Yavorcik K J, Reighard D A, Misra S P, Cotter L A, Cass S P, Wilson T D, Yates B J
Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
Am J Physiol Regul Integr Comp Physiol. 2009 Dec;297(6):R1777-84. doi: 10.1152/ajpregu.00551.2009. Epub 2009 Sep 30.
Considerable data show that the vestibular system contributes to blood pressure regulation. Prior studies reported that lesions that eliminate inputs from the inner ears attenuate the vasoconstriction that ordinarily occurs in the hindlimbs of conscious cats during head-up rotations. These data led to the hypothesis that labyrinthine-deficient animals would experience considerable lower body blood pooling during head-up postural alterations. The present study tested this hypothesis by comparing blood flow though the femoral artery and vein of conscious cats during 20-60 degrees head-up tilts from the prone position before and after removal of vestibular inputs. In vestibular-intact animals, venous return from the hindlimb dropped considerably at the onset of head-up tilts and, at 5 s after the initiation of 60 degrees rotations, was 66% lower than when the animals were prone. However, after the animals were maintained in the head-up position for another 15 s, venous return was just 33% lower than before the tilt commenced. At the same time point, arterial inflow to the limb had decreased 32% from baseline, such that the decrease in blood flow out of the limb due to the force of gravity was precisely matched by a reduction in blood reaching the limb. After vestibular lesions, the decline in femoral artery blood flow that ordinarily occurs during head-up tilts was attenuated, such that more blood flowed into the leg. Contrary to expectations, in most animals, venous return was facilitated, such that no more blood accumulated in the hindlimb than when labyrinthine signals were present. These data show that peripheral blood pooling is unlikely to account for the fluctuations in blood pressure that can occur during postural changes of animals lacking inputs from the inner ear. Instead, alterations in total peripheral resistance following vestibular dysfunction could affect the regulation of blood pressure.
大量数据表明，前庭系统有助于血压调节。先前的研究报告称，消除内耳输入的损伤会减弱清醒猫在头向上旋转时后肢通常出现的血管收缩。这些数据引出了一个假设，即内耳功能缺失的动物在头向上姿势改变时会经历相当程度的下体血液淤积。本研究通过比较在去除前庭输入前后，清醒猫从俯卧位进行20至60度头向上倾斜时股动脉和静脉的血流情况，对这一假设进行了测试。在前庭完整的动物中，头向上倾斜开始时后肢的静脉回流大幅下降，在60度旋转开始后5秒，比动物处于俯卧位时低66%。然而，在动物保持头向上姿势15秒后，静脉回流仅比倾斜开始前低33%。在同一时间点，肢体的动脉流入量比基线减少了32%，因此由于重力作用导致的肢体血液流出减少与到达肢体的血液减少精确匹配。在前庭损伤后，头向上倾斜时通常出现的股动脉血流下降减弱，使得更多血液流入腿部。与预期相反，在大多数动物中，静脉回流得到促进，因此后肢积聚的血液并不比存在内耳信号时更多。这些数据表明，外周血液淤积不太可能解释缺乏内耳输入的动物在姿势改变时可能出现的血压波动。相反，前庭功能障碍后总外周阻力的改变可能会影响血压调节。
