A novel KATP current in cultured neonatal rat atrial appendage cardiomyocytes
A novel KATP current in cultured neonatal rat atrial appendage cardiomyocytes
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DOI：
10.1161/01.res.85.8.707
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发表时间：
1999-10-15
影响因子：
20.1
通讯作者：
Baertschi, AJ
中科院分区：
文献类型：
--
作者：
Baron, A;van Bever, L;Baertschi, AJ
在原代培养的乳鼠心耳心肌细胞上研究了ATP敏感性K+（K-ATP）通道的功能和药理学特性。全细胞内向整流K+电流的激活依赖于移液管ATP浓度，并与接近K+平衡电位的膜超极化相关。K-ATP电流既可自发激活，也可通过将电解液的渗透压从290 mOsm/kg H2O降低到260 mOsm/kg H2O引起的膜低渗牵张或K+通道开放剂二氮嗪和色满卡林（EC 50分别约为1和10 nmol/L）激活。激活的心房K-ATP电流对格列本脲高度敏感，IC 50为1.22+/-0.15 nmol/L。在由内而外的斑片中记录的新生儿心房K-ATP通道显示电导为58.0+/-2.2 pS，以133.8+/-20.4 ms的持续时间的爆发式开放，其中开放持续时间为1.40+/-0.10 ms，负电位的关闭持续时间为0.66+/-0.04 ms。该通道在0.1 mmol/L ATP时有半最大开放概率，可被100 μ mol/L二氮嗪激活，并被格列本脲抑制，IC 50在纳摩尔范围内。因此，在低浓度K-ATP通道开放剂的进一步测试之前，单通道数据证实了全细胞记录获得的结果。因此，新生儿心耳K-ATP通道显示出独特的功能和药理学特征，其与胰腺β细胞通道相似，对格列本脲和二氮嗪具有高亲和力，并且其电导率也与心室通道亚型相似，对色满卡林具有高亲和力，其爆发持续时间和对ATP的敏感性。逆转录-聚合酶链反应实验显示Kir6.1、Kir6.2、SUR 1A、SUR 1B、SUR 2A和SUR 2B亚基的表达，这一发现支持新生儿心房K-ATP通道对应于K-ATP通道亚基的新型异源多聚体关联的假设。
The functional and pharmacological properties of ATP-sensitive K+ (K-ATP) channels were studied in primary cultured neonatal rat atrial appendage cardiomyocytes. Activation of a whole-cell inward rectifying K+ current depended on the pipette ATP concentration and correlated with a membrane hyperpolarization close to the K+ equilibrium potential. The K-ATP current could be activated either spontaneously or by a hypotonic stretch of the membrane induced by lowering the osmolality of the bathing solution from 290 to 260 mOsm/kg H2O or by the K+ channel openers diazoxide and cromakalim with EC50 approximate to 1 and 10 nmol/L, respectively. The activated atrial K-ATP current was highly sensitive to glyburide, with an IC50 of 1.22+/-0.15 nmol/L. Recorded in inside-out patches, the neonatal atrial K-ATP channel displayed a conductance of 58.0+/-2.2 pS and opened in bursts of 133.8+/-20.4 ms duration, with an open time duration of 1.40+/-0.10 ms and a close time duration of 0.66+/-0.04 ms for negative potentials. The channel had a half-maximal open probability at 0.1 mmol/L ATP, was activated by 100 mu mol/L diazoxide, and was inhibited by glyburide, with an IC50 in the nanomolar range. Thus, pending further tests at low concentrations of K-ATP channel openers, the single-channel data confirm the results obtained with whole-cell recordings. The neonatal atrial appendage K-ATP channel thus shows a unique functional and pharmacological profile resembling the pancreatic beta-cell channel for its high affinity for glyburide and diazoxide and for its conductance, but also resembling the ventricular channel subtype for its high affinity for cromakalim, its burst duration, and its sensitivity to ATP. Reverse transcriptase-polymerase chain reaction experiments showed the expression of Kir6.1, Kir6.2, SUR1A, SUR1B, SUR2A, and SUR2B subunits, a finding supporting the hypothesis that the neonatal atrial K-ATP channel corresponds to a novel heteromultimeric association of K-ATP channel subunits.