神经肌肉传导电生理.ppt

神经肌肉传导电生理

Acetylcholinecurare是一种取自热带植物的剧毒药物，被南美的土著猎人用作制作毒箭的材料curare

AcetylcholineBernard认为Curare的作用位点是神经与肌肉相接触的区域（ＮＭＪ）JohnLangley发现Nicotine能刺激蛙的离体骨骼肌的收缩，但Curare会使Nicotine失效1906JohnLangley提出化学递质假说1921Loewi发现化学递质－Ach

Acetylcholine

神经-肌接头NMJ

(neuromuscularjunction)

运动区皮质 皮质脊髓纤维皮质脊髓束脊髓前角运动神经元突触连接NMJ骨骼肌

nAchRArthurKarlinnAchR是一个五聚体α亚基2个β、δ亚基各一个ε或γ亚基

nAchRAChAlphaAlphaEpsilon/GammaDeltaBetaIonChannelAChInfetaldenervatedreceptors:GammareplacesEpsilon

nAchR

nAchRImmatureSpreadUnstable?life24hrsLongerburstdurationSmallerconductance2-10timeslongerchannelopening(slowclosing)MatureLocalizedStable?life2weeksBurstactivityNormalconductanceChannelopensfor0.5millisecond

nAchR10%receptorsmustbeopenformuscleactionpotentialgeneration70%receptorscanbeoccupiedbeforefadeisobserved95%receptoroccupancyrequiredforcompletetwitchsuppression

NMJ突触机制

NMJ突触机制 K+Na+Ca2+

NMJ突触机制 Ca+

K+Na+Na+Na+Na+Na+Na+Na+Na+Na+Na+Na+Na+K+K+K+K+K+K+K+K+K+K+K+AChAChAChAChNa+Na+K+MusclemembraneNerveterminalCa2+Ca2+

EPPAPMusclemembranePresynapticterminalMuscleMembraneVoltage(mV)Time(msec)-90mVVKVNa0ThresholdPresynapticAPEPPAChReceptorChannelsVoltage-gatedNaChannelsInwardRectifierKChannels

Meanwhile...AChAChunbindsfromitsreceptorMusclemembraneAChsothechannelclosesAChAChNerveterminalAChishydrolyzedbyAChEintoCholineandacetateCholineAcetateCholineistakenupintonerveterminalCholineCholineresynthesizedintoAChandrepackagedintovesicleACh

肌紧张产生的突触机制运动神经末梢去极化?前膜Ca2+通透性??前膜释放Ach?Ach与终板膜受体结合?Na+Ca2+内流，K+外流?EPP?AP?兴奋收缩耦联

AP(actionpotential)膜对Na+、K+通透性（电导）改变锋电位=Na+平衡电位

AP(actionpotential)上升支Na+内流Na+的平衡电位下降支K+外流负后电位K+外流暂时性减弱正后电位Na+-K+泵的活动动作电位示意图

总结AchnAchRNMJAP

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