Klitzman B, Duling B R
Am J Physiol. 1979 Oct;237(4):H481-90. doi: 10.1152/ajpheart.1979.237.4.H481.
Microvascular hematocrit and its possible relation to oxygen supply were systematically examined. We studied the red cell volume fraction (hematocrit) in arterial blood and in capillaries under a variety of circumstances. Control capillary hematocrit averaged 10.4 +/- 2.0% (SE) and arteriolar (14.2 micrometer ID) hematocrit averaged 13.9 +/- 1.2% in cremaster muscles of pentobarbital-anesthetized hamsters. Carotid artery hematocrit was 53.2 +/- 0.6%. The low microvessel hematocrit could not be entirely explained by a high red cell flux through arteriovenous channels other than capillaries (shunting). Hematocrit was not only low at rest, but varied with physiological stimuli. A 1-Hz muscle contraction increased capillary hematocrit to 18.5 +/- 2.4%, and maximal vasodilation induced a rise to 39.3 +/- 9.5%. The quantitative relations between capillary red cell flux, arterial hematocrit, and total blood flow could be explained by a two-element model of microvascular blood flow that incorporated a relatively slow-moving plasma layer (1.2 micrometer). Such a model would generate a low microvessel hematocrit and might reduce the diffusion capacity of individual capillaries, but would not reduce time-averaged red cell flux or alter steady-state vascular oxygen supply.
对微血管血细胞比容及其与氧气供应的可能关系进行了系统研究。我们在各种情况下研究了动脉血和毛细血管中的红细胞体积分数（血细胞比容）。在戊巴比妥麻醉的仓鼠提睾肌中，对照毛细血管血细胞比容平均为10.4±2.0%（标准误），小动脉（内径14.2微米）血细胞比容平均为13.9±1.2%。颈动脉血细胞比容为53.2±0.6%。微血管血细胞比容低不能完全用通过除毛细血管外的动静脉通道（分流）的高红细胞通量来解释。血细胞比容不仅在静息时低，而且随生理刺激而变化。1赫兹的肌肉收缩使毛细血管血细胞比容增加到18.5±2.4%，最大血管舒张使其升高到39.3±9.5%。毛细血管红细胞通量、动脉血细胞比容和总血流量之间的定量关系可以用一个包含相对缓慢移动的血浆层（1.2微米）的微血管血流二元模型来解释。这样一个模型会产生低微血管血细胞比容，并可能降低单个毛细血管的扩散能力，但不会降低时间平均红细胞通量或改变稳态血管氧气供应。
