Intrinsic gating of inward rectifier in bovine pulmonary artery endothelial cells in the presence or absence of internal Mg2+.
Intrinsic gating of inward rectifier in bovine pulmonary artery endothelial cells in the presence or absence of internal Mg2+.
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DOI：
10.1085/jgp.96.1.109
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发表时间：
1990-07
期刊：
影响因子：
--
通讯作者：
DeCoursey TE
中科院分区：
文献类型：
--
作者：
Silver MR;DeCoursey TE
内向整流（IR）电流进行了研究，在牛肺动脉内皮细胞的全细胞配置的膜片钳技术与细胞外的K+浓度，[K+]o，范围从4.5至160 mM。无论是在细胞内的溶液中的游离Mg 2+的浓度，[Mg 2 +]i，是1.9 mM或名义上为0，IR表现出电压和时间依赖性门控。IR电导被超极化激活，被去极化失活。小的稳态外向IR电流比K+反转电位EK高出约40 mV，与[Mg2+]i无关。作为一个一阶C在平衡O门控过程建模，开放率，α，和关闭率，β，是指数依赖于电压，与β更陡峭的电压依赖性，改变9 mV的e倍相比，18 mV的e倍变化的α。在所有研究的[K+]o中，α和β的电压依赖性随EK沿着移动，这是其他细胞中IR通道的特征。门控过程的稳态电压依赖性很好地描述了玻尔兹曼函数。无论[Mg 2 +]i如何，在所有[K+]o中，半活化电位平均约为7 mV负向于观察到的反转电位。当使用不含Mg的移液器溶液（斜率因子，4.3 mV）时，活化曲线比移液器含有1.9 mM Mg2+（5.2 mV）时略陡。这些数据的最简单的解释是，在牛肺动脉内皮细胞的IR通道有一个内在的门控机制，这不是由于镁块。
Inward rectifier (IR) currents were studied in bovine pulmonary artery endothelial cells in the whole-cell configuration of the patch-clamp technique with extracellular K+ concentrations, [K+]o, ranging from 4.5 to 160 mM. Whether the concentration of free Mg2+ in the intracellular solution, [Mg2+]i, was 1.9 mM or nominally 0, the IR exhibited voltage- and time-dependent gating. The IR conductance was activated by hyperpolarization and deactivated by depolarization. Small steady-state outward IR currents were present up to approximately 40 mV more positive than the K+ reversal potential, EK, regardless of [Mg2+]i. Modeled as a first-order C in equilibrium O gating process, both the opening rate, alpha, and the closing rate, beta, were exponentially dependent on voltage, with beta more steeply voltage dependent, changing e-fold for 9 mV compared with 18 mV for an e-fold change in alpha. Over all [K+]o studied, the voltage dependence of alpha and beta shifted along with EK, as is characteristic of IR channels in other cells. The steady-state voltage dependence of the gating process was well described by a Boltzmann function. The half-activation potential was on average approximately 7 mV negative to the observed reversal potential in all [K+]o regardless of [Mg2+]i. The activation curve was somewhat steeper when Mg-free pipette solutions were used (slope factor, 4.3 mV) than when pipettes contained 1.9 mM Mg2+ (5.2 mV). The simplest interpretation of these data is that IR channels in bovine pulmonary artery endothelial cells have an intrinsic gating mechanism that is not due to Mg block.