Baum Oliver, Sollberger Carole, Raaflaub Andrea, Odriozola Adolfo, Spohr Gunnar, Frese Sebastian, Tschanz Stefan A
Institute of Physiology, Charité-Universitätsmedizin Berlin, D-10117 Berlin, Germany
Institute of Anatomy, University of Bern, CH-3012 Bern, Switzerland.
J Exp Biol. 2018 Feb 19;221(Pt 4):jeb171819. doi: 10.1242/jeb.171819.
To work out which microvascular remodeling processes occur in murine skeletal muscle during endurance exercise, we subjected C57BL/6 mice to voluntary running wheel training for 1 week (1 wk-t) or 6 weeks (6 wks-t). By means of morphometry, the capillarity as well as the compartmental and sub-compartmental structure of the capillaries were quantitatively described at the light microscopy level and at the electron microscopy level, respectively, in the plantaris (PLNT) muscle of the exercising mice in comparison to untrained littermates. In the early phase of the training (1 wk-t), angiogenesis [32% higher capillary/fiber (C/F) ratio; <0.05] in PLNT muscle was accompanied by a tendency for capillary lumen enlargement (30%; 0.06) and a reduction of the pericapillary basement membrane thickness [(CBMT) 12.7%; 0.09] as well as a 21% shortening of intraluminal protrusion length (<0.05), all compared with controls. After long-term training (6 wks-t), when the mice reached a steady state in running activity, additional angiogenesis (C/F ratio: 76%; <0.05) and a 16.3% increase in capillary tortuosity (<0.05) were established, accompanied by reversal of the lumen expansion (23%; >0.05), further reduction of the CBMT (16.5%; <0.05) and additional shortening of the intraluminal protrusion length (23%; <0.05), all compared with controls. Other structural indicators, such as capillary profile sizes, profile area densities, perimeters of the capillary compartments and concentrations of endothelium-pericyte peg-socket junctions, were not significantly different between the mouse groups. Besides angiogenesis, increase of capillary tortuosity and reduction of CBMT represent the most striking microvascular remodeling processes in skeletal muscle of mice that undergo running wheel training.
为了确定耐力运动期间小鼠骨骼肌中发生哪些微血管重塑过程，我们对C57BL/6小鼠进行了1周（1wk-t）或6周（6wks-t）的自愿跑轮训练。通过形态测量法，分别在光学显微镜水平和电子显微镜水平上，对运动小鼠比目鱼肌（PLNT）中毛细血管密度以及毛细血管的分区和亚分区结构进行了定量描述，并与未训练的同窝小鼠进行比较。在训练的早期阶段（1wk-t），与对照组相比，比目鱼肌中的血管生成（毛细血管/纤维（C/F）比高32%；<0.05）伴随着毛细血管腔扩大的趋势（30%；0.06）、毛细血管周基底膜厚度（CBMT）降低（12.7%；0.09）以及管腔内突出长度缩短21%（<0.05）。长期训练（6wks-t）后，当小鼠的跑步活动达到稳定状态时，出现了额外的血管生成（C/F比：76%；<0.05）和毛细血管迂曲度增加16.3%（<0.05），同时伴随着管腔扩张的逆转（23%；>0.05）、CBMT进一步降低（16.5%；<0.05）以及管腔内突出长度进一步缩短（23%；<0.05），所有这些均与对照组相比。其他结构指标，如毛细血管轮廓大小、轮廓面积密度、毛细血管分区周长以及内皮-周细胞栓-窝连接浓度，在小鼠组之间没有显著差异。除了血管生成外，毛细血管迂曲度增加和CBMT降低是接受跑轮训练的小鼠骨骼肌中最显著的微血管重塑过程。
