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KMID : 0811720070110000077
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Korean Journal of Physiology & Pharmacology
2007 Volume.11 No. 0 p.77 ~ p.0
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Arachidonic Acid-induced Activation of Large-conductance Potassium Channels and Membrane Hyperpolarization in Mouse B cells
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Zheng Haifeng
Nam Joo-Hyun
Yen Nguen-Hoang
Kang Tong-Mook
Earm Yung E
Kim Sung-Joon
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Abstract
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Arachidonic acids (AA) have attracted attention because of their potential immune regulatory effects. Here we compared the effects of AA on membrane currents, voltages and cytoplasmic Ca2+ concentration ([Ca2+]c) of mouse B cell lines (WEHI-231 and Bal-17), and mouse splenic B cells. Lymphocytes commonly express voltage-gated K+ channels (Kv) and Ca2+-activated K+ channels (IKCa1). Recently, we found that WEHI-231 and splenic B cells express novel type of K+ channels called Large conductance background K+ channels (LKbg)(Nam et al., 2004; 2007). In whole-cell patch clamp, both Kv and IKCa1 were inhibited by AA. AA activated background-type K+ current and nonselective cationic (NSC) current in WEHI-231 while only NSC current in Bal-17. Inside-out patch clamp study showed that AAs directly activates LKbg. AA induced hyperpolarization of WEHI-231 and depolarization of Bal-17 cells, respectively. In the splenic B cells, AA also activated LKbg and induced membrane hyperpolarization. In fura-2 spectrofluorimetry, AA induced persistent increase in [Ca2+]c of WEHI-231 and splenic B cells, and these response were attenuated by KCl-induced depolarization. In Bal-17 cell, however, AA induced only a transient increase of [Ca2+]c. In summary, AA activate LKbg activation and hyperpolarize WEHI-231 cells and splenic B cells, and this provides electrical driving force of the sustained Ca2+ influx. The K+ efflux combined with strong Ca2+ response might play a role in the modulation of B cell immune reaction.
Grant support: This work was supported by grant R01-2005-000-10231-0 from the Korea Science & Engineering Foundation.
Source: Korean Journal of Physiology & Pharmacology.2007 Oct;11(Suppl II):S77-S77
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KEYWORD
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Mouse, B lymphocyte, Arachidonic acid, Potassium channel
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