Stringer W, Wasserman K, Casaburi R, Pórszász J, Maehara K, French W
Division of Respiratory and Critical Care Physiology and Medicine, Harbor-University of California, Los Angeles Medical Center, Torrance 90509.
J Appl Physiol (1985). 1994 Apr;76(4):1462-7. doi: 10.1152/jappl.1994.76.4.1462.
The slow rise in O2 uptake (VO2), which has been shown to be linearly correlated with the increase in lactate concentration during heavy constant work rate exercise, led us to investigate the role of H+ from lactic acid in facilitating oxyhemoglobin (O2Hb) dissociation. We measured femoral venous PO2, O2Hb saturation, pH, PCO2, lactate, and standard HCO3- during increasing work rate and two constant work rate cycle ergometer exercise tests [below and above the lactic acidosis threshold (LAT)] in two groups of five healthy subjects. Mean end-exercise femoral vein blood and VO2 values for the below- and above-LAT square waves and the increasing work rate protocol were, respectively, PO2 of 19.8 +/- 2.1 (SD), 18.8 +/- 4.7, and 19.8 +/- 3.3 Torr; O2 saturation of 22.5 +/- 4.1, 13.8 +/- 4.2, and 18.5 +/- 6.3%; pH of 7.26 +/- 0.01, 7.02 +/- 0.11, and 7.09 +/- 0.07; lactate of 1.9 +/- 0.9, 11.0 +/- 3.8, and 8.3 +/- 2.9 mmol/l; and VO2 of 1.77 +/- 0.24, 3.36 +/- 0.4, and 3.91 +/- 0.68 l/min. End-exercise femoral vein PO2 did not differ statistically for the three protocols, whereas O2Hb saturation continued to decrease for work rates above LAT. We conclude that decreasing capillary PO2 accounted for most of the O2Hb dissociation during below-LAT exercise and that acidification of muscle capillary blood due to lactic acidosis accounted for virtually all of the O2Hb dissociation above LAT.
在重度恒负荷运动期间，氧气摄取量（VO₂）的缓慢上升已被证明与乳酸浓度的增加呈线性相关，这促使我们研究乳酸中的H⁺在促进氧合血红蛋白（O₂Hb）解离中的作用。我们在两组各五名健康受试者中，于运动强度增加以及两次恒负荷周期测力计运动测试（低于和高于乳酸酸中毒阈值（LAT））期间，测量了股静脉血氧分压（PO₂）、O₂Hb饱和度、pH值、二氧化碳分压（PCO₂）、乳酸和标准碳酸氢根（HCO₃⁻）。低于LAT和高于LAT的方波以及运动强度增加方案的平均运动结束时股静脉血和VO₂值分别为：PO₂为19.8±2.1（标准差）、18.8±4.7和19.8±3.3托；O₂饱和度为22.5±4.1、13.8±4.2和18.5±6.3%；pH值为7.26±0.01、7.02±0.11和7.09±0.07；乳酸为1.9±0.9、11.0±3.8和8.3±2.9毫摩尔/升；VO₂为1.77±0.24、3.36±0.4和3.91±0.68升/分钟。三种方案的运动结束时股静脉PO₂在统计学上无差异，而高于LAT的运动强度下O₂Hb饱和度持续下降。我们得出结论，在低于LAT的运动中，毛细血管PO₂的降低是O₂Hb解离的主要原因，而乳酸酸中毒导致的肌肉毛细血管血液酸化几乎是高于LAT时所有O₂Hb解离的原因。
