Ogoh Shigehiko, Fisher James P, Purkayastha Sushmita, Dawson Ellen A, Fadel Paul J, White Michael J, Zhang Rong, Secher Niels H, Raven Peter B
Dept. of Integrative Physiology, Univ. of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107, USA.
J Appl Physiol (1985). 2007 Feb;102(2):713-21. doi: 10.1152/japplphysiol.00801.2006. Epub 2006 Oct 26.
We sought to examine the regulation of cerebral blood flow during 10 min of recovery from mild, moderate, and heavy cycling exercise by measuring middle cerebral artery blood velocity (MCA V). Transfer function analyses between changes in arterial blood pressure and MCA V were used to assess the frequency components of dynamic cerebral autoregulation (CA). After mild and moderate exercise, the decreases in mean arterial pressure (MAP) and mean MCA V (MCA Vm) were small. However, following heavy exercise, MAP was rapidly and markedly reduced, whereas MCA Vm decreased slowly (-23 +/- 4 mmHg and -4 +/- 1 cm/s after 1 min for MAP and MCA Vm, respectively; means +/- SE). Importantly, for each workload, the normalized low-frequency transfer function gain between MAP and MCA Vm remained unchanged from rest to exercise and during recovery, indicating a maintained dynamic CA. Similar results were found for the systolic blood pressure and systolic MCA V relationship. In contrast, the normalized low-frequency transfer function gain between diastolic blood pressure and diastolic MCA V (MCA Vd) increased from rest to exercise and remained elevated in the recovery period (P < 0.05). However, MCA Vd was quite stable on the cessation of exercise. These findings suggest that MCA V is well maintained following mild to heavy dynamic exercise. However, the increased transfer function gain between diastolic blood pressure and MCA Vd suggests that dynamic CA becomes less effective in response to rapid decreases in blood pressure during the initial 10 min of recovery from dynamic exercise.
我们试图通过测量大脑中动脉血流速度（MCA V），来研究在从轻度、中度和重度骑行运动恢复的10分钟内脑血流量的调节情况。利用动脉血压变化与MCA V之间的传递函数分析，来评估动态脑自动调节（CA）的频率成分。轻度和中度运动后，平均动脉压（MAP）和平均MCA V（MCA Vm）的下降幅度较小。然而，在重度运动后，MAP迅速且显著降低，而MCA Vm下降缓慢（1分钟后，MAP和MCA Vm分别为-23±4 mmHg和-4±1 cm/s；均值±标准误）。重要的是，对于每个工作量，从静息到运动以及恢复期间，MAP与MCA Vm之间的标准化低频传递函数增益保持不变，表明动态CA得以维持。收缩压与收缩期MCA V关系也得到了类似结果。相比之下，舒张压与舒张期MCA V（MCA Vd）之间的标准化低频传递函数增益从静息到运动时增加，并在恢复期保持升高（P<0.05）。然而，运动停止后MCA Vd相当稳定。这些发现表明，轻度至重度动态运动后MCA V能得到良好维持。然而，舒张压与MCA Vd之间传递函数增益的增加表明，在动态运动恢复的最初10分钟内，动态CA对血压快速下降的反应变得不那么有效。
