Incomplete dissociation of glibenclamide from wild-type and mutant pancreatic K ATP channels limits their recovery from inhibition.
Incomplete dissociation of glibenclamide from wild-type and mutant pancreatic K ATP channels limits their recovery from inhibition.
复制标题
格列本脲与野生型和突变型胰腺 K ATP 通道的不完全解离限制了它们从抑制中恢复。
DOI：
10.1111/j.1476-5381.2008.00005.x
复制
发表时间：
2009
影响因子：
7.3
通讯作者：
Quast,U
中科院分区：
文献类型：
--
作者：
Russ,U;Kuhner,P;Prager,R;Stephan,D;Bryan,J;Quast,U
背景和目的：抗糖尿病的磺脲类药物格列本脲通过抑制胰腺ATP敏感的K+(KATP)通道起作用，KATP通道是KIR6.2和磺脲受体1 (KIR6.2/SUR1)4的四聚体复合物。在室温下，格列本脲冲洗后通道活性的恢复非常缓慢，无法测量。本研究探讨了格列本脲抑制下通道活性恢复与[3H]‐格列本脲在37℃下从通道解离率之间的关系。实验方法：KIR6.2, KIR6.2ΔN5或KIR6.2ΔN10（后者分别缺乏氨基末端残基2-5或2-10）与SUR1在HEK细胞中共表达。在37℃下测定了[3H]‐格列本脲与通道的解离和格列本脲抑制下通道活性的恢复。关键结果：[3H]‐格列本脲从野生型通道的解离动力学遵循指数衰减，解离半时间t1/2(D) = 14 min；然而，仅观察到有限和缓慢的通道活动恢复。KIR6.2ΔN5/SUR1通道的t1/2(D)为5.3 min，通道活动的恢复表现出缓慢的s型时间过程，一半时间，t1/2(R) = 12 min。t1/2(D)为ΔN10通道2.3 min；恢复动力学在t1/2(R) ~ 4 min内再次呈s型曲线。结论和意义：格列本脲从截断的通道中解离是通道恢复的限速步骤。s型恢复动力学与格列本脲在通道重新打开之前必须从所有四个（或至少三个）位点解离的模型定量一致。有人认为，这些结论也适用于野生型（胰腺）KATPchannel。
Background and purpose:The antidiabetic sulphonylurea, glibenclamide, acts by inhibiting the pancreatic ATP‐sensitive K+(KATP) channel, a tetradimeric complex of KIR6.2 and sulphonylurea receptor 1 (KIR6.2/SUR1)4. At room temperature, recovery of channel activity following washout of glibenclamide is very slow and cannot be measured. This study investigates the relation between the recovery of channel activity from glibenclamide inhibition and the dissociation rate of [3H]‐glibenclamide from the channel at 37°C.Experimental approach:KIR6.2, KIR6.2ΔN5 or KIR6.2ΔN10 (the latter lacking amino‐terminal residues 2–5 or 2–10 respectively) were coexpressed with SUR1 in HEK cells. Dissociation of [3H]‐glibenclamide from the channel and recovery of channel activity from glibenclamide inhibition were determined at 37°C.Key results:The dissociation kinetics of [3H]‐glibenclamide from the wild‐type channel followed an exponential decay with a dissociation half‐time,t1/2(D) = 14 min; however, only limited and slow recovery of channel activity was observed.t1/2(D) for KIR6.2ΔN5/SUR1 channels was 5.3 min and recovery of channel activity exhibited a sluggish sigmoidal time course with a half‐time,t1/2(R) = 12 min.t1/2(D) for the ΔN10 channel was 2.3 min; recovery kinetics were again sigmoidal witht1/2(R) ∼4 min.Conclusions and implications:The dissociation of glibenclamide from the truncated channels is the rate‐limiting step of channel recovery. The sigmoidal recovery kinetics are in quantitative agreement with a model where glibenclamide must dissociate from all four (or at least three) sites before the channel reopens. It is argued that these conclusions hold also for the wild‐type (pancreatic) KATPchannel.