EFFECTS OF CALCIUM ON CONDUCTANCE CHANGE OF END-PLATE MEMBRANE DURING ACTION OF TRANSMITTER
EFFECTS OF CALCIUM ON CONDUCTANCE CHANGE OF END-PLATE MEMBRANE DURING ACTION OF TRANSMITTER
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DOI：
10.1113/jphysiol.1963.sp007137
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发表时间：
1963-01-01
影响因子：
5.5
通讯作者：
TAKEUCHI, N
中科院分区：
文献类型：
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作者：
TAKEUCHI, N
通过测量终板电流或ACh电位，研究了钙对青蛙S肌动终板膜电导变化的影响。外加钙离子浓度[Ca]0的增加，使端板电流的反转电位变为负值。增加[Ca]0减小了reversal-potential-external-sodium-concentratlon关系式的斜率，增大了reversal-potential-external-potassium-concentration关系式的斜率。[Ca]0从2 mm增加到30 mm时，ACh产生的端板电流在膜电位为-100 mV时的幅值约为72%，总电导变化约为84%。在80 mM的钙溶液中，显微镜下观察到ACh吸管尖端有微弱的局部性缩短，并伴有较小的ACh电位。镁和钙对ACh电势的逆转作用相似，认为增加[Ca]0可降低ACh产生的终板膜的钠电导，而对钾电导几乎没有影响，而且在ACh作用过程中，终板膜对钙离子的通透性较弱。
The effect of calcium on the conductance change of the end-plate membrane of the frog''s sartortus by transmitter action was studied by measuring the end-plate current or the ACh potential. Increase in the external calcium concentration, [Ca]0, changed the reversal potential of the end-plate current to the negative side. Increasing [Ca]0 reduced the slope of the reversal-potential-external-sodium-concentratlon relation, and increased the slope of the reversal-potential-external-potassium-concentration relation. Increase in [Ca]0 from 2 mM to 30 mM reduced the amplitude of the end-plate current produced by ACh to about 72% at the membrane potential of -100 mV, and reduced the total conductance change to about 84%. In 80 mM-calcium solution a weak localized shortening around the tip of ACh pipette was observed under the microscope, accompanied by a small ACh potential. Magnesium had similar effects to calcium on the reversal level of the ACh potentlaL It is considered that increasing [Ca]0 reduces the sodium conductance of the end-plate membrane produced by ACh with little or no effect on potassium conductance, and furthermore the end-plate membrane may become slightly permeable to calcium ion during the ACh action.