EFFECT OF NITROGEN-DIOXIDE ON SURFACE-MEMBRANE FLUIDITY AND INSULIN-RECEPTOR BINDING OF PULMONARY ENDOTHELIAL-CELLS
EFFECT OF NITROGEN-DIOXIDE ON SURFACE-MEMBRANE FLUIDITY AND INSULIN-RECEPTOR BINDING OF PULMONARY ENDOTHELIAL-CELLS
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DOI：
10.1016/0006-2952(88)90011-1
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发表时间：
1988-04-15
影响因子：
5.8
通讯作者：
RAIZADA, MK
中科院分区：
文献类型：
--
作者：
PATEL, JM;EDWARDS, DA;RAIZADA, MK
二氧化氮（NO2）是一种有害的氧化性污染物，可使肺细胞膜脂过氧化。我们评估了NO2改变培养的猪肺动脉内皮细胞表面膜流动性、脂质组成和胰岛素受体结合的能力。暴露于5 ppm NO2 3 - 24小时后，用1-（4-三甲基氨基苯基）-6-苯基-1，3，5-己三烯（TMA-DPH）或荧光胺（与表面磷脂和蛋白质的氨基共价结合的荧光分子探针）标记细胞，1-（4-trimethylaminophenyl）-6-phenyl-1，3，5-hexatriene（TMA-DPH）是一种阳离子荧光芳烃，锚定为脂-水界面。通过监测TMA-DPH和荧光胺的稳态荧光各向异性（rs）的变化来测量膜流动性。通过测量125I-胰岛素的时间依赖性结合来监测胰岛素特异性受体结合。NO_2暴露后，TMA-DPH和荧光胺的rs值随时间的延长而显著升高，在24小时时达到最大值（P <0.001）。在离体质膜以及从内皮细胞或其质膜的总脂质提取物制备的脂质囊泡中观察到rs值的类似增加。与对照组相比，NO2暴露24小时的细胞脂质提取物中磷脂酰乙醇胺和磷脂酰丝氨酸含量显著增加，而暴露3 - 12小时的细胞则无此现象。与对照细胞相比，暴露于NO_2 12和24小时（而不是3和6小时）的125I-胰岛素与细胞的特异性结合显著降低（P <0.05）。结合数据的Scatchard分析表明，NO2暴露导致内皮细胞中胰岛素受体结合位点减少5倍。NO2暴露后24小时恢复，但不是没有，更换培养基。这些结果表明，NO2暴露导致肺内皮细胞质膜表面脂质结构域中脂质物理状态的可逆变化，这些变化可能会干扰质膜依赖性功能，如受体-配体相互作用。
Nitrogen dioxide (NO2), an evironmental oxidant pollutant, is known to peroxidize membrane lipids of lung cells. We evaluated the ability of NO2 to alter the surface membrane fluidity, lipid composition, and insulin receptor binding of porcine pulmonary artery endothelial cells in culture. After 3- to 24-hr exposure to 5 ppm NO2, cells were labeled with either 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH), a cationic fluorescent aromatic hydrocarbon that anchors as the lipid-water interface, or fluorescamine, a fluorescent molecular probe that covalently binds with amino groups of surface phospholipids and proteins. Membrane fluidity was measured by monitoring changes in the steady-state fluorescence anisotropies (rs) for TMA-DPH and fluorescamine. Insulin specific receptor binding was monitored by measuring time-dependent binding of 125I-insulin. Following NO2 exposure, rs values for TMA-DPH and fluorescamine were increased significantly in a time-dependent fashion, with maximum increases at 24 hr (P < 0.001). Similar increases in rs values were observed in isolated plasma membranes as well as in lipid vesicles prepared from total lipid extracts of endothelial cells or their plasma membranes. Phosphatidylethanolamine plus phosphatidylserine content in lipid extracts from 24-hr but not 3- to 12-hr NO2-exposed cells was increased significantly (P < 0.01) compared to control cells. Specific binding of 125I-insulin to cells exposed to NO2 for 12 and 24 hr (but not 3 and 6 hr) was reduced significantly (P < 0.05) compared to binding in control cells. Scatchard analysis of the binding data indicated that NO2 exposure caused a 5-fold reduction in insulin receptor binding sites in endothelial cells. Recovery was achieved 24 hr after NO2 exposure with, but not without, changing culture medium. These results indicate that NO2 exposure causes reversible changes in the physical state of lipids in the superficial lipid domains of the pulmonary endothelial cell plasma membrane, and these alterations may interfere with plasma membrane-dependent functions such as receptor-ligand interaction.