Mammalian retinal bipolar cells express inwardly rectifying K+ currents (IKir) with a different distribution than that of Ih
Mammalian retinal bipolar cells express inwardly rectifying K+ currents (IKir) with a different distribution than that of Ih
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DOI：
10.1152/jn.00426.2003
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发表时间：
2003-11-01
影响因子：
2.5
通讯作者：
Pan, ZH
中科院分区：
文献类型：
--
作者：
Ma, YP;Cui, JJ;Pan, ZH
视网膜双极细胞包括多种亚型，这些亚型因其生理特性的多样性而众所周知。我们采用全细胞膜片钳技术研究了哺乳动物视网膜双极细胞超极化激活电流的特性和功能作用。我们报告，双极细胞表达内向整流K+电流（I-Kir）除了超极化激活的阳离子电流（I-H）以前报道。此外，这两种电流在双极细胞的不同亚型中差异表达。其中一组视锥双极细胞主要显示I-Kir。第二组锥双极细胞显示两种电流，但具有更大的I-h。另一方面，视杆双极细胞主要显示I-h。此外，我们发现，I-Kir和I-h差异影响双极细胞的电压响应：I-h促进和/或加速膜电位反弹，而I-Kir抵消或防止这种反弹。I-Kir在双极细胞中的表达以及I-h和I-Kir在双极细胞中的差异表达可能为理解双极细胞的生理特性提供新的见解。
Retinal bipolar cells comprise multiple subtypes that are well known for the diversity of their physiological properties. We investigated the properties and functional roles of the hyperpolarization-activated currents in mammalian retinal bipolar cells using whole cell patch-clamp recording techniques. We report that bipolar cells express inwardly rectifying K+ currents (I-Kir) in addition to the hyperpolarization-activated cationic currents (I-h) previously reported. Furthermore, these two currents are differentially expressed among different subtypes of bipolar cells. One group of cone bipolar cells in particular displayed mainly I-Kir. A second group of cone bipolar cells displayed both currents but with a much larger I-h. Rod bipolar cells, on the other hand, showed primarily I-h. Moreover, we showed that I-Kir and I-h differentially influence the voltage responses of bipolar cells: I-h facilitates and/or accelerates the membrane potential rebound, whereas I-Kir counteracts or prevents such rebound. The findings of the expression of I-Kir and the differential expression of I-h and I-Kir in bipolar cells may provide new insights into an understanding of the physiological properties of bipolar cells.