SEPARATE CL- CONDUCTANCES ACTIVATED BY CAMP AND CA-2+ IN CL--SECRETING EPITHELIAL-CELLS
SEPARATE CL- CONDUCTANCES ACTIVATED BY CAMP AND CA-2+ IN CL--SECRETING EPITHELIAL-CELLS
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DOI：
10.1073/pnas.87.13.4956
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发表时间：
1990-07-01
影响因子：
11.1
通讯作者：
FRIZZELL, RA
中科院分区：
文献类型：
--
作者：
CLIFF, WH;FRIZZELL, RA
我们利用全细胞膜片钳技术研究了cAMP-和Ca2+激活的Cl-在分泌Cl的结肠上皮细胞系T84中的传导。在电压钳下测量Cl-和K+电流。Forskolin或cAMP使Cl-电流增加2-15倍，而K+电流没有变化。camp激活的Cl-电流在-100 ~ 100 mV范围内呈线性关系，且在电压脉冲期间电流变化不随时间变化。Ca2+离子载体或移液管Ca2+的增加使Cl-和K+电流增加2-30倍。Ca2+激活的Cl-电流向外整流，在去极化电压脉冲期间激活，在超极化电压脉冲期间失活。福斯可林后加入离子载体可使Cl-电导进一步提高1.5 ~ 5倍，电流呈现Ca2+刺激的时间依赖性特征。因此，cAMP和Ca2+激活了具有不同性质的Cl-电导，这意味着这些第二信使激活了不同的Cl-通道，或者它们在同一Cl-通道中诱导了不同的导电和动力学状态。
We studied the cAMP- and Ca2+-activated secretory Cl- conductances in the Cl-secreting colonic epithelial cell line T84 using the whole-cell patch-clamp technique. Cl- and K+ currents were measured under voltage clamp. Forskolin or cAMP increased Cl- current 2-15 times with no changes in K+ current. The current-votage relation for cAMP-activated Cl- current was linear from -100 to 100 mV and showed no time-dependent changes in current during voltage pulses. Ca2+ ionophores or increased pipette Ca2+ increased both Cl- and K+ currents 2-30 times. The Ca2+ -activated Cl- current was outwardly rectified, activated during depolarizing voltage pulses, and inactivated during hyperpolarizing voltage pulses. Addition of ionophore after forskolin further increased Cl- conductance 1.5-5 times, and the current took on the time-dependent characteristics of that stimulated by Ca2+. Thus, cAMP and Ca2+ activated Cl- conductances with different properties, implying that these second messengers activate different Cl- channels or that they induce different conductive and kinetic states in the same Cl- channel.