Nishiyasu Takeshi, Hayashida Shigeko, Kitano Asami, Nagashima Kei, Ichinose Masashi
Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Ibaraki 305-8574, Japan.
Am J Physiol Heart Circ Physiol. 2007 Jul;293(1):H670-6. doi: 10.1152/ajpheart.00462.2006. Epub 2007 Mar 9.
We tested the hypothesis that peripheral vascular responses (in the lower and upper limbs) to application of lower body positive pressure (LBPP) are dependent on the posture of the subjects. We measured heart rate, stroke volume, mean arterial pressure, leg and forearm blood flow (using the Doppler ultrasound technique), and leg (LVC) and forearm (FVC) vascular conductance in 11 subjects (9 men, 2 women) without and with LBPP (25 and 50 mmHg) in supine and upright postures. Mean arterial pressure increased in proportion to increases in LBPP and was greater in supine than in upright subjects. Heart rate was unchanged when LBPP was applied to supine subjects but was reduced in upright ones. Leg blood flow and LVC were both reduced by LBPP in supine subjects [LVC: 4.8 (SD 4.0), 3.6 (SD 3.5), and 1.4 (SD 1.8) ml.min(-1).mmHg(-1) before LBPP and during 25 and 50 mmHg LBPP, respectively; P < 0.05] but were increased in upright ones [LVC: 2.0 (SD 1.2), 3.4 (SD 3.4), and 3.0 (SD 2.0) ml.min(-1).mmHg(-1), respectively; P < 0.05]. Forearm blood flow and FVC both declined when LBPP was applied to supine subjects [FVC: 1.3 (SD 0.6), 1.0 (SD 0.4), and 0.9 (SD 0.6) ml. min(-1).mmHg(-1), respectively; P < 0.05] but remained unchanged in upright ones [FVC: 0.7 (SD 0.4), 0.7 (SD 0.4), and 0.6 (SD 0.5) ml.min(-1).mmHg(-1), respectively]. Together, these findings indicate that the leg vascular response to application of LBPP is posture dependent and that the response differs in the lower and upper limbs when subjects assume an upright posture.
我们验证了这样一个假设，即下身正压（LBPP）作用下（下肢和上肢的）外周血管反应取决于受试者的姿势。我们测量了11名受试者（9名男性，2名女性）在仰卧位和直立位时，在无LBPP以及有LBPP（25和50 mmHg）情况下的心率、心输出量、平均动脉压、腿部和前臂血流量（使用多普勒超声技术），以及腿部（LVC）和前臂（FVC）血管传导率。平均动脉压随LBPP的增加而成比例升高，且仰卧位受试者的升高幅度大于直立位受试者。对仰卧位受试者施加LBPP时心率不变，但对直立位受试者施加LBPP时心率降低。仰卧位受试者的腿部血流量和LVC均因LBPP而降低[LVC：LBPP施加前、25 mmHg LBPP时和50 mmHg LBPP时分别为4.8（标准差4.0）、3.6（标准差3.5）和1.4（标准差1.8）ml·min⁻¹·mmHg⁻¹；P < 0.05]，但直立位受试者的腿部血流量和LVC均增加[LVC：分别为2.0（标准差1.2）、3.4（标准差3.4）和3.0（标准差2.0）ml·min⁻¹·mmHg⁻¹；P < 0.05]。对仰卧位受试者施加LBPP时，前臂血流量和FVC均下降[FVC：分别为1.3（标准差0.6）、1.0（标准差0.4）和0.9（标准差0.6）ml·min⁻¹·mmHg⁻¹；P < 0.05]，但直立位受试者的前臂血流量和FVC保持不变[FVC：分别为0.7（标准差0.4）、0.7（标准差0.4）和0.6（标准差0.5）ml·min⁻¹·mmHg⁻¹]。总之，这些发现表明，腿部对LBPP施加的血管反应取决于姿势，并且当受试者处于直立姿势时，下肢和上肢的反应有所不同。
