Chari R S, Schutz S M, Haebig J E, Shimokura G H, Cotton P B, Fitz J G, Meyers W C
Department of Surgery, Duke University, North Carolina, USA.
Am J Physiol. 1996 Feb;270(2 Pt 1):G246-52. doi: 10.1152/ajpgi.1996.270.2.G246.
Activation of purinergic receptors by ATP stimulates Cl- efflux in biliary epithelial cells. To determine whether purinergic agonists are present under physiological conditions, we have assayed mammalian bile for nucleotides and assessed whether hepatoma and cholangiocarcinoma cell lines are capable of nucleotide release. Bile samples were collected from human, rat, and pig donors and assayed for nucleotide concentrations by luminometry. ATP, ADP, and AMP were present in bile from each species, and the average total nucleotide concentration in human bile was 5.21 +/- 0.91 microM (n = 16). In an in vitro model of HTC rat hepatoma cells or Mz-ChA-1 cholangiocarcinoma cells on a superfused column, nucleotides were present in the effluent from each cell type. Addition of alpha, beta-methyleneadenosine 5'-diphosphate (50 microM) to inhibit 5'-nucleotidase activity increased AMP concentrations two- to threefold. Exposure to forskolin (100 microM) or ionomycin (2 microM) stimulated nucleotide release from cholangiocarcinoma but not hepatoma cells. These studies indicate that adenosine nucleotides are present in bile in concentrations sufficient to activate purinergic receptors. Purinergic receptor activation by local nucleotide release might constitute an autocrine and/or paracrine mechanism for modulation of biliary secretion.
ATP激活嘌呤能受体可刺激胆管上皮细胞中的氯离子外流。为了确定在生理条件下是否存在嘌呤能激动剂，我们检测了哺乳动物胆汁中的核苷酸，并评估肝癌和胆管癌细胞系是否能够释放核苷酸。从人类、大鼠和猪的供体收集胆汁样本，并用发光法检测核苷酸浓度。每种动物的胆汁中都存在ATP、ADP和AMP，人胆汁中核苷酸的平均总浓度为5.21±0.91微摩尔/升（n = 16）。在HTC大鼠肝癌细胞或Mz-ChA-1胆管癌细胞的体外模型中，在超灌流柱上，每种细胞类型的流出物中都存在核苷酸。添加α,β-亚甲基腺苷5'-二磷酸（50微摩尔）以抑制5'-核苷酸酶活性，可使AMP浓度增加两到三倍。用福斯可林（100微摩尔）或离子霉素（2微摩尔）处理可刺激胆管癌细胞而非肝癌细胞释放核苷酸。这些研究表明，胆汁中存在的腺苷核苷酸浓度足以激活嘌呤能受体。局部核苷酸释放激活嘌呤能受体可能构成调节胆汁分泌的自分泌和/或旁分泌机制。
