Conhaim Robert L, Watson Kal E, Heisey Dennis M, Leverson Glen E, Harms Bruce A
Department of Surgery, University of Wisconsin-Madison, Madison, WI 53792-7375, USA.
J Appl Physiol (1985). 2004 Jan;96(1):245-52. doi: 10.1152/japplphysiol.00271.2003. Epub 2003 Sep 5.
Effects of vasoconstriction on the distribution of perfusion among alveoli are not well understood. To address this, we used a new method we developed to determine how microvascular perfusion distribution was affected by a potent vasoconstrictor, the thromboxane receptor analog U-46619. Our method was to infuse 4-microm-diameter fluorescent latex microspheres into the circulation of isolated rat lungs vasoconstricted with U-46619. We used a confocal microscope to image trapping patterns of the particles in dried sections of the lungs and then used dispersion index analysis to quantify the particle patterns in the images, which encompassed approximately 2,000 alveoli. Dispersion indexes revealed significantly more particle clustering (inhomogeneous distribution) in vasoconstricted lungs than in normal flow controls or in controls in which flow was reduced by either lowering pulmonary arterial pressure or raising left atrial pressure. These results suggest that vasoconstriction occurred in the microvessels themselves, which are much smaller vessels than those previously thought to be capable of vasoconstriction.
血管收缩对肺泡间灌注分布的影响尚未完全明确。为了解决这个问题，我们采用了一种新开发的方法，以确定强效血管收缩剂血栓素受体类似物U-46619对微血管灌注分布的影响。我们的方法是将直径为4微米的荧光乳胶微球注入用U-46619进行血管收缩处理的离体大鼠肺循环中。我们使用共聚焦显微镜对肺干燥切片中颗粒的捕获模式进行成像，然后使用离散指数分析对图像中的颗粒模式进行量化，这些图像包含约2000个肺泡。离散指数显示，与正常血流对照组或通过降低肺动脉压或升高左心房压而使血流减少的对照组相比，血管收缩肺中的颗粒聚集（分布不均匀）明显更多。这些结果表明，微血管自身发生了血管收缩，这些微血管比之前认为能够发生血管收缩的血管要小得多。
