Vascular Responses to Hand Posture are Preserved Despite Acute Endothelial Dysfunction: Insights from Pulse Wave Velocity and Finger-to-Finger Timing

Limb posture alters hydrostatic pressure and vascular tone through mechanical and reflex pathways, but the contribution of endothelial function remains uncertain. To determine whether vascular responses to hand elevation and dependency persist during transient endothelial dysfunction induced by ischemia–reperfusion injury (IRI), eighteen healthy adults (9 males, 9 females) underwent ECG-gated pulse recordings at three hand positions: heart level (H-0°), 90° below (H-90°), and 50° above (H+50°), before and after IRI. Primary outcomes were pulse wave velocity (PWV) and finger-to-finger pulse arrival-time difference (f–f ΔT); secondary outcomes were wrist mean blood pressure (MBP), heart rate (HR), and ΔPWV/ΔBP slope. The result at baseline, hand elevation reduced PWV by 10–13% and increased f–f ΔT by 600–727%, while dependency increased PWV by ~7% and decreased f–f ΔT by ~200%. After IRI, these postural responses persisted, with only a modest 3% PWV reduction at H-90° and H-0° (p < 0.05). MBP shifted with posture as expected, and HR rose slightly with dependency but decreased overall after IRI. The ΔPWV/ΔBP slope was steeper in elevation, consistent with enhanced compliance. In conclusion, vascular responses to hand posture remain preserved despite acute endothelial dysfunction, indicating that short-term postural adjustments in arterial stiffness are mediated predominantly by hydrostatic and reflex mechanisms rather than endothelial pathways.