Role of kinases and phosphatases in the regulation of fluid secretion and Cl-/HCO3- exchange in cholangiocytes
Role of kinases and phosphatases in the regulation of fluid secretion and Cl-/HCO3- exchange in cholangiocytes
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DOI：
10.1152/ajpgi.1997.273.2.g303
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发表时间：
1997-08-01
影响因子：
4.5
通讯作者：
Boyer, JL
中科院分区：
文献类型：
--
作者：
Alvaro, D;Mennone, A;Boyer, JL
采用大鼠离体胆管单元（IBDU）模型，研究了胰泌素刺激胆管上皮分泌液体和碳酸氢盐过程中蛋白激酶A（PKA）、蛋白激酶C（PKC）和蛋白磷酸酶的作用。100 μ M的Sp-cAMPS（一种PKA特异性激动剂）在30分钟灌注期间显著增加分泌（+61%，P < 0.01）。相反，预孵育和灌注Rp-cAMPS，100 μ M，一种特异性PKA抑制剂，降低了促胰液素刺激液体分泌（111 vs. 25%; P < 0.01）和Cl-/HCO 3-交换活性（80 vs. 28%）的能力。无论是PKC激动剂佛波醇12-肉豆蔻酸酯13-乙酸酯，10 μ M，也不是PKC拮抗剂staurosporine表现出任何影响基础或促分泌素刺激的液体分泌或Cl-/HCO 3-交换活动在IBDU。冈田酸，蛋白磷酸酶1和2A的特异性抑制剂，也没有影响基础液分泌或基础活性的Cl-/HCO 3-交换。然而，冈田酸导致分泌的持久性后，去除分泌素，在对照中观察到的分泌减少。这些研究结果表明，PKA，而不是PKC参与分泌素刺激的液体分泌和Cl-/HCO 3-交换活性在大鼠胆管上皮细胞的信号转导，蛋白磷酸酶1和/或2A的去磷酸化失活的过程。
The role of protein kinase A (PKA), protein kinase C (PKC), and protein phosphatases in the process of secretin stimulation of fluid and bicarbonate secretion from biliary epithelium was examined using a novel isolated bile duct unit (IBDU) model from rat liver. Sp-adenosine 3',5'-cyclic monophosphothiolate (Sp-cAMPS), 100 mu M, a PKA-specific agonist, significantly increased secretion during a 30-min perfusion (+61%, P < 0.01). In contrast, preincubation and perfusion of Rp-cAMPS, 100 FIM, a specific PKA inhibitor, reduced the ability of secretin to stimulate both fluid secretion (111 vs. 25%; P < 0.01) and Cl-/HCO3-, exchanger activity (80 vs. 28%). Neither the PKC agonist phorbol 12-myristate 13-acetate, 10 mu M, nor the PKC antagonist staurosporine showed any effect on either basal or secretin-stimulated fluid secretion or Cl-/HCO3- exchange activity in IBDU. Okadaic acid, a specific inhibitor of protein phosphatases 1 and 2A, also had no effect on basal fluid secretion or on the basal activity of the Cl-/HCO3- exchanger. However, okadaic acid resulted in persistence of secretion after removal of secretin, in contrast to the reduction in secretion observed in controls. These findings indicate that PKA but not PKC is involved in the signal transduction of secretin-stimulated fluid secretion and Cl-/HCO3- exchange activity in rat bile duct epithelium, a process inactivated by dephosphorylation by protein phosphatases 1 and/or 2A.