The effects of nucleotides and potassium channel openers on the SUR2A/Kir6.2 complex K+ channel expressed in a mammalian cell line, HEK293T cells
The effects of nucleotides and potassium channel openers on the SUR2A/Kir6.2 complex K+ channel expressed in a mammalian cell line, HEK293T cells
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核苷酸和钾通道开放剂对哺乳动物细胞系 HEK293T 细胞中表达的 SUR2A/Kir6.2 复合体 K 通道的影响
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
Y. Kurachi
中科院分区：
文献类型：
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作者：
Y. Okuyama;M. Yamada;C. Kondo;E. Satoh;S. Isomoto;T. Shindo;Y. Horio;M. Kitakaze;M. Hori;Y. Kurachi
摘要：采用膜片钳技术检测钾通道开放药物和胞内核苷酸对HEK293T细胞中由SUR2A和Kir6.2组成的ATP敏感K+（KATP）通道的影响。 SUR2A/Kir6.2 通道被吡那地尔有效激活，尼可地尔略有激活，但二氮嗪则不然。吡那地尔激活的通道电流被格列本脲抑制，Ki 值为 160 nM。在形成由内而外 (I-O) 斑块时，出现通道的自发开放，在细胞内 Mg2+ (Mg2+i) 存在和不存在的情况下，细胞内 ATP (ATPi) 均等地抑制该通道。 I-O 补丁中的通道活动逐渐下降。只有在 Mg2+i 存在的情况下，ATPi 才能重新激活耗尽的通道。尿苷 5'-二磷酸 (UDP) 在耗尽之前拮抗 ATPi 介导的通道活性抑制。耗尽后，UDP 激活了通道，但没有对抗 ATPi 介导的通道抑制。因此，SUR2A/Kir6.2在核苷酸调节和药理学方面很好地再现了天然心脏KATP通道的主要特性，因此可以成为阐明KATP通道特征的分子机制的有用工具。
Abstract The effects of potassium channel opening drugs and intracellular nucleotides on the ATP-sensitive K+ (KATP) channel composed of SUR2A and Kir6.2 in HEK293T cells were examined using the patch-clamp technique. The SUR2A/Kir6.2 channel was activated effectively by pinacidil, marginally by nicorandil but not by diazoxide. The pinacidil-activated channel currents were inhibited by glibenclamide with a Ki value of 160 nM. Upon formation of inside-out (I-O) patches, spontaneous openings of the channels appeared, which were inhibited by intracellular ATP (ATPi) equipotently in the presence and in the absence of intracellular Mg2+ (Mg2+i). The channel activity ran-down gradually in I-O patches. The run-down channels could be reactivated by ATPi only in the presence of Mg2+i. Uridine 5’-diphosphate (UDP) antagonized the ATPi-mediated inhibition of the channel activity before run-down. After run-down, UDP activated the channel without antagonizing ATPi-mediated channel inhibition. Thus, the SUR2A/Kir6.2 reproduced the major properties of the native cardiac KATP channel well in terms of nucleotide regulation and pharmacology, and therefore can be a useful tool with which to elucidate the molecular mechanisms characterizing the KATP channel.