LIGAND-GATED CURRENTS OF ALPHA-GANGLION-CELLS AND BETA-GANGLION-CELLS IN THE CAT RETINAL SLICE
LIGAND-GATED CURRENTS OF ALPHA-GANGLION-CELLS AND BETA-GANGLION-CELLS IN THE CAT RETINAL SLICE
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DOI：
10.1152/jn.1994.72.3.1260
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发表时间：
1994-09-01
影响因子：
2.5
通讯作者：
FAIN, GL
中科院分区：
文献类型：
--
作者：
COHEN, ED;ZHOU, ZJ;FAIN, GL
1.我们使用膜片钳技术的全细胞记录变化，研究了猫视网膜切片制剂中ON-和OFF-α和β神经节细胞的配体门控电流的受体药理学。在 N-2-羟乙基哌嗪-N'-2-乙磺酸 (HEPES) 缓冲液中切割猫视网膜切片，并在碳酸氢盐缓冲溶液中孵育。在 HEPES 缓冲林格溶液中将神经节细胞电压钳位在 -70 mV。移液管溶液中含有低浓度的Cl-，以区分混合阳离子和Cl-介导的电导，并加入荧光黄（0.5%）用于鉴定细胞类型。2．在含有 1.2 mM Mg2+ 的林格溶液中，对兴奋性氨基酸激动剂 (EAA) N-甲基-D-天冬氨酸 (NMDA) (200 μM) 的反应电流-电压 (IV) 曲线显示出 J 形函数。在含有 200 μM Cd2+ 以阻断突触传递的不含 Mg2+ 的林格溶液中，NMDA (200 μM) 在 -70 mV 下引发了 5-8 倍大的内向电流。在这两种情况下，NMDA 感应电流的 I-V 曲线在 0 mV 附近反转。这些结果表明，α 和 β 神经节细胞的树突上直接存在 NMDA EAA 受体。对NMDA 的反应被+/-2-氨基-7-膦酰庚酸(AP7) (200 mu M)阻断。3。在含有200-1,000μM Cd2+以阻断突触传递的林格溶液中，ON-和OFF-α和β细胞均对红藻氨酸（10-50μM）、α-氨基-3-羟基-5-甲基异恶唑-4-丙酸（AMPA）（20-70μM）和使君子酸（0.1-30μM）产生内向电流反应， 在 0 mV 附近反转。这些反应被喹喔啉 EAA 拮抗剂 6-氰基-7-硝基喹喔啉-2,3-二酮 (CNQX) (10 μM) 阻断。代谢型激动剂1-氨基环戊烷-1,3-二甲酸(ACPD) (25μM)和L-2-氨基-4-膦酰丁酸(L-APB)(50μM)在Cd2+存在下对所有测试的细胞几乎没有或没有引起反应。4．在 Cd2+ 存在的情况下，α 和 β 细胞对 γ-氨基丁酸 (GABA) (200 μM) 和甘氨酸 (200 μM) 作出反应，内向电流在 -35 mV 附近反转，计算出的氯离子平衡电位 E(cl)。对 GABA 和甘氨酸的反应均具有强烈的脱敏作用。 (+)荷包牡丹碱甲基氯化物 (20 μM) 平均阻断 200 μM GABA 对所有神经节细胞类型引起的内向电流的 90%。巴氯芬 (10-100 μM) 对静息电流或电压门控 Ca2+ 电流没有影响。士的宁 (1 μM) 平均阻断甘氨酸诱发电流 94%.5。我们得出结论，ON-和OFF-α和β细胞上存在的兴奋性和抑制性离子型氨基酸受体非常相似。这表明在这些细胞的反应特性中观察到的一些差异可能是由于它们的突触前输入的不同特性或它们的电压门控通道的差异造成的。
1. We studied the receptor pharmacology of the ligand-gated currents of ON- and OFF- alpha and beta ganglion cells in a cat retinal slice preparation using the whole cell recording variation of the patch-clamp technique. Cat retinal slices were cut in N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) buffer and incubated in a bicarbonate-buffered solution. Ganglion cells were voltage clamped at -70 mV in HEPES-buffered Ringer solution. The pipette solution contained a low concentration of Cl- to distinguish mixed cationic from Cl--mediated conductances, and Lucifer yellow (0.5%) was included for identification of the cell type.2. In Ringer solution containing 1.2 mM Mg2+, current-voltage (I- V) curves of responses to the excitatory amino acid agonist (EAA) N-methyl-D-aspartate (NMDA) (200 mu M) revealed a J-shaped function. In Mg2+-free Ringer solution containing 200 mu M Cd2+ to block synaptic transmission, NMDA (200 mu M) elicited an inward current 5-8 times larger at -70 mV. In both conditions I-V curves of the NMDA-induced currents reversed near 0 mV. These results suggest that there are NMDA EAA receptors present directly on the dendrites of alpha and beta ganglion cells. Responses to NMDA were blocked by +/-2-amino-7-phosphonoheptanoic acid (AP7) (200 mu M).3. In Ringer solution containing 200-1,000 mu M Cd2+ to block synaptic transmission, both ON- and OFF- alpha and beta cells responded to kainic acid (10-50 mu M), alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA) (20-70 mu M), and quisqualic acid (0.1-30 mu M) with inward currents that reversed near 0 mV. These responses were blocked by the quinoxaline EAA antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) (10 mu M). The metabotropic agonists 1-aminocyclopentane-1,3-dicarboxylic acid (ACPD) (25 mu M) and L-2-amino-4-phosphonobutyric acid (L-APB) (50 mu M) in the presence of Cd2+ evoked little or no response for all cells tested.4. In the presence of Cd2+, alpha and beta cells responded to gamma-aminobutyric acid (GABA) (200 mu M) and glycine (200 mu M) with inward currents that reversed near -35 mV, the calculated chloride equilibrium potential E(cl). Responses to GABA and glycine were both strongly desensitizing. (+)Bicuculline methyl chloride (20 mu M) blocked an average of 90% of the inward current evoked by 200 mu M GABA on all ganglion cell types. Baclofen (10-100 mu M) had no effect on resting currents or on voltage-gated Ca2+ currents. Strychnine (1 mu M) blocked glycine-evoked currents by an average of 94%.5. We conclude that the excitatory and inhibitory ionotropic amino acid receptors present on ON- and OFF- alpha and beta cells are very similar. This suggests that some of the differences observed in the response properties of these cells may be due to different properties of their presynaptic inputs or differences in their voltage-gated channels.