Flamm S D, Taki J, Moore R, Lewis S F, Keech F, Maltais F, Ahmad M, Callahan R, Dragotakes S, Alpert N
Department of Radiology, Massachusetts General Hospital, Boston, MA.
Circulation. 1990 May;81(5):1550-9. doi: 10.1161/01.cir.81.5.1550.
To determine the effect of relative exercise intensity on organ blood volume and its relation to cardiac function, changes in relative blood volume and cardiac function were monitored with radionuclide techniques in 14 healthy volunteers. After labeling the subject's red cells with technetium 99m, we acquired data at rest, zero-load cycling, and at 50%, 75%, and 100% of maximal oxygen uptake. From rest to zero-load cycling, leg blood volume decreased 32 +/- 2% (mean +/- SEM), whereas relative end-diastolic blood volume increased 9.6 +/- 1.2%, and lung blood volume increased 18 +/- 2%, suggesting that the lungs may act as a blood volume buffer during periods of acutely increased venous return. With relative increasing exercise, leg blood volume stabilized, and then the blood volume in the abdominal organs decreased, further augmenting cardiopulmonary blood volume; leg blood volume and abdominal blood volume decreased by 23 +/- 2% and 19 +/- 2% from baseline, respectively, whereas thoracic blood volume increased 38 +/- 4%. In the abdomen, large decreases in blood volume were observed in the spleen (46 +/- 2%), kidney (24 +/- 4%), and liver (18 +/- 4%). In contrast, lung blood volume increased 50 +/- 4%, with the upper lung fields increasing more than the lower. Blood sampling revealed an increase in the hematocrit level by 4.3 +/- 0.4 units at peak exercise that paralleled the decrease in splenic blood volume (r2 = -0.64, p less than 0.001), suggesting a role for the spleen in augmenting cardiovascular performance by the release of concentrated red blood cells into general circulation. We conclude that upright exercise results in marked blood volume shifts from the legs and abdominal organs to the heart and lungs in a dynamic process correlating closely with oxygen consumption.
为了确定相对运动强度对器官血容量的影响及其与心脏功能的关系，我们采用放射性核素技术对14名健康志愿者的相对血容量和心脏功能变化进行了监测。在用99m锝标记受试者的红细胞后，我们在静息状态、零负荷骑行以及最大摄氧量的50%、75%和100%时采集了数据。从静息状态到零负荷骑行，腿部血容量减少了32±2%（平均值±标准误），而相对舒张末期血容量增加了9.6±1.2%，肺血容量增加了18±2%，这表明在静脉回流急性增加期间，肺部可能起到血容量缓冲的作用。随着相对运动强度的增加，腿部血容量趋于稳定，然后腹部器官的血容量减少，进一步增加了心肺血容量；腿部血容量和腹部血容量分别比基线水平降低了23±2%和19±2%，而胸部血容量增加了38±4%。在腹部，脾脏（46±2%）、肾脏（24±4%）和肝脏（18±4%）的血容量出现大幅下降。相比之下，肺血容量增加了50±4%，上肺野的增加幅度大于下肺野。血液采样显示，运动峰值时血细胞比容水平增加了4.3±0.4个单位，这与脾脏血容量的减少平行（r2 = -0.64，p<0.001），表明脾脏通过将浓缩的红细胞释放到体循环中，在增强心血管功能方面发挥了作用。我们得出结论，直立运动会导致血容量在动态过程中从腿部和腹部器官显著转移至心脏和肺部，且这一过程与耗氧量密切相关。
