Sadurski R, Tsukada H, Ying X, Bhattacharya S, Bhattacharya J
Department of Medicine, St. Luke's-Roosevelt Hospital Center, College of Physicians and Surgeons, Columbia University, New York, New York 10019.
J Appl Physiol (1985). 1994 Aug;77(2):718-25. doi: 10.1152/jappl.1994.77.2.718.
We report a new method for precise quantification of lung microvascular diameter. Isolated blood-perfused rat lungs (500-g Sprague-Dawley rats) at constant inflation pressure [alveolar pressure (PA)] and stopped blood flow were viewed by microscopy and video. Subpleural venules of the second and third postcapillary generations were microinjected with oil colored with Sudan Black. Vascular pressure (Pvas) was varied in steps, and at each step the horizontal diameter (DH) and the length of the oil-filled segment were determined by microcaliper measurements of the replayed video image. At PA = 5 cmH2O, a decrease in Pvas from 25 to 0 cmH2O decreased DH in the second-generation venules from 55 +/- 2 (SE) to 41 +/- 1 microns (n = 13) and in the third-generation venules from 96 +/- 6 to 73 +/- 6 microns (n = 6). The constant-volume oil-filled segment conformed to the cylinder formula in that decreases in DH correlated linearly with 1/ square root of length, thereby indicating that at all Pvas values venular geometry was constant and probably circular in cross section. The decrease in Pvas to -5 cmH2O did not further decrease DH. At Pvas = 10-25 cmH2O, an increase in PA to 15 cmH2O did not significantly increase DH, although the increase in PA did diminish the slope (compliance) of the DH-Pvas relationship in second- but not third-generation venules. We conclude that 1) lung expansion decreases compliance of juxtacapillary venules, 2) venules retain circular cross sections at Pvas between -5 and 25 cmH2O, and 3) venules are patent at subzero Pvas.
我们报告了一种精确量化肺微血管直径的新方法。在恒定充气压力[肺泡压（PA）]下，对离体血液灌注的大鼠肺（500克的斯普拉格-道利大鼠）进行观察，停止血流后通过显微镜和视频进行观察。对第二和第三级毛细血管后微静脉的胸膜下微静脉注射用苏丹黑染色的油。逐步改变血管压力（Pvas），在每个步骤中，通过对重放的视频图像进行微卡尺测量来确定水平直径（DH）和充满油的节段长度。在PA = 5 cmH₂O时，Pvas从25降至0 cmH₂O，使第二代微静脉的DH从55±2（标准误）降至41±1微米（n = 13），第三代微静脉的DH从96±6降至73±6微米（n = 6）。恒定体积的充满油的节段符合圆柱体公式，即DH的减小与1/长度平方根呈线性相关，从而表明在所有Pvas值下微静脉的几何形状是恒定的，并且横截面可能是圆形的。Pvas降至 -5 cmH₂O时，DH没有进一步减小。在Pvas = 10 - 25 cmH₂O时，将PA增加到15 cmH₂O并没有显著增加DH，尽管PA的增加确实减小了第二代而非第三代微静脉中DH - Pvas关系的斜率（顺应性）。我们得出以下结论：1）肺扩张会降低毛细血管旁微静脉的顺应性；2）在Pvas介于 -5和25 cmH₂O之间时，微静脉保持圆形横截面；3）在低于零的Pvas下微静脉仍然通畅。
