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目的 探讨谷氨酸 (glutamate ,Glu)受体拮抗剂D AP5 (D 2 amino 5 phosphonopentanoate)和CNQX (6 cyano 7 nitroguinoxaline 2 ,3 dione)对Glu调节耳蜗内毛细胞 (innerhailcells ,IHC)游离钙 ([Ca2 + ]i)浓度的影响。方法 在激光共聚焦显微镜下用荧光染料Fluo 3作为指示剂 ,先观察外源性Glu对离体耳蜗IHC胞内 [Ca2 + ]i 浓度的调节作用 ,然后观察D AP5和CNQX对这种调节作用的影响。结果 Glu可增高离体耳蜗IHC内 [Ca2 + ]i 浓度。然而 ,当预先加入 5 0 μmol/L的D AP5时 ,离体耳蜗IHC胞内[Ca2 + ]i 不再增高 ;而预先加入 5 0 μmol/L的CNQX时 ,离体耳蜗IHC胞内 [Ca2 + ]i 仍增高。结论 耳蜗IHC上存在Glu自身受体 ,可能主要为NMDA型 ,AMPA型较少。外源性谷氨酸可以通过耳蜗内毛细胞NMDA自身受体以正反馈方式引起游离钙的增加。
Objective To investigate the effect of glutamate (Glu) receptor antagonist D AP5 (D 2 amino 5 phosphonopentanoate) and CNQX (6 cyano 7 nitroguinoxaline 2, 3 dione) on the regulation of intracellular free calcium in inner hair cells (IHC) [Ca2 +] i) concentration. Methods Fluorescein dye Fluo 3 was used as an indicator to observe the effect of exogenous Glu on [Ca 2+] i concentration in isolated cochlear IHC cells under confocal laser scanning microscope. Then the effects of D AP5 and CNQX on this regulation were observed Impact. Results Glu increased [Ca2 +] i concentration in isolated cochlear IHC. However, intracellular [Ca2 +] i in cochlear IHC was no longer increased when 50 μmol / L DAP5 was added in advance. However, pretreatment with CNQX +] i still increase. Conclusion There are Glu autoreceptors in IHC of cochlea, which may be mainly NMDA type and less AMPA type. Exogenous glutamate can cause an increase in free calcium by positive feedback through NMDA autoreceptors within the hair cells of the cochlear hair.