Stainsby W N, Brechue W F, Ameredes B T
Department of Physiology, College of Medicine, University of Florida, Gainesville 32610.
Med Sci Sports Exerc. 1995 Jan;27(1):43-6.
During repetitive contractions, the VO2 of the dog gastrocnemius-plantaris muscle rose with the contraction frequency up to a maximal value and then decreased as contraction frequency was increased further. PVO2 was constant over most of the contraction frequency range. Reducing perfusion pressure/blood flow reduced VO2max with a constant PVO2. During these maneuvers the diffusion conductance, DCO2 (VO2/PVO2), changed with VO2. Raising the perfusion pressure/flow with a pump increased VO2 with a small rise in PVO2 so that DCO2 also increased. Removing tension from the muscle between contractions elevated VO2 and DCO2 without a change in perfusion pressure. Hypoxemia decreased VO2 with a decrease in PVO2; DCO2 remained constant. A three-compartment mathematical model, based on microsphere measurements of regional flow, was used to illustrate how regional flow variations may exist, and how they are poorly revealed in the mixed whole-muscle venous blood. The model shows VO2.g-1 strongly related to flow. As VO2.g-1 increased as Q.g-1 increased, extraction decreased, and DCO2 increased.
在重复性收缩过程中，犬腓肠肌 - 比目鱼肌的耗氧量随收缩频率升高至最大值，然后随着收缩频率进一步增加而降低。在大多数收缩频率范围内，静脉血氧分压保持恒定。降低灌注压力/血流量会在静脉血氧分压恒定的情况下降低最大耗氧量。在这些操作过程中，扩散传导率DCO2（耗氧量/静脉血氧分压）随耗氧量而变化。用泵提高灌注压力/血流量会使耗氧量增加，静脉血氧分压略有升高，因此DCO2也增加。在收缩间隙消除肌肉张力会使耗氧量和DCO2升高，而灌注压力不变。低氧血症会使耗氧量降低，静脉血氧分压也降低；DCO2保持恒定。基于微球测量区域血流量的三室数学模型，用于说明区域血流变化可能如何存在，以及它们在混合的全肌肉静脉血中如何难以显现。该模型显示，每克耗氧量与血流量密切相关。随着每克血流量增加，每克耗氧量增加，提取率降低，DCO2增加。
