Barrand M A, Robertson K J, von Weikersthal S F
Department of Pharmacology, University of Cambridge, UK.
FEBS Lett. 1995 Oct 30;374(2):179-83. doi: 10.1016/0014-5793(95)01104-m.
In vivo expression of P-glycoprotein in isolated rat brain microvessels is compared with that in vitro in primary cultures of brain endothelial cells. More P-glycoprotein is detected by Western immunoblotting in microvessels than in cultured endothelium. RT-PCR with isoform-specific primers and immunoblotting with a mdr1b-specific antibody reveals only mdr1a in vivo but both mdr1a and mdr1b in vitro. Thus mdr1a decreases whereas mdr1b increases during culture. P-Glycoprotein activity is evident in vitro, with resistance modulators, e.g. verapamil, producing increases in intracellular [3H]vincristine accumulation. Endothelial cells cultured from epididymal fat pad microvasculature and aorta contain little or no P-glycoprotein. Here, resistance modulators are less effective.
将分离的大鼠脑微血管中P-糖蛋白的体内表达与脑内皮细胞原代培养物中的体外表达进行比较。通过蛋白质免疫印迹法检测到，微血管中的P-糖蛋白比培养的内皮细胞中的更多。用亚型特异性引物进行逆转录聚合酶链反应（RT-PCR）以及用mdr1b特异性抗体进行免疫印迹分析显示，体内仅存在mdr1a，而体外则同时存在mdr1a和mdr1b。因此，在培养过程中mdr1a减少而mdr1b增加。P-糖蛋白活性在体外很明显，抗性调节剂（如维拉帕米）可使细胞内[3H]长春新碱蓄积增加。从附睾脂肪垫微血管和主动脉培养的内皮细胞几乎不含或不含有P-糖蛋白。在此，抗性调节剂的效果较差。
