Honig C R, Odoroff C L
Am J Physiol. 1981 Feb;240(2):H199-208. doi: 10.1152/ajpheart.1981.240.2.H199.
Probability densities for red cell velocity (V) and capillary length (L) in dog gracilis muscles were computed from mean length and mean velocity assuming two-parameter gamma distributions [Honig, Feldstein, and Frierson, Am. J. Physiol. 233 (Heart Circ. Physiol. 2): H122-H129, 1977]. The distribution of capillary transit times (L/V) was obtained from the ratio of the two gamma distributions. The lower tails of transit time distributions were compared with times thought required for O2 release from capillaries. Results indicate the following. 1) Transit time exceeds O2 release time at rest in all capillaries, regardless of assumptions in the calculation. 2) Transit time appears long enough even in moderate exercise provided mean L is about 1,000 microns and release time is about 100 ms. 3) Capillary recruitment prevents a functional O2 shunt during work at one- to two-thirds maximum O2 uptake (VO2max). 4) Recruitment is insufficient to prevent O2 shunting during exercise to VO2max. 5) Quantitative analysis of O2 transport is severely limited by lack of information about a) microvascular geometry, b) the probability distributions of parameters, and c) the kinetics of O2 release from capillaries.
根据平均长度和平均速度，假设采用双参数伽马分布[霍尼格、费尔德斯坦和弗里尔森，《美国生理学杂志》233卷（心脏循环生理学2）：H122 - H129，1977年]，计算了犬股薄肌中红细胞速度（V）和毛细血管长度（L）的概率密度。毛细血管传输时间（L/V）的分布是通过两个伽马分布的比值得到的。将传输时间分布的下尾与从毛细血管释放氧气所需的时间进行了比较。结果表明如下几点。1）无论计算中的假设如何，所有毛细血管在静息时的传输时间都超过氧气释放时间。2）即使在适度运动中，只要平均L约为1000微米且释放时间约为100毫秒，传输时间似乎也足够长。3）在以最大摄氧量（VO2max）的三分之一到三分之二进行工作期间，毛细血管募集可防止功能性氧气分流。4）在运动至VO2max期间，募集不足以防止氧气分流。5）由于缺乏以下信息，氧气运输的定量分析受到严重限制：a）微血管几何形状，b）参数的概率分布，以及c）毛细血管中氧气释放的动力学。
