Honig C R, Feldstein M L, Frierson J L
Am J Physiol. 1977 Jul;233(1):H122-9. doi: 10.1152/ajpheart.1977.233.1.H122.
Total capillary length, capillary segment length, and number of anastomoses per capillary were measured in rat gracilis muscle at rest and after 2 min of phasic contraction. Mean values of the foregoing variables at rest (+/-SD) were, respectively, 1,012 micronm +/- 484, 409 micron +/- 274, and 0.83 +/- 1.09. Total capillary lengths are well described by the gamma distribution, number of anastomoses by the negative binomial distribution, and segment length by the Weibull distribution. Contraction has no significant effect on the means or the frequency distributions, indicating that: 1) pressure gradients between adjacent capillaries are small, and 2) intercapillary anastomoses do not improve flow distribution in exercise. Erythrocyte velocities observed in resting muscle (Burton, K. S., and P. C. Johnson. Am J. Physiol. 223: 517-524, 1972) were shown to be adequately characterized by the gamma distribution. From these velocities and the observed distribution of path lengths, we computed an estimated distribution of capillary transit times. Mean transit time was 4.29 s. The median was 2.45 s, and 11% of values exceeded 8 s. The range was 90 ms-43 s. This heterogeneity of transit times should profoundly affect calculations of O2 transport and the shape of indicator dilution curves.
在大鼠股薄肌处于静息状态以及进行2分钟的阶段性收缩后，测量了毛细血管总长度、毛细血管段长度以及每条毛细血管的吻合支数量。上述变量在静息状态下的平均值（±标准差）分别为1012微米±484、409微米±274以及0.83±1.09。毛细血管总长度可用伽马分布很好地描述，吻合支数量可用负二项分布描述，段长度可用威布尔分布描述。收缩对平均值或频率分布没有显著影响，这表明：1）相邻毛细血管之间的压力梯度较小，2）毛细血管间的吻合支并不能改善运动时的血流分布。在静息肌肉中观察到的红细胞速度（Burton, K. S., and P. C. Johnson. Am J. Physiol. 223: 517 - 524, 1972）已被证明可用伽马分布充分表征。根据这些速度以及观察到的路径长度分布，我们计算了毛细血管通过时间的估计分布。平均通过时间为4.29秒。中位数为2.45秒，11%的值超过8秒。范围为90毫秒至43秒。这种通过时间的异质性应会深刻影响氧气运输的计算以及指示剂稀释曲线的形状。
