Regulation of biliary secretion through apical purinergic receptors in cultured rat cholangiocytes
Regulation of biliary secretion through apical purinergic receptors in cultured rat cholangiocytes
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DOI：
10.1152/ajpgi.1997.273.5.g1108
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发表时间：
1997-11-01
影响因子：
4.5
通讯作者：
Fitz, JG
中科院分区：
文献类型：
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作者：
Schlenker, T;Romac, JMJ;Fitz, JG
为了评估胆汁中的三磷酸腺苷是否作为信号因子调节胆管分泌，采用一种新的正常大鼠胆管细胞(NRC)模型进行了电压钳研究。在阿米洛利(100 MU M)阻断Na+通道的情况下，顶膜暴露于ATP后，短路电流(I-sc)从18.2+/-5.9增加到52.8+/-12.7 mA(n=18)。对三磷酸腺苷的反应是由基侧到顶端的氯离子转运介导的，因为它被1)氯离子通道阻滞剂4，4‘-二异硫氰基二苯乙烯-2，2’-二磺酸(1 MM)、二苯基邻氨基苯甲酸(1.5 mM)或5-硝基-2-(3-苯丙氨基)苯甲酸(50或100 mM)所抑制，2)钾通道阻滞剂Ba2+(5 MM)，或3)基底侧小室中的Na+-K+-2Cl(-)共转运剂布美坦(200 MM)。其他核苷酸刺激ISC的作用顺序为UTP=ATP=腺苷5‘-O-(3)-硫代三磷酸，与P-2U嘌呤能受体一致。ADP、AMP、2-甲基硫代腺苷、5‘-三磷酸和腺苷无作用。从肝脏cDNA文库中分离到一个编码大鼠P-2U受体(RP(2U)R)的基因，该基因在非洲爪哇卵母细胞中的功能表达导致了具有相似药理特征的ATP刺激电流的出现。Northern分析在NRC以及大鼠肝脏的其他细胞类型中发现了杂交的mRNA转录本。这些结果表明，极化的胆管细胞暴露于三磷酸腺苷通过激活顶膜上的P-2U受体而导致腔内氯离子的分泌。胆汁中释放的三磷酸腺苷可能是调节胆管细胞分泌功能的自分泌或旁分泌信号。
To evaluate whether ATP in bile serves as a signaling factor regulating ductular secretion, voltage-clamp studies were performed using a novel normal rat cholangiocyte (NRC) model. In the presence of amiloride (100 mu M) to block Na+ channels, exposure of the apical membrane to ATP significantly increased the short-circuit current (I-sc) from 18.2 +/- 5.9 to 52.8 +/- 12.7 mu A (n = 18). The response to ATP is mediated by basolateral-to-apical Cl- transport because it is inhibited by 1) the Cl- channel blockers 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (1 mM), diphenylanthranilic acid (1.5 mM), or 5-nitro-2-(3-phenylpropylamino)benzoic acid (50 or 100 mu M) in the apical chamber, 2) the K+ channel blocker Ba2+ (5 mM), or 3) the Na+-K+-2Cl(-) cotransport inhibitor bumetanide (200 mu M) in the basolateral chamber. Other nucleotides stimulated an increase in Isc with a rank order potency of UTP = ATP = adenosine 5'-O-(3)-thiotriphosphate, consistent with P-2u purinergic receptors. ADP, AMP, 2-methylthioadenosine 5'-triphosphate, and adenosine had no effect. A cDNA encoding a rat P-2u receptor (rP(2u)R) was isolated from a liver cDNA library, and functional expression of the corresponding mRNA in Xenopus laevis oocytes resulted in the appearance of ATP-stimulated currents with a similar pharmacological profile. Northern analysis identified hybridizing mRNA transcripts in NRC as well as other cell types in rat liver. These findings indicate that exposure of polarized cholangiocytes to ATP results in luminal Cl- secretion through activation of P-2u receptors in the apical membrane. Release of ATP into bile may serve as an autocrine or paracrine signal regulating cholangiocyte secretory function.