Anatomic capillarization is maintained in relative excess of fiber oxidative capacity in some skeletal muscles of late middle-aged rats
Anatomic capillarization is maintained in relative excess of fiber oxidative capacity in some skeletal muscles of late middle-aged rats
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DOI：
10.1152/japplphysiol.01309.2003
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发表时间：
2004-06-01
影响因子：
3.3
通讯作者：
Vogell, JE
中科院分区：
文献类型：
--
作者：
Hepple, RT;Vogell, JE
毛细血管与纤维 (C/F) 界面的解剖尺寸通过确定可用于扩散的表面积，在从血液到组织的 O-2 通量中发挥着重要作用，并且在各种肌肉有氧能力中保持与纤维线粒体体积的相对比例。在本研究中，我们检查了对不同骨骼肌或肌肉区域中 C/F 界面解剖尺寸的估计（个体 C/F 比与纤维周长的商，C/F 周长交换 (CFPE) 指数）和纤维氧化能力，以检验以下假设：在老化肌肉中，毛细血管化将保持相对过量的纤维氧化能力降低。切除年轻成年（8个月大）和中年晚期（28-30个月大）Fischer 344 x Brown挪威F1杂交大鼠的右侧腓肠肌、跖肌和比目鱼肌，用于评估通过电子传递链复合物I-III的通量和/或毛细血管化的形态测量估计。老年动物的腓肠肌的肌肉质量较低（青年组为 2,076+/-32 毫克，中年后期为 1,825+/-47 毫克；平均值+/-SE），但跖肌或比目鱼肌则不然。年老动物腓肠肌白色区域的纤维较小，但腓肠肌红色区域的纤维较大。对于任何肌肉/区域，纤维周围的毛细血管数量、个体 C/F 比或组间 CFPE 指数没有差异，而在中年晚期动物中，通过复合物 I-III 的通量减少了 29-43%。因此，比目鱼肌和腓肠肌白色区域的解剖毛细血管指数（个体C/F比或CFPE指数）与纤维氧化能力的商较大，但老年动物的腓肠肌红色区域则不然，这表明中年晚期大鼠的某些肌肉区域的解剖毛细血管维持在相对过量的氧化能力。
The anatomic size of the capillary-to-fiber (C/F) interface plays an important role in O-2 flux from blood to tissue by determining the surface area available for diffusion and is maintained in relative proportion to fiber mitochondrial volume across a wide range of muscle aerobic capacity. In the present study, we examined an estimate of the anatomic size of the C/F interface [the quotient of the individual C/F ratio and fiber perimeter, C/F perimeter exchange (CFPE) index] and fiber oxidative capacity in different skeletal muscles, or muscle regions, to test the hypothesis that capillarization would be maintained in relative excess of reduced fiber oxidative capacity in aged muscles. The right gastrocnemius, plantaris, and soleus muscles from young adult (8 mo old) and late middle-aged (28-30 mo old) Fischer 344 x Brown Norway F1 hybrid rats were excised for evaluation of flux through electron transport chain complexes I-III and/or morphometric estimation of capillarization. Muscle mass was lower in the gastrocnemius muscles of the older animals (2,076+/-32 vs. 1,825+/-47 mg in young adult vs. late middle-aged, respectively; mean+/-SE) but not the plantaris or soleus muscles. Fibers were smaller in the white region of gastrocnemius muscles but larger in the red region of gastrocnemius muscles of the older animals. There was no difference in the number of capillaries around a fiber, the individual C/F ratio, or the CFPE index between groups for any muscle/region, whereas flux through complexes I-III was reduced by 29-43% in late middle-aged animals. Thus the greater quotient of indexes of anatomic capillarity (individual C/F ratio or CFPE index) and fiber oxidative capacity in soleus and the white region of gastrocnemius muscles, but not in the red region of gastrocnemius muscles of the older animals, shows that anatomic capillarity is maintained in relative excess of oxidative capacity in some muscle regions in late middle-aged rats.