Suzuki J, Gao M, Ohinata H, Kuroshima A, Koyama T
Laboratory of Sports Physiology, Research and Education Center for Winter Sports, Hokkaido University of Education, Sapporo, 002 Japan.
Jpn J Physiol. 1997 Dec;47(6):513-20. doi: 10.2170/jjphysiol.47.513.
The effects of 4-week cold exposure on capillary geometry, particularly in terms of the distribution of arteriolar and venular capillaries and their capillary domain areas, were studied for different types of skeletal muscles in male Wistar rats. Morphological data for capillaries and muscles were obtained from muscle cross-sections exposed to a double-staining method that distinguishes arteriolar portions from venular portions of capillaries. In soleus (SOL; type I fibers) and the deep portion of gastrocnemius (GASd; type I and IIa fibers) muscles, total capillary density and density of arteriolar capillary were significantly greater in cold-acclimated (CA) rats than in warm control (WC) rats (p < 0.05). In the superficial portion of the gastrocnemius (GASs; type IIb fibers), however, these changes in capillarity were not observed. After cold acclimation, fiber cross-sectional area was significantly decreased by 21, 28 and 15% in SOL, GASd and GASs (p < 0.05), respectively. In SOL and GASd but not in GASs, capillary domain areas of arteriolar, intermediate and venular portions in CA were significantly smaller than those of the respective portions in WC (p < 0.05). Succinate dehydrogenase activity was significantly increased after cold acclimation, by 31% in SOL and 21% in GASd (p < 0.05). In GASs, however, the activity remained unchanged after cold acclimation. These results suggest that adaptive changes in the oxygen transport system were observed after cold acclimation in the skeletal muscles that are mainly composed of oxidative fibers. These adaptive changes may improve the effective oxygen supply to muscle tissues that contribute to thermogenesis in a cold atmosphere.
研究了4周冷暴露对雄性Wistar大鼠不同类型骨骼肌毛细血管几何形态的影响，特别是小动脉毛细血管和小静脉毛细血管的分布及其毛细血管领域面积。毛细血管和肌肉的形态学数据来自于采用双染色法处理的肌肉横截面，该方法可区分毛细血管的小动脉部分和小静脉部分。在比目鱼肌（SOL；I型纤维）和腓肠肌深部（GASd；I型和IIa型纤维）中，冷适应（CA）大鼠的总毛细血管密度和小动脉毛细血管密度显著高于温暖对照组（WC）大鼠（p < 0.05）。然而，在腓肠肌浅部（GASs；IIb型纤维）中，未观察到毛细血管的这些变化。冷适应后，SOL、GASd和GASs的纤维横截面积分别显著减少了21%、28%和15%（p < 0.05）。在SOL和GASd中，而非GASs中，CA组小动脉、中间和小静脉部分的毛细血管领域面积显著小于WC组相应部分（p < 0.05）。冷适应后，琥珀酸脱氢酶活性显著增加，SOL中增加了31%，GASd中增加了21%（p < 0.05）。然而，在GASs中，冷适应后活性保持不变。这些结果表明，在主要由氧化纤维组成的骨骼肌中，冷适应后观察到了氧运输系统的适应性变化。这些适应性变化可能会改善向肌肉组织的有效氧气供应，从而有助于在寒冷环境中产生热量。
