Systemic oxygen transport in rats artificially selected for running endurance
Systemic oxygen transport in rats artificially selected for running endurance
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DOI：
10.1016/j.resp.2005.09.012
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发表时间：
2006-04-28
影响因子：
2.3
通讯作者：
Wagner, Peter D.
中科院分区：
文献类型：
--
作者：
Gonzalez, Norberto C.;Howlett, Richard A.;Wagner, Peter D.
遗传和环境影响对个人运动能力的相对贡献很难确定。因此，仔细控制这些影响的动物模型对于理解内在运动能力的决定因素非常有用。对两种不同品系的大鼠进行最大耐力运动时全身O-2运输的研究表明，在第7代，在常规运动中，高容量（HCR）大鼠全身最大O-2摄取（V-O2max）比低容量跑鼠（LCR）高12%。低氧运动时，HCR与LCR之间的V-O2max差异较大。对O-2转运系统相关的O-2电导的分析表明，较高的V-O2max不是由于更高的通气反应、更有效的肺气体交换或血液向组织输送O-2的速率增加。HCR的V-O2max较高的主要原因是组织O-2的提取量增加，这主要是由于组织弥漫性O-2电导较高。在HCR中，组织O-2扩散能力的增强与代表性运动骨骼肌腓肠肌毛细血管密度的增加是平行的。骨骼肌氧化酶、柠檬酸合成酶和P-HAD活性在HCR组高于LCR组。因此，运动过程中观察到的功能特征与骨骼肌中观察到的结构和生化变化是一致的，这意味着肌肉在HCR中摄取和利用O-2的能力增强。结果表明，V-O2max的提高完全是由于肌肉O-2的提取和利用的提高。然而，问题是是否有可能在连续几代的组织水平上保持不断扩大的O-2提取能力，而不同时提高向运动肌肉输送O-2的能力。(c) 2005 Elsevier B.V.版权所有
The relative contribution of genetic and environmental influences to individual exercise capacity is difficult to determine. Accordingly, animal models in which these influences are carefully controlled are highly useful to understand the determinants of intrinsic exercise capacity. Studies of systemic O-2 transport during maximal treadmill exercise in two diverging lines of rats artificially selected for endurance capacity showed that, at generation 7, whole body maximal O-2 uptake (V-O2max) was 12% higher in high capacity (HCR) than in low capacity runners (LCR) during normoxic exercise. The difference in V-O2max between HCR and LCR was larger during hypoxic exercise. Analysis of the linked O-2 conductances of the O-2 transport system showed that the higher V-O2max was not due to a higher ventilatory response, a more effective pulmonary gas exchange, or an increased rate of O-2 delivery to the tissue by blood. The main reason for the higher V-O2max of HCR was an increased tissue O-2 extraction, due largely to a higher tissue diffusive O-2 conductance. The enhanced tissue O-2 diffusing capacity was paralleled by an increased capillary density of a representative locomotory skeletal muscle, the gastrocnemius, in HCR. Activities of skeletal muscle oxidative enzymes citrate synthase and P-HAD were also higher in HCR than LCR. Thus, the functional characteristics observed during exercise are consistent with the structural and biochemical changes observed in skeletal muscle that imply an enhanced capacity for muscle O-2 uptake and utilization in HCR. The results indicate that the improved V-O2max is solely due to enhanced Muscle O-2 extraction and utilization. However, the question arises as to whether it is possible to maintain a continually expanding capacity for O-2 extraction at the tissue level with successive generations, without a parallel improvement in the capacity to deliver O-2 to the exercising muscles. (c) 2005 Elsevier B.V. All rights reserved.