Medical Clinic VII, Sports Medicine, University of Heidelberg, Germany.
Compr Physiol. 2012 Apr;2(2):1463-89. doi: 10.1002/cphy.c080113.
Hemoglobin (Hb) constitutes a vital link between ambient O2 availability and aerobic metabolism by transporting oxygen (O2) from the respiratory surfaces of the lungs or gills to the O2-consuming tissues. The amount of O2 available to tissues depends on the blood-perfusion rate, as well as the arterio-venous difference in blood O2 contents, which is determined by the respective loading and unloading O2 tensions and Hb-O2-affinity. Short-term adjustments in tissue oxygen delivery in response to decreased O2 supply or increased O2 demand (under exercise, hypoxia at high altitude, cardiovascular disease, and ischemia) are mediated by metabolically induced changes in the red cell levels of allosteric effectors such as protons (H(+)), carbon dioxide (CO2), organic phosphates, and chloride (Cl(-)) that modulate Hb-O2 affinity. The long-term, genetically coded adaptations in oxygen transport encountered in animals that permanently are subjected to low environmental O2 tensions commonly result from changes in the molecular structure of Hb, notably amino acid exchanges that alter Hb's intrinsic O2 affinity or its sensitivity to allosteric effectors. Structure-function studies of animal Hbs and human Hb mutants illustrate the different strategies for adjusting Hb-O2 affinity and optimizing tissue oxygen supply.
血红蛋白（Hb）在运输氧气（O2）方面起着至关重要的作用，它将氧气从肺部或鳃的呼吸表面输送到需要氧气的组织中，从而使周围氧气的可用性与需氧代谢相连接。组织中可用的氧气量取决于血液灌注率以及血液中氧气含量的动静脉差异，这由各自的加载和卸载氧气张力以及血红蛋白-氧气亲和力决定。为了应对氧气供应减少或氧气需求增加（在运动、高海拔缺氧、心血管疾病和缺血期间），组织氧气输送的短期调节是通过代谢诱导的变构效应物（如质子（H(+））、二氧化碳（CO2）、有机磷酸盐和氯离子（Cl(-)））在红细胞水平上的变化来介导的，这些变化调节血红蛋白-氧气亲和力。在长期内，动物对低环境氧气张力的遗传编码适应性通常是由于血红蛋白分子结构的变化引起的，特别是氨基酸交换改变了血红蛋白的内在氧气亲和力或对变构效应物的敏感性。动物 Hbs 和人类 Hb 突变体的结构功能研究说明了调节血红蛋白-氧气亲和力和优化组织氧气供应的不同策略。
