Ion permeation and conduction in a human recombinant 5-HT3 receptor subunit (h5-HT3A)
Ion permeation and conduction in a human recombinant 5-HT3 receptor subunit (h5-HT3A)
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DOI：
10.1111/j.1469-7793.1998.653bs.x
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发表时间：
1998-03-15
影响因子：
5.5
通讯作者：
Peters, JA
中科院分区：
文献类型：
--
作者：
Brown, AM;Hope, AG;Peters, JA
1.采用膜片钳技术的全细胞记录模式，对在人胚肾细胞系（HEK 293）中表达的人重组同源寡聚5-HT 3受体（h5-HT 3A）进行了表征. 5-KT诱发的瞬时内向电流（EC 50 = 3.4 μ M; Hill系数= 1.8）被5-HT 3受体拮抗剂昂丹司琼（IC 50 = 103 pM）和非选择性药物甲氧氯普胺（IC 50 = 69 nM）、可卡因（IC 50 = 459 nM）和（+）-筒箭毒碱（IC 50 = 2.8 μ M）阻断。5-HT诱导的电流在-2.2 mV的电位下向内整流并符号反转（E5-HT）。N-甲基-D-葡糖胺具有良好的渗透性。渗透率比P-Na/P-Cs和P-NMDG/P-Cs分别为0.90和0.083。通过测量Ca 2+和Mg 2+替代Na+的介质中的E5-HT来评估对二价阳离子的渗透性。计算出P-Ca/P-Cs和P-Mg/P-Cs分别为1.00和0.61。从宏观电流的波动分析估计的单通道弦电导（γ）随着膜超极化从-40 mV的243 fS增加到-100 mV的742 fS。将[Ca 2 +]（o）从2降低至0.1 mM引起5-HT诱发的全细胞电流增加。[Mg 2 +]（o）的伴随减少产生进一步的增强作用。波动分析表明，电压无关的伽马增强有助于这种现象。这些数据表明，由h5-HT 3A亚基组成的同源寡聚受体形成向内整流的低电导的阳离子选择性离子通道，其可渗透Ca 2+和Mg 2+。
1. A human recombinant homo-oligomeric 5-HT3 receptor (h5-HT3A) expressed in a human embryonic kidney cell line (HEK 293) was characterized using the whole-cell recording configuration of the patch clamp technique.2. 5-KT evoked transient inward currents (EC50 = 3.4 mu M; Hill coefficient = 1.8) that were blocked by the 5-HT3 receptor antagonist ondansetron (IC50 = 103 pM) and by the nonselective agents metoclopramide (IC50 = 69 nM), cocaine (IC50 = 459 nM) and (+)-tubocurarine (IC50 = 2.8 mu M).3. 5-HT-induced currents rectified inwardly and reversed in sign (E5-HT) at a potential of -2.2 mV. N-Methyl-D-glucamine was finitely permeant. Permeability ratios P-Na/P-Cs and P-NMDG/P-Cs were 0.90 and 0.083, respectively.4. Permeability towards divalent cations was assessed from measurements of E5-HT in media where Ca2+ and Mg2+ replaced Na+.P-Ca/P-Cs and P-Mg/P-Cs were calculated to be 1.00 and 0.61, respectively.5. Single channel chord conductance (gamma) estimated from fluctuation analysis of macroscopic currents increased with membrane hyperpolarization from 243 fS at -40 mV to 742 fS at -100 mV.6. Reducing [Ca2+](o) from 2 to 0.1 mM caused an increase in the whole-cell current evoked by 5-HT. A concomitant reduction in [Mg2+](o) produced further potentiation. Fluctuation analysis indicates that a voltage-independent augmentation of gamma contributes to this phenomenon.7. The data indicate that homo-oligomeric receptors composed of h5-HT3A subunits form inwardly rectifying cation-selective ion channels of low conductance that are permeable to Ca2+ and Mg2+.