Penn State Heart and Vascular Institute, H047, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, 500 University Drive, PO Box 850, Hershey, PA 17033, USA.
Eur J Appl Physiol. 2011 Jul;111(7):1415-20. doi: 10.1007/s00421-010-1769-z. Epub 2010 Dec 15.
To examine the role of limb posture on vascular conductance during rapid changes in vascular transmural pressure, we determined brachial (n = 10) and femoral (n = 10) artery post-occlusive reactive hyperemic blood flow (RHBF, ultrasound/Doppler) and vascular conductance in healthy humans with each limb at three different positions-horizontal, up and down. Limb posture was varied by raising or lowering the arm or leg from the horizontal position by 45°. In both limbs, peak RHBF and vascular conductance were highest in the down or horizontal position and lowest in the up position (arm up 338 ± 38, supine 430 ± 52, down 415 ± 52 ml/min, P < 0.05; leg up 1,208 ± 88, supine 1,579 ± 130, down 1,767 ± 149 ml/min, P < 0.05). In contrast, the maximal dynamic fall in blood flow following peak RHBF (in ml/s/s) in both limbs was highest in the limb-down position and lowest with the limb elevated (P < 0.05). These data suggest that the magnitude and temporal pattern of limb reactive hyperemia is in part related to changes in vascular transmural pressure and independent of systemic blood pressure and sympathetic control.
为了研究血管跨壁压力快速变化时肢体姿势对血管传导性的作用，我们在健康人群中确定了肱动脉（n = 10）和股动脉（n = 10）的闭塞后反应性充血血流（RHBF，超声/多普勒）和血管传导性，每个肢体处于三种不同位置——水平、向上和向下。通过将手臂或腿部从水平位置抬高或降低 45°来改变肢体姿势。在两个肢体中，RHBF 和血管传导性的峰值在向下或水平位置最高，向上位置最低（手臂向上 338 ± 38，仰卧 430 ± 52，向下 415 ± 52 ml/min，P < 0.05；腿部向上 1,208 ± 88，仰卧 1,579 ± 130，向下 1,767 ± 149 ml/min，P < 0.05）。相比之下，在两个肢体中，RHBF 峰值后血流的最大动态下降（以 ml/s/s 为单位）在肢体向下位置最高，而在肢体抬高时最低（P < 0.05）。这些数据表明，肢体反应性充血的幅度和时间模式部分与血管跨壁压力的变化有关，而与系统血压和交感神经控制无关。
