Mathieu-Costello O, Hoppeler H, Weibel E R
Department of Medicine, University of California, San Diego, La Jolla 92093-0623.
J Appl Physiol (1985). 1989 Mar;66(3):1436-42. doi: 10.1152/jappl.1989.66.3.1436.
Capillary orientation (anisotropy) was compared in hindlimb muscles of mammals of different size and/or different aerobic capacity (dog, goat, pony, and calf). All muscles were fixed by vascular perfusion at sarcomere lengths ranging from 1.5 to 2.7 micron. The ratios of capillary counts per fiber cross-sectional area on two sets of sections (0 and 90 degrees) to the muscle fiber axis were used to estimate capillary anisotropy and the coefficient c(K,0) relating 1) capillary counts on transverse sections (a commonly used parameter to assess muscle capillarity) and 2) capillary length per volume of fiber (i.e., capillary length density). Capillary orientation parallel to the muscle fiber axis decreased substantially with muscle fiber shortening. In muscles fixed at sarcomere lengths of 2.69 microns (dog vastus intermedius) and 1.52 microns (dog gastrocnemius), capillary tortuosity and branching added 7 and 64%, respectively, to capillary length density. The data obtained in this study are highly consistent with the previously demonstrated relationship between capillary anisotropy and sarcomere length in extended vs. contracted rat muscles, by use of the same method. Capillary anisotropy in mammalian locomotory muscles is curvilinearly related to sarcomere length. No systematic difference was found in capillary tortuosity with either body size, athletic ability, or aerobic capacity. Capillary tortuosity is a consequence of fiber shortening rather than an indicator of the O2 requirements of the tissue.
比较了不同大小和/或不同有氧能力的哺乳动物（狗、山羊、小马和小牛）后肢肌肉中的毛细血管取向（各向异性）。所有肌肉均通过血管灌注固定，肌节长度范围为1.5至2.7微米。两组与肌纤维轴呈0度和90度的切片上每纤维横截面积的毛细血管计数比率，用于估计毛细血管各向异性以及系数c(K,0)，该系数关联1）横截面上的毛细血管计数（评估肌肉毛细血管化的常用参数）和2）每纤维体积的毛细血管长度（即毛细血管长度密度）。与肌纤维轴平行的毛细血管取向随肌纤维缩短而大幅降低。在肌节长度固定为2.69微米（狗股中间肌）和1.52微米（狗腓肠肌）的肌肉中，毛细血管的曲折度和分支分别使毛细血管长度密度增加了7%和64%。本研究获得的数据与先前通过相同方法证明的伸展与收缩大鼠肌肉中毛细血管各向异性与肌节长度之间的关系高度一致。哺乳动物运动肌肉中的毛细血管各向异性与肌节长度呈曲线相关。在毛细血管曲折度方面，未发现与体型、运动能力或有氧能力存在系统性差异。毛细血管曲折度是纤维缩短的结果，而非组织氧气需求的指标。
