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近几年,有关肝细胞机制、激素调节和胆管细胞的作用等新领域的研究,使对胆汁形成的机制和调节有了进一步理解。肝细胞是种极性上皮细胞细胞的高度极性表现为从窦区(基底外侧区)向小管区(顶区)转运。Na~+-K~+ATP 酶位于基底外侧膜,它产生离子梯度,驱动二级和三级主动转运器完成此定向运输。转运器协同窦区摄取并最终经小管排出胆汁酸、脂类、蛋白质和其他阴阳离子。肝细胞也先将所有新合成的质膜蛋白质运至基底外侧区,再将顶膜蛋白质运至小管区。相邻肝细胞之间紧密连接的细胞骨架成分构成两个膜区的屏障来维持细胞极性。此旁细胞屏障的通透性受激素控制。
In recent years, researches in new fields such as hepatocyte mechanism, hormone regulation and the function of cholangiocytes have further understanding of the mechanism and regulation of bile formation. Hepatocytes are highly polar cells of polar epithelial cells that appear to be transported from sinus (basolateral region) to tubule (apical region). Na ~ + -K ~ + ATPase is located on the basolateral membrane, which produces an ion gradient that drives secondary and tertiary active transporters to accomplish this directional transport. The transporter, in concert with the sinus area, eventually excretes bile acids, lipids, proteins and other anions through the tubules. The hepatocytes also transport all newly synthesized plasma membrane proteins to the basolateral region, and then transport the apical membrane proteins to the tubule. The cytoskeletal components that are closely linked between adjacent hepatocytes constitute a barrier to both membrane regions to maintain cellular polarity. The paracellular barrier permeability is controlled by hormones.