Calcium currents in interstitial cells from the guinea-pig bladder
Calcium currents in interstitial cells from the guinea-pig bladder
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DOI：
10.1111/j.1464-410x.2006.06156.x
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发表时间：
2006-06-01
影响因子：
4.5
通讯作者：
McCloskey, KD
中科院分区：
文献类型：
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作者：
McCloskey, KD
确定从豚鼠膀胱逼尿肌分离的间质细胞（IC）中是否存在内向电流，如果存在，则使用膜片钳技术和药物对其进行表征。使用全细胞膜片钳技术，研究了从豚鼠膀胱逼尿肌中酶解分离的间质细胞中的内向电流。通过从 - 80 mV 的保持电位正向步进来诱发电流。向外的 K+ 电流被 Cs+ 内部溶液阻挡，以揭示内向电流，该电流在比 - 50 mV 更正的电压下激活，在 0 mV 处达到峰值，在 + 50 mV 附近反转，并在 - 27 mV 处半最大激活。内向电流显示电压依赖性失活并且在-36mV时半最大失活。使用玻尔兹曼函数拟合激活和失活数据显示窗口电流在 - 40 mV 和 + 20 mV 之间。 0 mV 处引起的电流衰减可以用平均时间常数为 88 ms 的单个指数拟合。用 Ba2+ 替换外部 Ca2+ 显着将该时间延长至 344 毫秒。 Ba2+ 和 Bay K 8644 增强了电流幅度。在整个电压范围内，1 μM 硝苯地平显着降低了内向电流，但对 0 mV 引起的电流的阻断比阶跃至 - 20 mV 引起的电流更有效，这可能表明硝苯地平或内向电流的其他成分的作用具有电压依赖性。将药物浓度增加至 10 μM，无论是在 0 mV 还是在 -20 mV 时都没有引起进一步的显着降低。然而，在存在1μM硝苯地平的情况下，后者电流被100μM Ni2+显着降低。两种电流在无Ca2+溶液中均显着降低。豚鼠逼尿肌IC具有内向电流，具有L型Ca2+电流的典型特征。它们还具有内向Ca2+电流的成分，该成分对硝苯地平具有抵抗力，但对Ni2+敏感。需要进一步的工作来表征后者的电导。
To determine whether there are inward currents in interstitial cells (IC) isolated from the guinea-pig detrusor and if so, to characterise them using the patch-clamp technique and pharmacological agents.Using the whole-cell patch-clamp technique, inward currents were studied in IC enzymatically isolated from the detrusor of the guinea-pig bladder. Currents were evoked by stepping positively from a holding potential of - 80 mV.Outward K+ currents were blocked by Cs+ internal solution to reveal inward currents, which activated at voltages more positive than - 50 mV, peaked at 0 mV, reversed near + 50 mV and were half-maximally activated at - 27 mV. The inward currents showed voltage-dependent inactivation and were half-maximally inactivated at - 36 mV. Fitting the activation and inactivation data with a Boltzmann function revealed a window current between - 40 mV and + 20 mV. The decay of the current evoked at 0 mV could be fitted with a single exponential with a mean time-constant of 88 ms. Replacing external Ca2+ with Ba2+ significantly increased this to 344 ms. The current amplitude was augmented by Ba2+, and by Bay K 8644. Inward currents were significantly reduced by 1 mu M nifedipine, across the voltage range, but the blockade was more effective on the current evoked at 0 mV than that evoked by a step to - 20 mV, perhaps indicating voltage-dependence of the action of nifedipine or another component of inward current. Increasing the concentration of the drug to 10 mu M caused no further significant reduction either at 0 mV or at -20 mV. However, in the presence of 1 mu M nifedipine the latter current was significantly reduced by 100 mu M Ni2+. Both currents were significantly reduced in Ca2+-free solution.IC from the guinea-pig detrusor possess inward currents with typical characteristics of L-type Ca2+ current. They also have a component of inward Ca2+ current, which was resistant to nifedipine, but sensitive to Ni2+. Further work is needed to characterise the latter conductance.