CHARACTERIZATION OF SINGLE PACEMAKER CHANNELS IN CARDIAC SINOATRIAL NODE CELLS
CHARACTERIZATION OF SINGLE PACEMAKER CHANNELS IN CARDIAC SINOATRIAL NODE CELLS
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DOI：
10.1038/324470a0
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发表时间：
1986-12-04
期刊：
影响因子：
64.8
通讯作者：
DIFRANCESCO, D
中科院分区：
文献类型：
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作者：
DIFRANCESCO, D
哺乳动物心脏的正常起搏是由位于窦房结的自发活动细胞驱动的。这些细胞的放电速度和儿茶酚胺对这一速度的调制由IF控制，IF是一种内向的Na-和K-电流，在比−40mV1-9更负的电压下开启。起搏器电流IFI也存在于其他类型的细胞中，它产生和调制去极化过程的能力可能是有用的10。例如，在脊椎动物中，光感受器驱动去极化，从而终止光诱导的超极化11。在海马神经元和背根节神经元12，13也发现了与IF类似的电流。本报告首次表明，通过改进分离的SA结细胞的膜片钳技术14，可以解决单个低电导IF通道的开放问题。肾上腺素对IF的调制是由通道开放概率的增加所介导的，而单通道幅度保持不变。
Normal pacemaking in the mammalian heart is driven by spontaneously active cells located in the sino-atrial (SA) node. The rate of firing of these cells and the modulation of this rate by catecholamines are controlled by if, an inward Na- and K-current that turns on at voltages more negative than −40 mV1–9. The ‘pacemaker’ current ifis also present in other types of cell where its ability to produce and modulate a depolarizing process may be useful10. For example, in vertebrate photoreceptors ifdrives the depolarization that terminates the light-induced hyperpolarization11. Currents similar to ifare also found in hippocampal neurones and DRG neurones12,13. The present report shows for the first time that the opening of single if-channels of low conductance (1 pS) can be resolved using a modification of the patch-clamp technique14on isolated SA-node cells. Modulation of ifby adrenaline is shown to be mediated by an increase in the probability of channel opening, whereas the single-channel amplitude remains unchanged.