Cyclic AMP activates anion channels in cultured bovine corneal endothelial cells
Cyclic AMP activates anion channels in cultured bovine corneal endothelial cells
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DOI：
10.1006/exer.1997.0290
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发表时间：
1997-06-01
影响因子：
3.4
通讯作者：
Srinivas, SP
中科院分区：
文献类型：
--
作者：
Bonanno, JA;Srinivas, SP
腺苷通过cAMP依赖性机制刺激角膜内皮的离子偶联液体转运。本研究检查了cAMP和腺苷是否能增强阴离子电导。Cl-通量，测量的变化，在荧光的Cl-敏感染料SPQ，以下删除或重新加入Cl-林格，可以加速20 μ M毛喉素或10 μ M腺苷。cAMP混合物（20 μ M forskolin + 100 μ M IBMX + 100 μ M cpt-cAMP）对静息[Cl-]无影响（i）。然而，当Cl-内流被100 μ M呋塞米抑制时，观察到响应cAMP混合物的净Cl-流出。单独暴露于cAMP混合物使静息膜电位去极化。相反地，cAMP混合物在细胞中引起相对超极化，这些细胞先前已经去极化超过Cl-（ECl-）的平衡电位，通过应用1 μ M短杆菌肽D，膜电位中cAMP依赖性的变化可以被50 μ M NPPB抑制，但不能被200 μ M DPC、100 μ M H2 DIDS或50 μ M格列本脲抑制。总之，这些结果与NPPB敏感的cAMP激活的Cl-通道一致。为了检查这些通道是否可渗透HCO 3-，在不存在Na+的情况下，在酸化和去极化细胞中测量响应cAMP混合物的pHi变化。cAMP鸡尾酒引起的增加，只有当HCO 3-存在时，与HCO 3-流入。对照组HCO;环磷酸腺苷鸡尾酒引起pHi的短暂降低，这不能解释为Na+：nHCO（3）（-）共转运的抑制或Cl-/HCO（3-）交换的刺激。这些结果与通过cAMP激活通道的传导性HCO 3流出一致。我们的结论是，培养的牛角膜内皮细胞具有cAMP激活的阴离子通道。(C)出版社：Academic Press Limited。
Ion coupled fluid transport by the corneal endothelium is stimulated by adenosine through a cAMP dependent mechanism. This study examines if anion conductance is enhanced by cAMP and, hence by adenosine. Cl- fluxes, measured by changes in fluorescence of the Cl- sensitive dye SPQ, following removal or re-addition of Cl- Ringer, could be accelerated by 20 mu M forskolin or 10 mu M adenosine. The cAMP cocktail (20 mu M forskolin + 100 mu M IBMX + 100 mu M cpt-cAMP) had no effect on resting [Cl-](i). However, when Cl- influx was inhibited by 100 mu M furosemide, net Cl- efflux was observed in response to the cAMP cocktail, Exposure to the cAMP cocktail alone depolarized the resting membrane potential. Conversely, the cAMP cocktail caused a relative hyperpolarization in cells which had been previously depolarized beyond the equilibrium potential for Cl- (ECl-), by application of 1 mu M Gramicidin D, cAMP dependent changes in membrane potential could be inhibited by 50 mu M NPPB, but not by 200 mu M DPC, 100 mu M H2DIDS or 50 mu M glibenclamide. Taken together, these results are consistent with NPPB-sensitive, cAMP activated Cl- channels. To examine if these channels are permeable to HCO3-, changes in pHi in response to the cAMP cocktail were measured in acidified and depolarized cells in the absence of Na+. The cAMP cocktail caused an increase in pHi only when HCO3- was present, consistent with HCO3- influx. In control HCO; Ringer, the cAMP cocktail caused a transient decrease in pHi, which could not be accounted for by inhibition of Na+:nHCO(3)(-), cotransport or stimulation of Cl-/HCO3-, exchange. These results are consistent with conductive HCO3- efflux through cAMP activated channels. We conclude that cultured bovine corneal endothelial cells possess cAMP activated anion channels. (C) 1997 Academic Press Limited.