Augmented beat-to-beat blood pressure variability in early middle-aged non-Hispanic Black females

Non-Hispanic Black (BL) males and females have the highest prevalence of cardiovascular disease compared to all other racial or ethnic groups in the United States. Previous work from our laboratory has shown that beat-to-beat blood pressure variability (BPV), a known predictor of adverse cardiovascular events, was augmented in young BL males but not in young BL females. To extend this work, herein, we examined beat-to-beat BPV during early middle-age in BL females. We also assessed sympathetic baroreflex sensitivity (sBRS), an important regulator of beat-to-beat blood pressure and total peripheral resistance (TPR) variability. We tested the hypothesis that early middle-aged BL females exhibit greater beat-to-beat BPV compared to young BL females, which would be accompanied by lower sBRS and greater TPR variability. Beat-to-beat blood pressure (finger photoplethysmography), brachial blood pressure (brachial oscillometry), and muscle sympathetic nerve activity (MSNA; peroneal microneurography) were measured in 7 premenopausal early middle-aged (Age: 43±2 years, BMI: 30.0±6.2 kg/m 2 ) and 12 young (Age: 20±2 years, BMI: 24.4±3.5 kg/m 2 ) BL females during 10 minutes of quiet supine rest. Beat-to-beat BPV was determined through calculations of standard deviation (SD), range, coefficient of variation (CV), and interquartile range (IQR) for systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP). Stroke volume (SV) was estimated using Modelflow, then cardiac output (CO = SV x Heart rate) and total peripheral resistance (TPR = MAP / CO) were calculated and CO and TPR variability were determined. sBRS was quantified by sorting all resting DBPs into 3 mmHg bins and calculating MSNA burst incidence within each bin. Weighted linear regression was then used to calculate slopes. Resting absolute SBP, DBP, and MAP were greater in middle-aged females (all P< 0.05). Beat-to-beat MAP variability was greater in middle-aged females for SD (Middle-Aged: 5.0±1.5; Young: 3.3±1.0 mmHg; P=0.009), range (Middle-Aged: 28±7; Young: 20±6 mmHg; P=0.014), and IQR (Middle-Aged: 7±2; Young: 4±2 mmHg; P=0.003), with no difference in CV (P >0.05). Further, middle-aged females trended towards having a greater TPR variability for SD (Middle-Aged: 1.4±0.4; Young: 1.0±0.4 mmHg*min/L; P=0.086) and had a greater TPR IQR (Middle-Aged: 1.9±0.6; Young: 1.3±0.5 mmHg*min/L; P=0.042), with no differences in any CO variability measure (all P >0.05). sBRS gain was not different between the groups (Middle-Aged: -3.5±0.8 bursts/100 heartbeats/mmHg; Young: -5.0±2.2 bursts/100 heartbeats/mmHg; P=0.177). All SBP variability measures were greater in middle-aged females compared to young (all P< 0.05), whereas only DBP IQR was greater in middle-aged females (P=0.0114). These preliminary data suggest that beat-to-beat BPV is greater in early middle-aged BL females than in young BL females and these differences may be driven by a greater TPR variability. This abstract was presented at the American Physiology Summit 2026 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.