Marti U, Elsing C, Renner E L, Liechti-Gallati S, Reichen J
Department of Clinical Pharmacology, University of Berne, Switzerland.
J Hepatol. 1996 Apr;24(4):498-502. doi: 10.1016/s0168-8278(96)80172-3.
BACKGROUND/AIMS: Amiloride inhibitable Na+,H(+)-exchange has recently been identified and characterized in rat biliary epithelial cells where its activity at low intracellular pH is significantly higher than in hepatocytes.
Northern blot and reverse transcription-polymerase chain reaction were used to study the expression of the different Na+,H(+)-antiporter isoforms in isolated biliary epithelial cells and hepatocytes.
The present study demonstrates for the first time the expression of Na+,H(+)-antiporter isoform 1 mRNA in rat biliary epithelial cells. Moreover, steady-state levels of this message were several-fold higher in biliary epithelial cells than in hepatocytes. In addition, the expression of Na+,H(+)-antiporter isoform 2 in bile duct epithelial cell but not hepatocytes could be demonstrated by reverse transcription-polymerase chain reaction.
The higher expression of Na+,H(+)-antiporter isoform 1 mRNA may indicate a higher rate of synthesis and therefore a higher Na+,H(+)-exchange activity in biliary epithelial cells than in hepatocytes and is entirely compatible with the results of the previous functional studies.
背景/目的：氨氯地平可抑制的Na⁺，H⁺交换最近在大鼠胆管上皮细胞中被鉴定和表征，其在低细胞内pH值时的活性明显高于肝细胞。
采用Northern印迹法和逆转录-聚合酶链反应研究分离的胆管上皮细胞和肝细胞中不同Na⁺，H⁺逆向转运异构体的表达。
本研究首次证明大鼠胆管上皮细胞中Na⁺，H⁺逆向转运异构体1 mRNA的表达。此外，该信使的稳态水平在胆管上皮细胞中比在肝细胞中高几倍。此外，逆转录-聚合酶链反应可证明胆管上皮细胞而非肝细胞中Na⁺，H⁺逆向转运异构体2的表达。
Na⁺，H⁺逆向转运异构体1 mRNA的较高表达可能表明合成速率较高，因此胆管上皮细胞中的Na⁺，H⁺交换活性高于肝细胞，这与先前的功能研究结果完全一致。
