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首页> 外文OA文献 >Synergistic activation of non-rectifying small-conductance chloride channels by forskolin and phorbol esters in cell-attached patches of the human colon carcinoma cell line HT-29cl.19A
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Synergistic activation of non-rectifying small-conductance chloride channels by forskolin and phorbol esters in cell-attached patches of the human colon carcinoma cell line HT-29cl.19A

机译：在人类结肠癌细胞系HT-29cl.19A的细胞贴片中，福司柯林和佛波醇酯对非整流性小传导氯离子通道的协同激活

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textabstractCell-attached patch-clamp studies with the human colon carcinoma HT-29cl.19A cells revealed a small chloride channel with a unitary conductance of 6.5 pS at 70 mV and 4.6 pS at -70 mV clamp potential after cAMP was increased by activation of adenylyl cyclase by forskolin. Usually channels inactivated upon patch excision, but in a few excised patches the channels stayed active and displayed a linear I/V relation in symmetrical (150 mmol/l) chloride solutions with a conductance of 7.5 pS. A 16-fold increase in channel incidence was observed when forskolin and phorbol 12,13-dibutyrate (PDB) were present together. The open probability was voltage-independent and was not different in the presence of forskolin plus PDB or with forskolin alone. The conductance sequence of the channel as deduced from outward currents carried by five different anions including chloride was: Cl->Br->NO3 ->gluconate > I-. The permeability sequence deduced from the reversal potentials was NO3 -≥Br->Cl->I->gluconate. With iodide in the pipette the conductance decreased strongly. Moreover, the inward current was reduced by 61%, indicating a strong inhibition of the chloride efflux by iodide. Similarly, the forskolin-induced increase of the short-circuit current (Isc) in confluent filter-grown monolayers was strongly reduced by iodide in the apical perfusate. Iodide also increased the fractional resistance of the apical membrane and repolarized the membrane potential, indicating an inhibitory action on the forskolin-induced increase of the apical chloride conductance. The PDB-induced Isc was also reduced by iodide, suggesting that the same chloride conductance is involved in the forskolin and in the PDB response. The results suggest that forskolin via cAMP-dependent protein kinase and PDB via protein kinase C regulate the same non-rectifying small-conductance chloride channels in the HT-29cl.19A cells.
机译：textabstract用人结肠癌HT-29cl.19A细胞进行的细胞附着膜片钳研究显示，在cAMP通过腺苷酸激活而增加后，一个小的氯离子通道在70 mV时的单位电导为6.5 pS，在-70 mV时的单位电导为4.6 pS。佛司可林的环化酶。通常，通道在贴片切除后会失活，但在一些切下的贴片中，通道保持活动状态，并在对称（150 mmol / l）氯化物溶液中以7.5 pS的电导率显示线性I / V关系。当福斯高林和12,13-二丁酸佛波醇（PDB）一起存在时，观察到通道发生率增加了16倍。打开概率与电压无关，在存在福司可林加PDB或单独使用福司可林的情况下没有差异。由五个不同的阴离子（包括氯离子）携带的向外电流推导的通道电导序列为：Cl-> Br-> NO3->葡萄糖酸> I-。由反向电位推导的渗透率序列为NO3-≥Br-> Cl-> I->葡萄糖酸盐。在移液管中加入碘化物后，电导会大大降低。此外，内向电流减少了61％，表明碘化物对氯离子的流出有很强的抑制作用。类似地，顶端灌洗液中的碘化物可大大减少融合蛋白生长的单层中福司可林诱导的短路电流（Isc）的增加。碘化物还增加了顶膜的分数电阻并使膜电位重新极化，表明对福司可林诱导的顶氯离子电导率增加具有抑制作用。碘化物还可以降低PDB诱导的Isc，这表明相同的氯化物电导与毛喉素和PDB反应有关。结果表明，通过cAMP依赖性蛋白激酶引起的毛喉素和通过蛋白激酶C引起的PDB调节HT-29cl.19A细胞中相同的非整流性小传导氯离子通道。

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