【摘 要】
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Calcium-activated chloride channels (CaCC) play fundamental roles in numerous physiological processes.Despite their physiological importance, the molecular identity of CaCC has not been fully investig
【机 构】
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School of Sciences,Hebei University of Technology,Tianjin 300130,China
【出 处】
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The 3rd Ion Channel Conference: Ion channels-Structure, Func
论文部分内容阅读
Calcium-activated chloride channels (CaCC) play fundamental roles in numerous physiological processes.Despite their physiological importance, the molecular identity of CaCC has not been fully investigated till now.Recently, transmembrane 16A (TMEM 16A) was demonstrated by three independent research groups as the strong candidate of the CaCCs molecular basis.To further investigate the electrophysiological characteristics, we constructed TMEM16A(abcd) stably transfected HEK293 cell lines, and carried out whole-ceil and excised inside-out patch clamp experiments.We found that TMEM 16A channel was Ca2+-dependent in both patch configurations.It could be strongly inhibited by niflumic acid (NFA), and when the Cl-were substituted by gluconate ions, the current reduced considerably.In inside-out configuration, TMEM16A channel was time-independent but voltage-dependent, in which the half maximum activating free Ca2+ concentration was 63 nM at 80 mV.While in whole-cell configuration, the current was both time-and voltage-dependent.About the rectification feature, we also obtained distinct results in the two patch configurations.In whole-cell, TMEM16A channel expressed outward rectification in low Ca2+ concentration, but when Ca2+ concentration grew high, it became linear.On the contrary, in inside-out, it always expressed outward rectification.Comparison the different characteristics in the two configurations, there must have some underlying mechanisms to be identified, which we discussed in respect of direct or indirect activation.There was irreversible rundown in this channel.It will provide some useful clues for the current activation character for the diversity of various channel sources and could be foundation of further pathological and pharmacological research in related diseases.
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