Ichimura Hideo, Parthasarathi Kaushik, Issekutz Andrew C, Bhattacharya Jahar
lung Biology Laboratory, Department of Physiology and Cellular Biophysics, Columbia University, New York, New York, USA.
Am J Physiol Lung Cell Mol Physiol. 2005 Sep;289(3):L407-12. doi: 10.1152/ajplung.00048.2005. Epub 2005 May 6.
Although pressure elevation in lung postcapillary venules increases endothelial P-selectin expression, the extent to which P-selectin causes lung leukocyte margination remains controversial. To address this issue, we optically viewed postcapillary venules of the isolated blood-perfused rat lung by real-time fluorescence imaging. To determine leukocyte margination in single postcapillary venules, we quantified the fluorescence of leukocytes labeled in situ with rhodamine 6G (R6G). Although baseline fluorescence was sparse, a 10-min pressure elevation by 10 cmH(2)O markedly increased R6G fluorescence. Both stopping blood flow during pressure elevation and eliminating leukocytes from the perfusion blocked the fluorescence increase, affirming that these fluorescence responses were attributable to pressure-induced leukocyte margination. A P-selectin-blocking MAb and the L- and P-selectin blocker fucoidin each inhibited the fluorescence increase, indicating that P-selectin was critical for inducing margination. Time-dependent imaging of blood-borne fluorescent beads revealed reduction of plasma velocity during pressure elevation. After pressure returned to baseline, a similar reduction of plasma velocity, established by manually decreasing the perfusion rate, prolonged margination. Our findings show that in lung postcapillary venules, the decrease in plasma velocity critically determines pressure-induced leukocyte margination.
尽管肺毛细血管后微静脉内压力升高会增加内皮细胞P选择素的表达，但P选择素导致肺白细胞边缘化的程度仍存在争议。为解决这一问题，我们通过实时荧光成像对离体血液灌注大鼠肺的毛细血管后微静脉进行了光学观察。为了确定单个毛细血管后微静脉中的白细胞边缘化情况，我们对用罗丹明6G（R6G）原位标记的白细胞荧光进行了定量。尽管基线荧光稀疏，但10 cmH₂O的压力升高10分钟显著增加了R6G荧光。在压力升高期间停止血流以及从灌注液中去除白细胞均阻断了荧光增加，证实这些荧光反应归因于压力诱导的白细胞边缘化。一种P选择素阻断单克隆抗体以及L和P选择素阻断剂岩藻依聚糖均抑制了荧光增加，表明P选择素对诱导边缘化至关重要。对血源性荧光珠进行的时间依赖性成像显示，压力升高期间血浆流速降低。压力恢复到基线后，通过手动降低灌注速率建立的类似血浆流速降低延长了边缘化。我们的研究结果表明，在肺毛细血管后微静脉中，血浆流速降低是压力诱导白细胞边缘化的关键决定因素。
