TRP channels are involved in mediating hypercapnic Ca2+ responses in rat glia-rich medullary cultures independent of extracellular pH
TRP channels are involved in mediating hypercapnic Ca2+ responses in rat glia-rich medullary cultures independent of extracellular pH
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DOI：
10.1016/j.ceca.2010.07.006
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发表时间：
2010-08-01
期刊：
影响因子：
4
通讯作者：
Oku, Yoshitaka
中科院分区：
文献类型：
--
作者：
Hirata, Yutaka;Oku, Yoshitaka
髓质含有对维持血气和pH稳态很重要的中心化学敏感细胞。为了鉴定内在的化学敏感细胞，我们测量了细胞内Ca2+的反应。（[Ca2+](i)）和H+ ([H+](i))，以及大鼠原代培养的髓细胞暴露于酸中毒6 s时的膜电位。细胞显示短暂的[Ca2+](i)增加到细胞外pH 6.8，这被特异性ASIC1a阻断剂（psalmotoxin-1）抑制，但在hepes缓冲溶液中对pH 7.1没有反应。异己酸酸中毒没有引起[Ca2+]的变化(i)，而高己酸酸中毒在HCO3缓冲溶液（pH 7.1）中诱导了显著的Ca2+反应和膜电位的增加。在富含胶质细胞的培养中，细胞内酸化先于高碳酸酸中毒诱导的Ca2+反应，而乙酰唑胺，一种碳酸酐酶抑制剂抑制了这些反应。瞬态受体电位（TRP）通道广谱阻滞剂Ni2+和钌红，以及TRPV1-和trpm8特异性阻滞剂N-（4-叔丁基苯基）-4-（3-氯吡啶-2-基）-四氢吡嗪-1(2H)-carbox-amide可减弱高糖酸中毒诱导的Ca2+反应。表现出高capic酸中毒诱导的Ca2+反应的细胞亚群也对辣椒素（TRPV1激动剂）和薄荷醇（TRPM8激动剂）的应用有反应。这些结果表明，TRP通道家族通过[H+](i)的变化部分介导高糖酸中毒诱导的快速Ca2+反应，并且是中心化学感应蛋白的候选蛋白。(C) 2010 Elsevier Ltd.版权所有。
The medulla contains central chemosensitive cells important for the maintenance of blood gas and pH homeostasis. To identify the intrinsic chemosensitive cells, we measured responses of intracellular Ca2+. ([Ca2+](i)) and H+ ([H+](i)), and membrane potential of rat primary-cultured medullary cells to 6-s exposure to acidosis.The cells showed transient [Ca2+](i) increases to extracellular pH 6.8, which was inhibited by the specific ASIC1a blocker (psalmotoxin-1), but did not respond to pH 7.1 in the HEPES-buffered solution. Isocapnic acidosis induced no changes in [Ca2+](i), whereas hypercapnic acidosis induced a remarkable Ca2+ response and an increase in membrane potential in the HCO3--buffered solution (pH 7.1). In glia-rich cultures, intracellular acidification preceded the hypercapnic acidosis-induced Ca2+ response, and acetazolamide, a carbonic anhydrase inhibitor suppressed these responses. Transient receptor potential (TRP) channel broad-spectrum blockers Ni2+ and ruthenium red, and a TRPV1- and TRPM8-specific blocker N-(4-tertiarybutylphenyl)-4-(3-chloropyridin-2-yl)-tetrahydropyrazine-1(2H)-carbox-amide attenuated the hypercapnic acidosis-induced Ca2+ response. Subpopulations of cells that exhibited the hypercapnic acidosis-induced Ca2+ response also responded to the application of capsaicin (TRPV1 agonist) and menthol (TRPM8 agonist).These results suggest that the TRP channel family partially mediates the fast hypercapnic acidosis-induced Ca2+ response via changes in [H+](i) and is a candidate of central chemosensing proteins. (C) 2010 Elsevier Ltd. All rights reserved.