Parker J C, Ivey C L
Department of Physiology, University of South Alabama, Mobile, Alabama 36688, USA.
J Appl Physiol (1985). 1997 Dec;83(6):1962-7. doi: 10.1152/jappl.1997.83.6.1962.
To separate the contributions of cellular and basement membrane components of the alveolar capillary barrier to the increased microvascular permeability induced by high pulmonary venous pressures (Ppv), we subjected isolated rat lungs to increases in Ppv, which increased capillary filtration coefficient (Kfc) without significant hemorrhage (31 cmH2O) and with obvious extravasation of red blood cells (43 cmH2O). Isoproterenol (20 microM) was infused in one group (Iso) to identify a reversible cellular component of injury, and residual blood volumes were measured to assess extravasation of red blood cells through ruptured basement membranes. In untreated lungs (High Ppv group), Kfc increased 6.2 +/- 1.3 and 38.3 +/- 15.2 times baseline during the 31 and 43 cmH2O Ppv states. In Iso lungs, Kfc was 36.2% (P < 0.05) and 64.3% of that in the High Ppv group at these Ppv states. Residual blood volumes calculated from tissue hemoglobin contents were significantly increased by 53-66% in the high Ppv groups, compared with low vascular pressure controls, but there was no significant difference between High Ppv and Iso groups. Thus isoproterenol significantly attenuated vascular pressure-induced Kfc increases at moderate Ppv, possibly because of an endothelial effect, but it did not affect red cell extravasation at higher vascular pressures.
为了区分肺泡毛细血管屏障的细胞成分和基底膜成分对高肺静脉压（Ppv）所致微血管通透性增加的作用，我们对离体大鼠肺施加Ppv升高处理，在无明显出血（31 cmH₂O）时增加了毛细血管滤过系数（Kfc），在有明显红细胞外渗（43 cmH₂O）时也增加了Kfc。在一组（异丙肾上腺素组）中输注异丙肾上腺素（20 μM）以确定损伤的可逆细胞成分，并测量残余血容量以评估红细胞通过破裂基底膜的外渗情况。在未处理的肺（高Ppv组）中，在31 cmH₂O和43 cmH₂O的Ppv状态下，Kfc分别比基线增加了6.2±1.3倍和38.3±15.2倍。在异丙肾上腺素组的肺中，在这些Ppv状态下，Kfc分别为高Ppv组的36.2%（P<0.05）和64.3%。与低血管压对照组相比，高Ppv组中根据组织血红蛋白含量计算的残余血容量显著增加了53% - 66%，但高Ppv组和异丙肾上腺素组之间无显著差异。因此，异丙肾上腺素在中等Ppv时显著减弱了血管压力诱导的Kfc增加，这可能是由于内皮效应，但在较高血管压力下它不影响红细胞外渗。
