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Mammalian retinal bipolar cells express inwardly rectifying K+ currents (IKir) with a different distribution than that of Ih.

Authors
  • Ma, Yu-Ping
  • Cui, Jinjuan
  • Hu, Hui-Juan
  • Pan, Zhuo-Hua
Type
Published Article
Journal
Journal of neurophysiology
Publication Date
Nov 01, 2003
Volume
90
Issue
5
Pages
3479–3489
Identifiers
PMID: 14615436
Source
Medline
License
Unknown

Abstract

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 (IKir) in addition to the hyperpolarization-activated cationic currents (Ih) 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 IKir. A second group of cone bipolar cells displayed both currents but with a much larger Ih. Rod bipolar cells, on the other hand, showed primarily Ih. Moreover, we showed that IKir and Ih differentially influence the voltage responses of bipolar cells: Ih facilitates and/or accelerates the membrane potential rebound, whereas IKir counteracts or prevents such rebound. The findings of the expression of IKir and the differential expression of Ih and IKir in bipolar cells may provide new insights into an understanding of the physiological properties of bipolar cells.

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