Belgum J H, Dvorak D R, McReynolds J S
J Physiol. 1984 Sep;354:273-86. doi: 10.1113/jphysiol.1984.sp015375.
Transient and sustained inhibitory synaptic inputs to on-centre, off-centre, and on-off ganglion cells in the mudpuppy retina were studied using intracellular recording in the superfused eye-cup preparation. When chemical transmission was blocked with 4 mM-Co2+, application of either glycine or gamma-aminobutyric acid (GABA) caused a hyperpolarization and conductance increase in all ganglion cells. For both amino acids, the responses were dose dependent in the range 0.05-10 mM, with a half-maximal response at about 0.7 mM. Glycine and GABA sensitivities were very similar in all three types of ganglion cells. The response to applied glycine was selectively antagonized by 10(-5) M-strychnine and the response to applied GABA was selectively antagonized by 10(-5) M-picrotoxin. In all ganglion cells, 10(-5) M-strychnine eliminated the transient inhibitory events which occur at the onset and termination of a light stimulus. The block of transient inhibition was associated with a relative depolarization of membrane potential and decrease in conductance at these times. Strychnine had no effect on membrane potential or conductance in darkness or during sustained inhibitory responses to light. Picrotoxin (10(-5) M) did not block transient inhibitory events in any ganglion cells, but did affect other components of their responses. The results suggest that in all three classes of ganglion cells transient inhibition, but not sustained inhibition, may be mediated by glycine or a closely related substance.
在泥螈视网膜中，使用灌注眼杯制备中的细胞内记录法，研究了对中心开、中心关和开 - 关神经节细胞的瞬态和持续抑制性突触输入。当用4 mM - Co²⁺阻断化学传递时，施加甘氨酸或γ - 氨基丁酸（GABA）会导致所有神经节细胞超极化并电导增加。对于这两种氨基酸，在0.05 - 10 mM范围内反应呈剂量依赖性，在约0.7 mM时达到半数最大反应。在所有三种类型的神经节细胞中，甘氨酸和GABA的敏感性非常相似。对施加甘氨酸的反应被10⁻⁵ M的士的宁选择性拮抗，对施加GABA的反应被10⁻⁵ M的印防己毒素选择性拮抗。在所有神经节细胞中，10⁻⁵ M的士的宁消除了在光刺激开始和结束时出现的瞬态抑制事件。瞬态抑制的阻断与这些时刻膜电位的相对去极化和电导降低有关。士的宁在黑暗中或对光的持续抑制反应期间对膜电位或电导没有影响。印防己毒素（10⁻⁵ M）在任何神经节细胞中都不阻断瞬态抑制事件，但确实影响它们反应的其他成分。结果表明，在所有三类神经节细胞中，瞬态抑制而非持续抑制可能由甘氨酸或密切相关的物质介导。
