Responses of total peripheral resistance to standing in orthostatic hypertension

Background: Orthostatic hypertension (OHT), defined by a significant rise in blood pressure (BP) upon standing, has been identified as a risk factor for adverse cardiovascular events. However, the hemodynamic mechanisms underlying the maintenance of upright BP in OHT remain unclear. In particular, the contribution of total peripheral resistance (TPR) to the OHT response has not been characterized. Therefore, this study tested the hypothesis that individuals with OHT exhibit a greater TPR response to standing compared with controls. Methods: Adult volunteers without known cardiovascular disease underwent a 10-minute supine rest followed by a 10-minute active standing test, during which continuous beat-by-beat heart rate (HR; ECG) and BP (Finometer, referenced to heart level) were recorded. Brachial cuff BP was measured every 2 minutes. Groups were classified based on the brachial cuff-derived change in systolic BP (SBP): OHT (ΔSBP ≥ +10 mmHg upon standing, N = 36), Maintained BP (Control; ΔSBP −5 to +8 mmHg, N = 61), and an “Other” category that was not analyzed as a primary group. Mean values of beat-by-beat SBP, stroke volume (SV), cardiac output (CO), and TPR from Finometer during each test stage were used for analysis. The relationship between beat-by-beat SBP and SV was assessed using linear regression. Results: A total of 115 participants (40 ± 15 years, 32 M/82 F) were examined in this study. The increase in SBP during standing was greater in the OTH group compared with controls (p < 0.001). HR increased similarly between groups (group × posture interaction, p = 0.63). Both SV (Δ−35.7 vs Δ −30.3 mL, p < 0.001) and CO (Δ−1.70 vs Δ −1.26 L·min - ¹, p< 0.001) decreased more in the OTH group. TPR rose in both groups but to a greater extent in OTH (Δ661 vs. Δ427 dyn·s·cm - 5 , p< 0.001). Coupling analyses revealed flatter SV–SBP slopes and lower intercepts during standing, with a significant between-group difference in the upright slope (p = 0.0008). Discussion and Conclusion: Our data demonstrate that the increase in TPR during standing is greater in subjects with OTH than in control subjects, despite larger reductions in SV and CO, and comparable HR responses. These findings suggest that individuals with OTH may exhibit an exaggerated vasoconstrictor response. Together with our previous observation that cardiovagal baroreflex function is impaired in OTH, the present results support a mechanistic model of accentuated sympathetic–vascular compensation in these individuals and underscore the need for future studies incorporating direct autonomic measurements and interventional approaches. Funded by NIH R01HL144781 and R01HL164571) 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.