Kayar S R, Banchero N
Department of Physiology, University of Colorado School of Medicine, Denver 80262.
Respir Physiol. 1987 Dec;70(3):275-86. doi: 10.1016/0034-5687(87)90010-7.
The volume density and distribution of mitochondria relative to capillaries have been measured using the technique of point counting in concentric rings, on normal and hypertrophied guinea pig myocardium. Right ventricular hypertrophy was produced by hypobaric hypoxia. In control guinea pigs right ventricular weight increased linearly with body weight. In control and hypoxic guinea pigs fiber cross sectional area (FCSA) and ventricular weight were related by a single straight line. Capillary density decreased hyperbolically with FCSA in both control and hypoxic animals. Capillary density was significantly higher (P less than 0.001) in the right ventricles of the hypoxic animals than in controls when the fibers were small but this difference disappeared as the fibers hypertrophied beyond FCSA values of 260 microns2. Volume density of mitochondria reached a peak (29-35%) close to the capillary but then decreased significantly in the spaces farthest from the capillary (mean 25.2%). There was no significant difference in peak mitochondrial volume density in controls versus hypoxic animals. There was thus an increase in the total volume of mitochondria in these myofibers that was in direct proportion to the increases in FCSA and heart volume. The highest volume density of mitochondria was found at a distance that is approximately 15% of the total distance over which O2 must diffuse in myocardial tissue and the peak volume density of mitochondria was thus a function of capillary density. The speculation is presented that the distribution of mitochondria may be related both to oxygen supply to the mitochondria and to the movement of high energy phosphate compounds out of mitochondria for use by myofibrils.
运用同心环上的点计数技术，已对正常和肥大豚鼠心肌中线粒体相对于毛细血管的体积密度及分布进行了测量。低压缺氧导致右心室肥大。在对照豚鼠中，右心室重量随体重呈线性增加。在对照和缺氧豚鼠中，纤维横截面积（FCSA）与心室重量由一条直线相关联。在对照和缺氧动物中，毛细血管密度均随FCSA呈双曲线下降。当纤维较小时，缺氧动物右心室的毛细血管密度显著高于对照组（P小于0.001），但当纤维肥大超过260平方微米的FCSA值时，这种差异消失。线粒体体积密度在靠近毛细血管处达到峰值（29 - 35%），但在距离毛细血管最远的区域则显著下降（平均25.2%）。对照动物与缺氧动物的线粒体体积密度峰值无显著差异。因此，这些肌纤维中线粒体的总体积增加，且与FCSA和心脏体积的增加成正比。线粒体体积密度最高值出现在距氧气在心肌组织中扩散总距离约15%处，因此线粒体的峰值体积密度是毛细血管密度的函数。有人推测，线粒体的分布可能既与线粒体的氧气供应有关，也与高能磷酸化合物从线粒体中运出供肌原纤维使用有关。
