peripheral resistance (TPR) is positively correlated with MSNA, and cardiac output (CO) is negatively correlated with MSNA. However, it is unknown if these relationships exist in BL males. Accordingly, the purpose of this investigation was to determine the extent to which MSNA is correlated with resting MAP, TPR, and CO in young healthy BL males. Heart rate (ECG), beat-to-beat blood pressure (finometer), and MSNA (peroneal microneurography) were continuously recorded during 10 minutes of quiet supine rest in 47 young healthy males (21 BL males and 26 WH males; average age: 24 ± 4 years; BMI: 25.0 ± 3.1 kg/m 2 ). Modelflow was used to estimate stroke volume (SV) and then subsequently calculate CO (SV * Heart Rate) and TPR (MAP/CO). Resting MAP was similar between BL and WH males (BL: 88 ± 7 mmHg; WH: 84 ± 8 mmHg; P = 0.18), whereas resting MSNA burst frequency was lower in BL males (BL: 12 ± 6 bursts/min; WH: 16 ± 7 bursts/min; P = 0.04). Calculated TPR at rest was greater in BL compared to WH males (P = 0.006), while resting heart rate, and CO were not different between groups (both P > 0.05). In young BL males, MSNA was not correlated to resting MAP, TPR, or CO (all P > 0.05). In young WH males, MSNA was not correlated to MAP (P > 0.05) but was positively correlated to TPR (r = 0.52, P = 0.007), and negatively correlated to CO (r = -0.43, P = 0.03). Collectively, these preliminary data suggest that in young BL males, similar to WH males, resting MSNA is not related with resting MAP. However, in contrast to WH males, no MSNA relationships with TPR, or CO were found in BL males. These preliminary findings identify potential racial differences in the sympathetic support of resting BP in young males. This work was supported by the College of Nursing and Health Innovation and the Undergraduate Research Opportunity Program at the University of Texas at Arlington. 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.