Honig C R, Frierson J L, Gayeski T E
Department of Physiology, School of Medicine and Dentistry, University of Rochester, New York 14642.
Am J Physiol. 1989 Feb;256(2 Pt 2):H375-82. doi: 10.1152/ajpheart.1989.256.2.H375.
Calculations indicate that the PO2 in plasma falls to zero approximately 3 microns from an erythrocyte at O2 consumption (VO2) characteristic of myocardium (Federspiel, W.A., and A. Popel, Microvasc. Res. 32: 164-189, 1986). We measured distances between individual red cells along capillaries in rat hearts rapidly frozen in situ. Cell spacing varied widely even in branches of the same capillary. Plasma gaps between red cells were divided into two populations, those less than 5 microns and those greater than 5 microns. Mean gap lengths were 2.1 and 16.5 microns, respectively. Although the number of long plasma gaps was underestimated, gaps greater than 5 microns accounted for one-third of observed capillary length. Frozen muscles were also viewed in cross section. Because the depth of penetration of light was approximately equal to 3 microns, counts of red cell-containing capillary profiles in cross section depend on cell spacing as well as on number of cell-containing flow paths. Counts varied markedly with arterial O2 partial pressure, indicating that the capillary surface area functional for O2 transport changes in response to stress. The adaptive role of change in O2 flux density (flux per area) is discussed in light of new knowledge of tissue O2 gradients.
计算表明，在心肌耗氧量（VO2）的特征下，血浆中的氧分压（PO2）在距红细胞约3微米处降至零（费德尔斯皮尔，W.A.，和A.波佩尔，《微血管研究》32: 164 - 189，1986）。我们测量了原位快速冷冻的大鼠心脏中沿毛细血管的单个红细胞之间的距离。即使在同一毛细血管的分支中，细胞间距也有很大差异。红细胞之间的血浆间隙分为两类，小于5微米的和大于5微米的。平均间隙长度分别为2.1微米和16.5微米。虽然长血浆间隙的数量被低估了，但大于5微米的间隙占观察到的毛细血管长度的三分之一。还对冷冻肌肉进行了横断面观察。由于光的穿透深度约为3微米，横断面中含红细胞的毛细血管轮廓计数既取决于细胞间距，也取决于含细胞流动路径的数量。计数随动脉血氧分压显著变化，表明用于氧气运输的毛细血管表面积会因应激而改变。根据组织氧梯度的新知识，讨论了氧通量密度（每面积通量）变化的适应性作用。
