Regulation of high-conductance anion channels by G proteins and 5-HT1A receptors in CHO cells.
Regulation of high-conductance anion channels by G proteins and 5-HT1A receptors in CHO cells.
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CHO 细胞中 G 蛋白和 5-HT1A 受体对高电导阴离子通道的调节。
DOI：
10.1152/ajprenal.1993.264.3.f490
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Fitz,JG
中科院分区：
文献类型：
--
作者：
Mangel,AW;Raymond,JR;Fitz,JG
本研究旨在探讨GTP结合蛋白对中国仓鼠卵巢细胞高电导阴离子通道的调控机制。采用膜片钳技术，在由内而外的膜片上测量单通道电流。具有381 +/- 8 pS的单位电导的阴离子选择性通道在48%的切除的斑块中自发激活。在没有自发通道活动的补丁，除了GppNHp，GTP的不可水解的类似物，激活通道的12项研究中的8个，并在补丁与自发通道活动，GppNHp增加开放的概率在4个实验。相反，GDP β S，一种不可水解的GDP类似物，抑制自发和GppNHp诱导的通道活性。在没有自发通道活动的贴片中，8项研究中有5项加入霍乱毒素激活了通道。有趣的是，百日咳毒素也有类似的作用，激活了7个先前静止的斑块中的5个。为了进一步评估抑制性G蛋白在通道调节中的可能作用，在用5-羟色胺5-HT 1A受体转染的细胞中的细胞附着的贴片中测量活性，所述5-羟色胺5-HT 1A受体通过百日咳毒素敏感性G蛋白与效应器机制偶联。用受体激动剂（+/-）-8-羟基-2-（二正丙基氨基）四氢化萘刺激5-HT 1A转染细胞，在标准或高钾溶液中引起开放概率的短暂降低。总之，这些研究结果表明，霍乱和百日咳毒素敏感的G蛋白有助于调节高电导的阴离子通道在CHO细胞。
This study addresses the mechanisms responsible for regulation of high-conductance anion channels by GTP binding proteins in Chinese hamster ovary (CHO) cells. Single-channel currents were measured in inside-out membrane patches using patch-clamp techniques. Anion-selective channels with a unitary conductance of 381 +/- 8 pS activated spontaneously in 48% of excised patches. In patches with no spontaneous channel activity, addition of GppNHp, a nonhydrolyzable analogue of GTP, activated channels in 8 of 12 studies, and in patches with spontaneous channel activity, GppNHp increased open probability in 4 of 4 experiments. In contrast, GDP beta S, a nonhydrolyzable GDP analogue, inhibited both spontaneous and GppNHp-induced channel activity. In patches without spontaneous channel activity, addition of cholera toxin activated channels in five of eight studies. Interestingly, pertussis toxin had a similar effect, activating channels in five of seven previously quiescent patches. To further evaluate the possible role of inhibitory G proteins in channel regulation, activity was measured in cell-attached patches in cells transfected with the serotonin 5-HT1A receptor, which is coupled to effector mechanisms through a pertussis toxin-sensitive G protein. Stimulation of 5-HT1A-transfected cells with the receptor agonist (+/-)-8-hydroxy-2-(di-n-propylamino)tetralin caused a transient decrease in open probability in either standard or high-potassium solutions. In aggregate, these findings suggest that both cholera and pertussis toxin-sensitive G proteins contribute to regulation of high-conductance anion channels in CHO cells.