PERMEATION OF CALCIUM THROUGH EXCITATORY AMINO-ACID RECEPTOR CHANNELS IN CULTURED RAT HIPPOCAMPAL-NEURONS
PERMEATION OF CALCIUM THROUGH EXCITATORY AMINO-ACID RECEPTOR CHANNELS IN CULTURED RAT HIPPOCAMPAL-NEURONS
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DOI：
10.1113/jphysiol.1990.sp018060
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发表时间：
1990-05-01
影响因子：
5.5
通讯作者：
TSUZUKI, K
中科院分区：
文献类型：
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作者：
IINO, M;OZAWA, S;TSUZUKI, K
1.用全细胞电压钳技术在培养的大鼠海马神经元上记录N-甲基-D-天冬氨酸（NMDA）、使君子酸（quisqualate）和红藻氨酸（kainate）诱导的电流。为了分离由Ca 2+和其他二价阳离子（Sr 2+、Ba 2+、Mn 2+和Mg 2+）携带的内向电流，将对照外溶液中的Na+和K+两者用不渗透阳离子N-甲基葡糖胺（NMG）替代。2.用NMG替代Na+、K+和Ca ~（2+）可阻断NMDA、quisqualate和kinate诱导的内向电流。在Na ~+-、K ~+-free（简称Na ~+-free）溶液中，含10 mM-Ca ~（2+）的NMDA在-60mV引起明显的内向电流。在该内部溶液含有165 mM-Cs+的溶液中，NMDA诱导电流的反转电位为-5.0 ±-。0.7 mV（n = 36），表明根据恒定场方程，Ca 2+和Cs+的渗透系数之比的值为PCa/PC = 6.2。3.在含有10 mM-Sr ~（2+）、Ba ~（2+）或Mn ~（2+）的无Na ~+、Ca ~（2+）溶液中，NMDA在-60 mV下引起内向电流反应，但在无Na ~（2+）、10 mM-Mg ~（2+）溶液中不引起内向电流反应。基于反转电位测量，确定二价阳离子中NMDA受体通道的渗透性顺序为Ba 2+（1.2）> Ca 2+（1.0）> Sr 2+（0.8）> Mn 2+（0.3）. mchgt。Mg ~（2+）< 0.02。4.在无Na+、10 mM-Ca 2+溶液中，使君子酸诱导电流的逆转电位比-80 mV更负，表明PCa/PCs值< 0.18。5.红藻氨酸诱导的电流反应分为两种类型。在I型反应中，在无Na+、10 mM-Ca ~（2+）溶液中，红藻氨酸诱导的电流的反转电位比-80 mV更负，表明这种类型的红藻氨酸通道的Ca ~（2+）渗透性与使君子酸通道一样低。在I型反应的神经元中，对照溶液中红藻氨酸反应的电流-电压曲线有向外整流的趋势。6.在II型反应中，红藻氨酸盐在无Na+、10 mM-Ca 2+溶液中在-60 mV下引起显著的内向电流。反转电位为-23.3 ±-。5.6 mV（n = 17），表明渗透率比PCa/PC = 2.3。在显示II型反应的神经元中，在对照溶液中红藻氨酸盐反应的电流-电压图中观察到显著的向内整流。7. II型红藻氨酸盐通道在二价阳离子之间显示出相对较差的选择性。渗透性顺序为Ba ~（2+）（1.3）> Ca ~（2+）（1.0）> Sr ~（2+）（0.9）> Mg ~（2+）（0.8）> Mn ~（2+）（0.7）。
1. N-methyl-D-aspartate (NMDA)-, quisqualate- and kainate-induced currents were recorded in cultured rat hippocampal neurones using the whole-cell voltage-clamp technique. To isolate the inward currents carried by Ca2+ and other divalent cations (Sr2+, Ba2+, Mn2+ and Mg2+), both Na+ and K+ in the control external solution were replaced with the impermeant cation N-methylglucamine (NMG). 2. Replacement of Na+, K+ and Ca2+ with NMG abolished NMDA-, quisqualate- and kinate-induced inward currents. In Na+-, K+-free (abbreviated simply as Na+-free) solution containing 10 mM-Ca2+ NMDA caused prominent inward currents at -60 mV. In this solution with the internal solution containing 165 mM-Cs+, the reversal potential of the NMDA-induced current was -5.0 .+-. 0.7 mV (n = 36), indicating a value of PCa/PCs = 6.2 for the ratio of the permeability coefficients of Ca2+ and Cs+ according to the constant-field equation. 3. NMDA elicited inward current responses at -60 mV in Na+-, Ca2+-free solution containing 10 mM-Sr2+, Ba2+, or Mn2+, but not in a Na+-free, 10 mM-Mg2+ solution. On the basis of reversal potential measurements, the permeability sequence of NMDA receptor channels among the divalent cations was determined to be Ba2+ (1.2) > Ca2+ (1.0) > Sr2+ (0.8) > Mn2+ (0.3) .mchgt. Mg2+ (< 0.02). 4. The reversal potential of the quisqualate-induced current was more negative than -80 mV in the Na+-free, 10 mM-Ca2+ solution, indicating a value of PCa/PCs < 0.18. 5. Kainate-induced current responses were classified into two types. In the type I response the reversal potential of the kainate-induced current was more negative than -80 mV in Na+-free, 10 mM-Ca2+ solution, indicating that the Ca2+ permeability of this type of kainate channel is as low as that of the quisqualate channel. In the neurones which showed a type I response, there was a tendency of outward rectification in the current-voltage plots of the kainate response in control solution. 6. In the type II response kainate caused prominent inward currents at -60 mV in Na+-free, 10 mM-Ca2+ solution. The reversal potential was -23.3 .+-. 5.6 mV (n = 17), indicating a permeability ratio PCa/PCs = 2.3. In the neurones which showed a type II response, a remarkable inward rectification was observed in the current-voltage plots of the kainate response in control solution. 7. Type II kainate channels showed relatively poor selectivity among divalent cations. The permeability sequence was Ba2+ (1.3) > Ca2+ (1.0) > Sr2+ (0.9) > Mg2+ (0.8) > Mn2+ (0.7).