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Title:: Analyze of ion currents of desensitization to acetylcholine on sinoatrial node cells in rabbit hearts

作者:: 干晓江¹ ; 臧伟进¹; 臧益民; Haruo Honjo³ ; Mark Boyett³; 1, 西安交通大学医学院药理学教研室，陕西西安710061;2.第四军医大学生理学教研室; 3．英国里兹大学生理学教研室

Author(s):: YU Xiao-jiang¹; ZANG Wei-jin ¹．ZANG Yi-min ²; HONJO Haruo ³; BOYETT Mark³; 1．Department of Pharmacology， Xi'an Jiaotong University，Xi'an Shaanxi 710061，China; 2．Department of Physiology，Fourth Military Medical University;3．Department of Physiology University of Leeds LS2 9JT，UK

关键词:: 离子通道; 乙酰胆碱; 窦房结细胞; 脱敏

Keywords:: ion channels; acetylcholine; sinoatrial node cells; desensitization

分类号:: Q425

DOI:: -

文献标识码:: A

摘要:: 目的探讨迷走神经递质乙酰胆碱(ACh)对家兔窦房结细胞动作电位、毒荤碱型钾离子流(Ix )、钙离子液(ICa及超极化激活的离子流(I )的影响及脱敏可能的离子机制。方法采用全细胞膜片钳技术分别记录了单个家兔窦房结细胞的各种通道离子液及动作电位。结果 ①当给单个心脏窦房结细胞灌注ACh时，可使其自发电活动减慢，甚至消失而当持续灌注ACh时，可出现其负性变率作用的脱敏现象．即尽管ACh持续存在，窦房结细胞的自发电活动逐渐恢复。②ACh可以激活IK，IK 随着ACh的持续灌注可出现脱敏现象．③ACh对“基础”钙离子流(I)无明显作用，但当钙离子流被B受体激动剂异丙肾上腺素增大之后，ACh可以降低此钙通道离子流。ACh的作用并未出现脱敏现象。④ACh可以降低单个窦房结细胞的超极化激活的离子流(L)．这个效应也没有脱敏的现象。结论 ACh对心脏所致的负性变率作用的脱敏现象主要是毒草碱型钾通道I 脱敏的缘故。

Abstract:: AIM To investigate the effects and mechanism of acetylcholine(ACh) on desensitization of action potential，calcium current(1c)．the hyperpolarization activated current(I) and ACh induced potassium current(1K,Ach)in rabbit sinoatrial node cells．METHODS We were using the whole cell patch clamp techniques to record the various ion currents and action potentials in single sinoatrial mode cells isolated from rabbit hearts．RESULTS ①We observed that the activation of the channel by ACh results in a slowing down or cease of the spontaneous activity in single sinoatrial node cells．During an exposure to ACh the negative chronotropic effect of ACh fades and the spontaneous activity resumed despite the continuous presence of ACh．② Ach activated an inward rectifying potassium current(1K．Ach)．which faded in the continuous presence of ACh. ③ACh had no effect on“basal”L-type calcium current，hut ACh decreased lc which had been potentiated by β-agonist，isoprenaline．This effect did not fade during exposure to ACh．④ACh decreased Ir current and this effect again did not fade．CONCLUSION Desensitization of negative chronotropic response to ACh is mostly the result of fade of IK, Ach．

参考文献/References

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乙酰胆碱对心脏窦房结脱敏的离子流分析(PDF)

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