Rogers H B, Schroeder T, Secher N H, Mitchell J H
Department of Anesthesia, Rigshospitalet, University of Copenhagen, Denmark.
J Appl Physiol (1985). 1990 Jun;68(6):2358-61. doi: 10.1152/jappl.1990.68.6.2358.
Cerebral blood flow (CBF) was determined in humans at rest and during four consecutive unilateral static contractions of the knee extensors. Each contraction was maintained for 3 min 15 s with the subjects in a semisupine position. The contractions corresponded to 8, 16, 24, and 32% of the maximal voluntary contraction (MVC) and utilized alternate legs. CBF (measured by the 133Xe clearance technique) was expressed by a noncompartmental flow index (ISI). Heart rate and mean arterial pressure increased from resting values of 73 (55-80) beats/min and 88 (74-104) mmHg to 106 (86-138) beats/min and 124 (102-146) mmHg, respectively (P less than 0.0005), during the contraction at 32% MVC. Arterial PCO2 and central venous pressure did not change. Corrected to the average resting PCO2, CBF during control was 55 (35-73) ml.100 g-1.min-1 and remained constant during contractions. Cerebral vascular resistance increased from 1.5 (1.0-2.2) to 2.4 (1.4-3.0) mmHg. 100 g.min.ml-1 (P less than 0.025) at 32% of MVC. There was no difference in CBF between the two hemispheres at rest or during exercise. In contrast to dynamic leg exercise, static leg exercise is not associated with an increase in global CBF when measured by the 133Xe clearance technique.
在人体处于静息状态以及连续进行四次单侧膝关节伸肌静态收缩期间，测定了脑血流量（CBF）。每次收缩持续3分15秒，受试者处于半仰卧位。收缩强度分别对应最大自主收缩（MVC）的8%、16%、24%和32%，且两腿交替进行。CBF（通过133Xe清除技术测量）用非房室血流指数（ISI）表示。在32%MVC的收缩过程中，心率和平均动脉压分别从静息值73（55 - 80）次/分钟和88（74 - 104）mmHg升高至106（86 - 138）次/分钟和124（102 - 146）mmHg（P < 0.0005）。动脉血二氧化碳分压和中心静脉压未发生变化。校正至平均静息二氧化碳分压后，对照期间的CBF为55（35 - 73）ml·100g-1·min-1，在收缩过程中保持恒定。脑血管阻力从1.5（1.0 - 2.2）mmHg·100g·min·ml-1升高至2.4（1.4 - 3.0）mmHg·100g·min·ml-1（在32%MVC时，P < 0.025）。静息或运动期间，两个半球的CBF无差异。与动态腿部运动不同，当通过133Xe清除技术测量时，静态腿部运动不会使全脑CBF增加。
