Siflinger-Birnboim A, Bode D C, Malik A B
Department of Physiology and Cell Biology, Albany Medical College, Union University, New York 12208.
Am J Physiol. 1993 Feb;264(2 Pt 2):H370-5. doi: 10.1152/ajpheart.1993.264.2.H370.
We studied the effects of 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) and cholera toxin (CT) on 125I-labeled albumin flux across confluent monolayers of bovine pulmonary microvessel endothelial cells (BMVEC) grown on polycarbonate filters (10(5) BMVEC/filter). 8-BrcAMP and CT increased endothelial adenosine 3',5'-cyclic monophosphate (cAMP) concentrations about twofold. Polymorphonuclear leukocytes (PMN) were layered on BMVEC monolayers (ratio of 10:1) and activated with phorbol 12-myristate 13 acetate (PMA; 5 x 10(-9) M). Transendothelial 125I-labeled albumin clearance rate was measured to determine the endothelial permeability alterations. Activation of PMN in control monolayers resulted in an increase in transendothelial 125I-labeled albumin clearance rate from 0.090 +/- 0.011 to 0.37 +/- 0.06 microliters/min (P < 0.01). Treatment of endothelial monolayers with 8-BrcAMP (10(-3) M) significantly attenuated the increase in endothelial permeability after PMN activation (transendothelial 125I-labeled albumin clearance rate increased to 0.19 +/- 0.03 microliters/min; P < 0.01). Pretreatment of BMVEC monolayers with CT (10(-8) M) for 3 h before PMN activation prevented the PMN-mediated increase in endothelial permeability (125I-labeled albumin clearance rate only increased to 0.13 +/- 0.018 microliters/min). To simulate the effect of PMN activation, hydrogen peroxide (H2O2) was added directly onto BMVEC; both 8-BrcAMP and CT were shown to reduce the H2O2-mediated increase in endothelial permeability. 8-BrcAMP and CT pretreatment did not prevent PMN adhesion to BMVEC monolayer and superoxide anion and H2O2 production after PMA activation of PMN. We conclude that increased endothelial cAMP concentration prevents PMN-mediated endothelial injury by an action of the cyclic nucleotide on endothelial cells.
我们研究了8-溴腺苷3',5'-环磷酸单酯（8-BrcAMP）和霍乱毒素（CT）对在聚碳酸酯滤膜上生长的牛肺微血管内皮细胞（BMVEC，每个滤膜10⁵个BMVEC）汇合单层上¹²⁵I标记白蛋白通量的影响。8-BrcAMP和CT使内皮细胞的腺苷3',5'-环磷酸单酯（cAMP）浓度增加了约两倍。将多形核白细胞（PMN）以10:1的比例铺在BMVEC单层上，并用佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA；5×10⁻⁹ M）激活。通过测量跨内皮¹²⁵I标记白蛋白清除率来确定内皮通透性的改变。在对照单层中激活PMN导致跨内皮¹²⁵I标记白蛋白清除率从0.090±0.011增加到0.37±0.06微升/分钟（P<0.01）。用8-BrcAMP（10⁻³ M）处理内皮单层可显著减轻PMN激活后内皮通透性的增加（跨内皮¹²⁵I标记白蛋白清除率增加到0.19±0.03微升/分钟；P<0.01）。在PMN激活前3小时用CT（10⁻⁸ M）预处理BMVEC单层可防止PMN介导的内皮通透性增加（¹²⁵I标记白蛋白清除率仅增加到0.13±0.018微升/分钟）。为模拟PMN激活的效果，将过氧化氢（H₂O₂）直接添加到BMVEC上；结果显示8-BrcAMP和CT均可降低H₂O₂介导的内皮通透性增加。8-BrcAMP和CT预处理并不能阻止PMN黏附到BMVEC单层以及在PMA激活PMN后超氧阴离子和H₂O₂的产生。我们得出结论，内皮细胞cAMP浓度升高通过环核苷酸对内皮细胞的作用来防止PMN介导的内皮损伤。
