Phenotype of capillaries in skeletal muscle of nNOS-knockout mice
Phenotype of capillaries in skeletal muscle of nNOS-knockout mice
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DOI：
10.1152/ajpregu.00434.2012
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发表时间：
2013-06-01
影响因子：
2.8
通讯作者：
Hoppeler, Hans
中科院分区：
文献类型：
--
作者：
Baum, Oliver;Vieregge, Max;Hoppeler, Hans
由于神经元型一氧化氮合酶（nNOS）对骨骼肌中的小动脉血流具有众所周知的影响，我们比较了雄性nNOS敲除（KO）小鼠和野生型（WT）同窝仔趾长伸肌（EDL）肌肉中随后毛细血管的超微结构和血流动力学。毛细血管-纤维（C/F）比（-9.1%）较低（P 0.05）。形态计量学估计的毛细血管所占面积以及亚细胞区室的体积和表面密度在两个菌株之间差异不显著（P > 0.05）。活体显微镜检查显示，两种品系之间的毛细血管直径（nNOS-KO小鼠与WT小鼠相比为+3%）和EDL肌肉中红细胞的平均速度（nNOS-KO小鼠与WT小鼠相比为+25%）均无显著差异（P > 0.05）。计算的毛细血管剪切应力也无显著差异（nNOS-KO小鼠为3.8 +/- 2.2 dyn/cm 2，WT小鼠为2.1 +/- 2.2 dyn/cm 2; P > 0.05）。nNOS-KO小鼠的EDL肌肉中血管内皮生长因子（VEGF）-A的mRNA水平低于WT同窝小鼠（-37%; P 0.05）。我们的研究结果支持这样的论点，即VEGF-A mRNA的表达和C/F比，而不是超微结构或血流动力学的/在骨骼肌毛细血管在基础条件下取决于nNOS的表达。
Because neuronal nitric oxide synthase (nNOS) has a well-known impact on arteriolar blood flow in skeletal muscle, we compared the ultrastructure and the hemodynamics of/in the ensuing capillaries in the extensor digitorum longus (EDL) muscle of male nNOS-knockout (KO) mice and wild-type (WT) littermates. The capillary-to-fiber (C/F) ratio (-9.1%) was lower (P 0.05). Morphometrical estimation of the area occupied by the capillaries as well as the volume and surface densities of the subcellular compartments differed nonsignificantly (P > 0.05) between the two strains. Intravital microscopy revealed neither the capillary diameter (+3% in nNOS-KO mice vs. WT mice) nor the mean velocity of red blood cells in EDL muscle (+25% in nNOS-KO mice vs. WT mice) to significantly vary (P > 0.05) between the two strains. The calculated shear stress in the capillaries was likewise nonsignificantly different (3.8 +/- 2.2 dyn/cm(2) in nNOS-KO mice and 2.1 +/- 2.2 dyn/cm2 in WT mice; P > 0.05). The mRNA levels of vascular endothelial growth factor (VEGF)-A were lower in the EDL muscle of nNOS-KO mice than in the WT littermates (-37%; P 0.05). Our findings support the contention that VEGF-A mRNA expression and C/F-ratio but not the ultrastructure or the hemodynamics of/in capillaries in skeletal muscle at basal conditions depend on the expression of nNOS.