Rosario J, Sutherland E, Zaccaro L, Simon F R
Department of Medicine, University of Colorado School of Medicine, Denver 80262.
Biochemistry. 1988 May 31;27(11):3939-46. doi: 10.1021/bi00411a008.
Administration of high-dose ethinylestradiol to rats decreases bile flow, Na,K-ATPase specific activity, and liver plasma membrane fluidity. By use of highly purified sinusoidal and bile canalicular membrane fractions, the effect of ethinylestradiol administration on the protein and lipid composition and fluidity of plasma membrane fractions was examined. In sinusoidal fractions, ethinylestradiol (EE) administration decreased Na,K-ATPase activity (32%) and increased activities of alkaline phosphatase (254%), Mg2+-ATPase (155%), and a 160-kDa polypeptide (10-fold). Steady-state and dynamic fluorescence polarization was used to study membrane lipid structure. Steady-state polarization of diphenylhexatriene (DPH) was significantly higher in canalicular compared to sinusoidal membrane fractions. Ethinylestradiol (5 mg/kg per day for 5 days) selectively increased sinusoidal polarization values. Similar changes were demonstrated with the probes 2- and 12-anthroyloxystearate. Time-resolved fluorescence polarization measurements indicated that EE administration for 5 days did not change DPH lifetime but increased the order component (r infinity) and decreased the rotation rate (R). However, 1 and 3 days after EE administration and with low doses (10-100 micrograms/kg per day for 5 days) the Na,K-ATPase, bile flow, and order component were altered, but the rotation rate was unchanged. Vesicles prepared from total sinusoidal membrane lipids of EE-treated rats, as well as phospholipid vesicles, demonstrated increased DPH polarization, as did intact plasma membrane fractions. Liver plasma membrane fractions showed no change in free cholesterol or cholesterol/phospholipid molar ratio, while esterified cholesterol content was increased with high-dose but not low-dose ethinylestradiol.(ABSTRACT TRUNCATED AT 250 WORDS)
给大鼠施用高剂量乙炔雌二醇会降低胆汁流量、钠钾 - 三磷酸腺苷酶（Na,K - ATPase）的比活性以及肝细胞膜流动性。通过使用高度纯化的肝血窦和胆小管膜组分，研究了施用乙炔雌二醇对细胞膜组分的蛋白质和脂质组成及流动性的影响。在肝血窦组分中，施用乙炔雌二醇（EE）会降低Na,K - ATPase活性（32%），并增加碱性磷酸酶（254%）、镁离子 - 三磷酸腺苷酶（Mg2 + - ATPase，155%）和一种160 kDa多肽（10倍）的活性。采用稳态和动态荧光偏振来研究膜脂质结构。与肝血窦膜组分相比，二苯基己三烯（DPH）在胆小管中的稳态偏振显著更高。乙炔雌二醇（每天5 mg/kg，持续5天）选择性地增加了肝血窦的偏振值。使用探针2 - 和12 - 蒽氧基硬脂酸酯也显示出类似变化。时间分辨荧光偏振测量表明，施用EE 5天不会改变DPH寿命，但会增加有序成分（r∞）并降低旋转速率（R）。然而，在施用EE 1天和3天后以及低剂量（每天10 - 100微克/千克，持续5天）时，Na,K - ATPase、胆汁流量和有序成分发生了改变，但旋转速率未变。从EE处理大鼠的总肝血窦膜脂质制备的囊泡以及磷脂囊泡，与完整的细胞膜组分一样，显示出DPH偏振增加。肝细胞膜组分的游离胆固醇或胆固醇/磷脂摩尔比没有变化，而高剂量而非低剂量的乙炔雌二醇会增加酯化胆固醇含量。（摘要截断于250字）
