Gawlowski D M, Benoit J N, Granger H J
Microcirculation Research Institute, Texas A&M University Health Science Center, College Station 77843.
Am J Physiol. 1993 Feb;264(2 Pt 2):H541-6. doi: 10.1152/ajpheart.1993.264.2.H541.
The effects of leukotriene B4 (LTB4) and N-formyl-methionyl-leucylphenylalanine (FMLP) on transmicrovascular exchange of fluorescein isothiocyanate (FITC)-labeled serum albumin and dextran (molecular mass, 150,000 Da) were evaluated in hamster cheek pouch utilizing measurements of microvascular pressure and global efflux of the macromolecular markers into the tissue suffusate. Exposure of the suffused pouch to 1.0 microM LTB4 failed to alter microvascular pressure from its control level. The microvascular clearance of FITC-albumin rose to a peak value of 1.7 times the control value at a LTB4 concentration of 1.0 microM; the rate of albumin extravasation did not change from the normal level at a concentration of 0.1 microM. The extravasation rate of FITC-dextran was elevated with both doses of LTB4; the leukocyte chemotactic agent elicited 2.4- and 9.7-fold increments in peak clearance of dextran at concentrations of 0.1 and 1.0 microM, respectively. FMLP elicited a twofold increase in venular and terminal arteriolar pressures at a concentration of 1 microM; at the same concentration, the albumin clearance rose 3.5-fold. The results suggest that albumin transport remains near the normal level after LTB4 elicits massive migration of leukocytes across the venular membrane. By contrast, albumin transport is greatly accelerated following exposure to the chemotactic peptide FMLP; ultrastructural and physiological evidence suggests that the leakage of albumin is augmented by increases in microvascular permeability and filtration pressure. The results also reinforce previous ultrastructural observations from our laboratory indicating that diapedesis per se is not a cause of microvascular hyperpermeability in inflammatory reactions.
利用微血管压力测量以及大分子标记物向组织灌流液中的整体外排，在仓鼠颊囊中评估了白三烯B4（LTB4）和N-甲酰甲硫氨酰亮氨酰苯丙氨酸（FMLP）对异硫氰酸荧光素（FITC）标记的血清白蛋白和葡聚糖（分子量150,000道尔顿）跨微血管交换的影响。将灌流的颊囊暴露于1.0微摩尔/升的LTB4，微血管压力未从对照水平改变。在LTB4浓度为1.0微摩尔/升时，FITC-白蛋白的微血管清除率升至对照值的1.7倍的峰值；在浓度为0.1微摩尔/升时，白蛋白外渗率未从正常水平改变。两种剂量的LTB4均使FITC-葡聚糖的外渗率升高；这种白细胞趋化剂在浓度为0.1和1.0微摩尔/升时分别引起葡聚糖峰值清除率增加2.4倍和9.7倍。在浓度为1微摩尔/升时，FMLP使小静脉和终末小动脉压力增加两倍；在相同浓度下，白蛋白清除率上升3.5倍。结果表明，在LTB4引起白细胞大量跨小静脉膜迁移后，白蛋白转运仍接近正常水平。相比之下，暴露于趋化肽FMLP后白蛋白转运大大加速；超微结构和生理学证据表明，微血管通透性和滤过压的增加会增强白蛋白的渗漏。结果还强化了我们实验室先前的超微结构观察结果，表明白细胞渗出本身不是炎症反应中微血管高通透性的原因。
